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HOW TO DESIGN AN EXPLORATION SURFACE SOIL
GAS GEOCHEMICAL SURVEY: ILLUSTRATED BY
APPLICATION EXAMPLES FROM THE HUGOTON
EMBAYMENT OF SOUTHEAST COLORADO AND
SOUTHWEST KANSAS
Rufus J. LeBlanc, Jr., and Victor T. Jones, III
Exploration Technologies, Inc.
AAPG Annual Convention, April 18-21, 2004
Dallas, Texas
Aerial Photograph of a modern-day incised valley in the Lower Jurassic Navajo Sandstone of east-central Utah. This is an excellent analog for the Morrow incised valley-fill sandstones of the Stateline Trend of eastern Colorado and western Kansas.
Image: Cover photograph of September 2002 AAPG Bulletin
HOW TO DESIGN AN EXPLORATION SURFACE SOIL GAS GEOCHEMICAL
SURVEY: ILLUSTRATED BY APPLICATION EXAMPLES FROM THE HUGOTON
EMBAYMENT OF SOUTHEAST COLORADO AND SOUTHWEST KANSAS
Rufus J. LeBlanc, Jr., and Victor T. Jones, III
ABSTRACT
Three regional surface geochemical soil gas surveys covering areas of 150, 53, and 209 square miles
were conducted in the Hugoton Embayment of southeast Colorado and southwest Kansas. The three
surveys exhibit different sampling densities and comprise both reconnaissance and detailed grids. The
surveys were conducted over the prolific Pennsylvanian Morrow Stateline Trend and the Permian Chase
Carbonate Gas Trend.
The stratigraphic entrapment of oil and gas in these two plays, relatively shallow depth, and highly
variable porosity and permeability of the reservoirs are factors which favor the application of surface soil
gas surveys as an important exploration method to reduce risk in exploration, exploitation, or development
efforts in these two plays. Examples of actual reconnaissance and detailed surface soil gas surveys in
this petroleum province are discussed.
The surveys were conducted from 1987 to 1992 before there was the widespread development drilling as
witnessed today. Both the benefits and limitations of a reconnaissance survey over the Stateline Trend
from Frontera to Second Wind Fields are discussed. A detailed survey in the Moore-Johnson Field area
illustrates the benefits of surface geochemistry in risk reduction in this stratigraphicly complex area. An
example of a detailed soil gas survey over Byerly Field in Greeley County, Kansas is presented which
depicts the complex porosity and permeability variations in the Chase Carbonate.
from a properly designed survey. The factors listed in Table 1 are critical for the successful design,
employment, and interpretation of a soil gas survey Another reason for past failures may have been in
the sample technique used in the collection of the soil gas samples (Jones, 2004, in review).
The considerations for sample spacing presented in this paper are not only the result of the authors work
with exploration surveys in the area over a 16-year period, but also the result of having concurrently
employed surface soil gas geochemistry in environmental assessments of petroleum contaminated sites.
Reservoir heterogenities in shallow sedimentary rock units of shallow vadose zones and aquifers are
very readily apparent from the surface microseep anomalies observed from the extremely high-density
soil gas grids used in these applications. An example of such an application is provided in Agostino,
LeBlanc, and Jones (2002).
Exploration soil gas surveys may be designed so that they are very inexpensive and regional in nature,
with very few soil gas samples, or they may be designed so that they are more detailed, with dense spacing
of soil gas sample sites. As will be demonstrated with application examples, there is a critical balance in
the design of surface geochemical surveys that must be met if useful results are to be attained.
Measuring natural gas microseepage, like any scientific analytical method dealing with nature is not
perfect. Interpretations of soil gas geochemistry should always be used in conjunction with subsurface
geology and geophysics. Another important concept to remember is that there is no direct relationship
between the magnitude of a surface microseep and the resultant volumetric hydrocarbon production
or economics of a corresponding well or field. Soil gas microseepage, measured at the surface, is the
result of light hydrocarbon gases in a reservoir being pressure-driven upward to the surface along natural
fractures in the subsurface.
The paper is a retrospective analysis of soil gas surveys conducted in this complex area in light of new
geologic knowledge of the area that has been revealed in the past decade.
A general rule-of-thumb concerning soil gas surveys is that more soil gas sites per unit area are required
in stratigraphic fairways than in structural fairways. However, some caution should be taken in this
generalization, as there are few structural hydrocarbon accumulations that do not also have some
stratigraphic variations in the reservoir.
INTRODUCTION
Three regional surface geochemical soil gas surveys covering areas of 150, 53, and 209 square miles
were conducted in the Hugoton Embayment of southeast Colorado and southwest Kansas. The
surveys were conducted from 1987 to 1992 before there was the widespread development drilling as
witnessed today. This paper describes various configurations for soil gas surveys that may be designed
and discusses the type of exploration information that can be expected from each survey design from
reconnaissance to detailed soil gas surveys. Examples will be drawn from the actual soil gas surveys in
these areas.
The hypothesis that natural soil gas microseeps detected at the surface from underlying hydrocarbon
deposits could continue to be useful as an exploration method is a natural extension of the mapping of
macroseeps, which led to the very early discovery of many oil and gas fields in petroleum basins all over
the world (Link, 1952). A history of the development of surface soil gas geochemistry may be found in
Jones et al. (2000).
Twenty years ago, in 1983, Jones and Drozd published a paper in the AAPG, which improved our
understanding of two important basic concepts of surface soil gas geochemistry – magnitude and
composition as relating to subsurface reservoirs, significantly improving the viability of surface
geochemical prospecting as a viable exploration method.
One of the primary reasons for past failures in the application of surface geochemical surveys is a lack of
a proper design of the sampling grid. Few explorationists have adequate knowledge on how to design a
surface soil gas survey, and as a result do not accrue nor appreciate the benefits that can be expected
How to Design an Exploration Surface Soil Gas Geochemical Survey
The Hugoton Embayment provides an excellent petroleum basin with which to illustrate these methods
for the following reasons: (1) simple tectonics with little faulting, (2) the gas microseepage is vertical, (3)
shallow to intermediate depth productive horizons, (4) wide range of types of soil gas surveys, (5) the
area contains both oil and gas trends, each having different unit spacing, (6) the resultant oil and gas
production in these trends is in the “giant field” category, (7) the actual concentrations of the free soil gas
microseepage in these areas has very low magnitudes so that the background concentrations approach
zero, and (8) the oil and gas accumulations are predominantly stratigraphic, providing an additional
impetus to use geochemical data in this type of high-risk exploration play.
Page 2
BASICS OF SURFACE SOIL GAS SURVEYS
In its simplest mode, soil gas samples can be collected from a depth of four feet by means of a hand-held
collection probe into a small volume (125 ml) glass sample bottle. These simple collection techniques do
not require elaborate logistics, in addition to providing low collection costs, enabling rapid collection, and
being generally unobtrusive to the environment.
The general objective of soil gas surveys is to collect and measure microscopic concentrations
(microseeps) of methane, ethane, propane, and butane found in the void spaces of near-surface soils that
overlie subsurface petroleum reservoirs. These gases are the lightest and most volatile constituents in
crude oil, condensate, and natural gas reservoirs and because of this characteristic are the most important
components to quantify and map.
.
A most important requirement for mapping these natural seeps is that the laboratory analytical instruments
must have the capability to detect very low concentrations, in the parts per billion (ppb) range, for methane,
ethane, propane, and butanes.
APPLICATIONS FOR SURFACE GEOCHEMICAL SURVEYS
A. Surface Geochemistry as a Reconnaissance
Exploration Tool
CONCEPT
BASIC
GEOLOGY
(1, 2, 3) SURFACE
GEOLOGY
LEASING
GEOPHYSICS
INTEREST AREA
GEOLOGY
Geochemistry can be applied to LARGE areas - such as basins,
concessions, and plays. It is applied in "series" fashion with the
more costly tools used later.
Objectives:
1. To identify interest areas, based on gross hydrocarbon character, at
a low cost per square mile.
2. To select most valuable concessions; focus exploration in frontier
areas.
3. To differentiate oil-prone from gas-prone or thermally-mature versus
immature areas.
B. Surface Geochemistry as a Detail Exploration
Tool
Geochemistry can be applied to known interest areas previously
identified by other methods (geophysics, leasing, and geochemistry).
It is usually applied in "series/or parallel" fashion with other tools.
(4) SURFACE GEOPHYSICS
GEOCHEMISTRY
PROSPECTS
IDENTIFIED
FURTHER EVALUATION
OR DRILLING
Objectives:
4. To identify drilling prospects; usually used in conjunction with
geophysics.
LEASING
GEOLOGY, GEOPHYSICS
PROSPECTS
ABCD
(5, 6) SURFACE
GEOCHEMISTRY
5. To rank drilling prospects on the basis of their most favorable
geochemical characteristics.
6. To assist a drilling partner to decide to participate/not participate
in one or more of a series of wells.
MOST FAVORABLE
PROSPECTS ARE DRILLED
WILDCAT
DISCOVERY
(7) SURFACE
GEOCHEMISTRY
7. To define the areal extent of an oil accumulation to assist orderly
field development.
FIELD DEVELOPMENT
Boleneus, David, 1994. Guidelines, etc. Oil & Gas Journal, June 6, pp 59-64
Figure 1
How to Design an Exploration Surface Soil Gas Geochemical Survey
Soil gas surveys may be used
at any stage of exploration in a
petroleum basin – whether in the
frontier stage of an unexplored
basin or in the development
stage of a mature basin.
An excellent summary that
illustrates the variety of different
stages in the application of soil
gas geochemistry has been
discussed by Boleneus (Figure
1). If employed very early in
basin exploration, soil gas
surveys can provide justification
for purchasing “trend acreage”,
or if geophysical data is lacking,
can be used as further criteria
for strengthening a subsurface
lead.
Soil gas surveys may be
classified as reconnaissance,
detailed, regional, or local. The
particular survey conducted
must be tailored to the
exploration objectives.
Regional surface geochemical
soil gas surveys may be
conducted at any stage in basin
exploration – frontier, semimature, or mature. Local soil
gas surveys have been employed in the explotation or development stages of a play or field. Soil gas
surveys have also been documented to be beneficial during the secondary recovery efforts in a particular
field much like the current employment of 3-D and 4-D seismic surveys for these purposes.
Soil gas sample density per unit area determines whether a regional soil gas survey is a reconnaissance
survey or a detailed survey. In a detailed survey the sample density should be commensurate with the
expected prospect areal extent or well spacing of a particular play. Special high-density soil gas spacing
has been used in surveys conducted for the development drilling of fields and later in secondary recovery
efforts.
Reconnaissance surveys are typically employed in the frontier or semi-mature exploration stages of a
concession or basin. There is less justification for a reconnaissance survey in a mature basin. Because
reconnaissance soil gas surveys are the least costly exploration technique, they should be applied in
series fashion with the more costly exploration techniques (gravity, magnetics, reconnaissance 2-D
seismic) following later. However, exceptions do occur. A reconnaissance survey conducted across the
Powder River basin in 1976 resulted in the discovery of the Hartzog Draw field (second largest field in
this mature basin).
Detailed soil gas surveys are used in later exploration stages to acquire additional exploration information
in areas of interest delineated by a reconnaissance survey. Detailed soil gas surveys are typically
applied in a parallel fashion with other exploration methods (wildcat wells, detailed 2-D seismic grids, 3-D
seismic).
An additional benefit of soil gas surveys is the capability to differentiate (using compositional ratios)
between oil-prone or gas-prone fairways in a particular concession or basin or whether certain areas
are thermally over-mature or immature. The concept and application of compositional ratios has been
discussed in detail by Jones and Drozd (1983) and Jones et al. (2000).
Interpretation of soil gas data involves presenting the geochemical dataset within the most current and
detailed geological and geophysical framework available. The magnitudes of the four light gases may be
presented many different ways for interpretational presentations:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
Presenting the microseep magnitudes in a profile graphic.
Presenting the microseep profile in conjunction with a subsurface geologic cross-section
or a seismic line.
Presenting a group of microseep profiles as a fence-diagram graphic.
Presenting the microseep magnitudes in the form of an interpretative contour map.
Presenting the microseep magnitudes in the form of a dot map where the diameter of the
dots (at each soil gas site) is directly related to the light gas magnitudes. This presentation
gives an unbiased interpretation as opposed to a contour map.
If compositional ratios of the microseeps are used, then the predicted hydrocarbon (oil,
condensate, gas) is indicated by color-coding within the magnitude dot maps mentioned
above.
Presenting the microseep magnitudes in the form of a Pixler Plot.
Anomalous concentrations of methane, ethane, propane, and butanes detected at the surface are always
real seeps, since active flux is necessary to overcome near surface interfering effects.
Page 3
A. LOCATION MAP HUGOTON EMBAYMENT
ge
brid
CamArch
ns
Tra
ch
l Ar
Colorado
nta
tine
n
o
c
Salina
Basin
Nebraska
lK
ra
nt
Ce
Kansas
s
sa
an
GENERAL GEOLOGY OF THE HUGOTON EMBAYMENT
The Hugoton Embayment of southwest Kansas and southeast Colorado, shown in Figure
2A, is a wide, southward-plunging Paleozoic syncline of about 12,000 square miles that
is bounded on the west, north, and east by uplifted areas. The Hugoton Embayment is
the shallower, northward extension of the deeper Anadarko Basin of western Oklahoma
and the Texas Panhandle. The Hugoton Embayment is bounded on the west by the Las
Animas Arch, on the north by the Transcontinental Arch, and on the east by the Central
Kansas Uplift. Sedimentary rocks thicken towards the center of the basin and southward
to about 9000 feet near the Kansas-Oklahoma border.
sA
rch
t
lif
Up
DENVER
BASIN
An
ima
Hugoton
Up
li
500
Embayment
ft
Oklahoma
an
de
Ar
Cim
Arcarron
h
ch
Ap
ish
ap
a
Las
0
50
0
Gr
Texas
1000
25
0
50
0
0
Si
er
ra
500
Dalhart Basin
Ama
New
Mexico
200
0
rillo
0
300
Upli
ft
0
EXPLANATION
HIGH-ANGLE FAULT
HACHURES ON DOWNTHROWN SIDE
PRECAMBRIAN ROCKS EXPOSED
0
25
50
75
100 mi
0
40
80
120
160 km
Anadarko
Basin
40
00
The USGS has recognized 25 different petroleum plays in the Hugoton Embayment and
Anadarko Basin (USGS, 1995). Every Paleozoic system that is represented in both these
basins has produced some hydrocarbons. The province overall produces primarily gas.
According to recent production data, compiled by the USGS, the province has produced
more than 2.3 BBO and 65.5 TCFG since the early 1900’s. Stratigraphic trapping
mechanisms are the most common, combination types less common, and structural types
the least common. Pennsylvanian and Permian reservoirs have produced the largest
volumes of hydrocarbons to date.
The two petroleum plays discussed in this paper are the Pennsylvanian Morrow Sand Oil
Trend and the Permian Chase Carbonate Gas Trend illustrated in Figures 2B and 2C,
respectively.
Wichita Mtn.
Uplift
Morrow Isopach
Contours in ft
GENERAL GEOLOGY OF HUGOTON EMBAYMENT
POSITIVE
AREAS
BASIN
AREA
AREA OF
OIL TREND
AREA OF
GAS TREND
Figure 2
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 4
Pennsylvanian Morrow Sand Oil Trend
MARINE SHALE
A
ge
rid
MISSISSIPPIAN
LIMESTONE
SUBCROP
rch
Abandoned
Highstand
Position
al
ent
tin
on
nsc rch
a
r
A
T
mb
Cheyenne Co.
KANSAS
Lookout
Sherman Co.
Wallace Co.
Ca
COLORADO
B. PENNSYLVANIAN MORROW SAND OIL TREND
Nebraska
Kansas
Ancestral Front Range
s
sa
an
ND
MORROW
SAND
CHANNELS
t
lif
Up
TRE
INE
TEL
Frontera
lK
ra
nt
STA
Arapahoe
Ce
Harker Ranch
Colorado
Mount Sunflower
Sierra Grande
Uplift
Oklahoma
Lowstand Shorelines
Texas
Greeley Co.
Stockholm SW
Abandoned
Highstand
Position
Second Wind
Sidney
Am
aril
lo U
t
Wic
h
100 mi
mi
km
Up
lift
MORROW PALEOGRAPHY
Moore-Johnson
0
ita
160 km
Jace
Regional dip at the top of the Morrow is to the east-southeast. Drill depths to the Morrow
reservoirs ranges from 5000 to 5500 feet. Average cumulative production from wells in this
trend has ranged from 40,000 to 155,000 BO per well.
A comprehensive compilation of 23 papers on the fields within the Morrow oil trend over the
Las Animas Arch and Hugoton Embayment was published by the RMAG (Sonnenberg et
al., 1990). Further details of the area may be found in Bowen, 2001. Recently, an excellent
summary of the Morrow sequence stratigraphic framework and the relational aspects to
reservoir geometry and geology and reservoir performance was presented by Bowen and
Weimer (2003).
plif
Kiowa Co.
0
INCISED MORROW VALLEYS
10
10
DISTRIBUTION OF OIL FIELDS
IN MORROW TREND
Permian Chase and Council Grove Carbonate Gas Trend
C. PERMIAN CHASE CARBONATE TREND
Wallace
Gove
Logan
A
West
BR
AD
SHA
W
BYERLY
Greeley
Wichita
Scott
A’
East
Lane
Red Shale
and Siltstone
Kearney
OM
PAN
Gray
TON
Grant
Haskell
SEWARD
Sumnex
Cou
ncil
Chase
Gro
ve
Gas-Water Contact
GR
A
EEN
W
OO
D
HU
GO
Stanton
Regional dip of the Permian Carbonates is to the east-southeast. Average drill depths of the
gas reservoir at Byerly Field, in the extreme north of the Hugoton Embayment, range from
about 2750 to 2900 feet. Cumulative gas production from individual wells in Byerly Field has
ranged from 30 MMCFG to 3,572 MMCFG.
STEVENS
Wabaunsee
Shawnee
The Permian Carbonate Gas Trend (Chase and Council Grove Groups) in the Hugoton
Embayment is the most prolific and important hydrocarbon play in this petroleum province.
The major gas fields of this area – Hugoton, Panoma, Greenwood, Bradshaw, and Byerly
have produced a total cumulative of 27 TCFG. The natural gas accumulations in these fields
are due to stratigraphic entrapment caused by a facies change in the Permian Chase and
Council Grove Carbonate reservoirs where they grade from limestones and dolomites in the
east to nonmarine red beds in the west (Figure 2C). The upper seal for the gas reservoirs are
provided by anhydrites and shales of the overlying Sumner Group.
MORTON
Admire
Finney
A
Hamilton
Pennsylvanian Morrow fluvial sand channels developed both within and along the margins of
the Morrow paleobasin during major regressive events in Early Pennsylvanian time (Figure
2B). There are five recognized regressive-transgressive cycles within the Upper Morrow
Formation (Bowen and Weimer, 2003). River valleys were incised into either underlying
Lower Morrow or Upper Mississippian limestones and were subsequently progressively filled
with fluvial sands, estuarine sands, and finally, marine muds. The distribution of Morrow
Sand channels within the incised valleys is commonly very complex, sometimes involving
cross-cutting relationships. Later channel stages are frequently incised into earlier ones. The
portion of the Morrow Trend mentioned in this paper is commonly referred to as the Stateline
Trend and the complex of fields extends for about 60 miles in a north-south direction along the
Colorado and Kansas state boundary (Figure 2B). The collection of fields in this complex will
have an ultimate recovery of more than 100 MMBO and 500 BCFG.
A’
Morton
Stevens
Seward
STRATIGRAPHIC ENTRAPMENT IN CHASE CARBONATE
Meade
DISTRIBUTION OF GAS FIELDS
IN CHASE TREND
Figure 2
How to Design an Exploration Surface Soil Gas Geochemical Survey
The stratigraphic entrapment of oil and gas in these two plays, relatively shallow depth, and
highly variable porosity and permeability of the reservoirs are factors which favor the application
of surface soil gas surveys as an important exploration method to reduce risk in exploration,
exploitation, or development efforts in these two plays. Examples of actual reconnaissance
and detailed surface soil gas surveys in this petroleum province are discussed below.
Additional information on the Chase Carbonate may be obtained from the Kansas Geological
Survey website and Bebout et al. (1993).
Page 5
B. 1987 Oil and Gas Field Development and New Discoveries in Stockholm Area
A. 1979 Oil and Gas Fields in Stockholm Area
FUNK
MISSISSIPPI OIL
28
27
19
26
25
30
20
19
24
COLORADO
24
21
22
23
24
19
26
25
30
35
36
31
ARAPAHOE
MORROW GAS
27
28
29
30
25
28
27
19
20
21
22
25
30
29
28
27
36
31
32
33
34
24
These four fields were discovered as a result of various exploration plays on lowrelief structures.
KANSAS
23
ARAPAHOE
MORROW GAS
COLORADO
22
KANSAS
21
FUNK
MISSISSIPPI OIL
22
21
By the end of 1986, SW Stockholm Field had been developed to the extent shown
on Figure 3B. The field contained 53 wells and extended for four miles along the
arcuate axis of the field. A history of field development was discussed by Shumard
(1991). During 1987 there were three significant developments in the area: (1)
TXO completed a one-half mile field-extension in March with the Wallace # 1-R. (2)
In April 1987, Medallion drilled a Morrow oil new field discovery with the Arapahoe
# 27-1 eight miles to the north of SW Stockholm Field. (3) In July 1987, Mull Drilling
established a Morrow oil new field discovery with the Stateline Ranch # 1 well four
miles north of SW Stockholm Field. These three wells, along with the wells of SW
Stockholm Field had, in general terms, defined a Morrow sand oil fairway for a
distance of 10 miles in a north-south direction (Figure 3B). A decision was made
to conduct a reconnaissance surface soil gas survey in the area using 11 samples
per section. A profile line of samples taken from this low-density grid will be used
to illustrate the differences between profile versus surveys conducted on a grid
pattern.
36
36
31
34
33
32
31
33
34
K225
ENCAPMENT
MISSISSIPPI OIL
4
3
2
1
6
9
10
11
12
7
1
6
12
7
4
5
K227
K229
K228
10
K232
K231
K230
K233
K234
1
6
5
4
3
12
7
8
9
10
Mull Drlg.
Stateline Ranch #1 13
18
17
16
15
19
20
21
22
4
3
2
1
6
9
10
11
12
7
W STOCKHOLM
MORROW GAS
18
21
22
23
24
19
27
26
25
33
2
36
14
13
18
21
22
23
24
19
27
26
25
24
15S42W
34
33
34
3
5
7
12
15
15S42W
15S41W
6
16
28
31
1
11
27
33
32
31
2
10
28
29
30
25
35
22
30
36
34
3
15S43W
15S42W
28
21
20
19
24
15
1
6
5
4
12
7
8
9
18
17
16
8
2
11
10
C.R. Assoc.
Evans #1
11
35
30
29
28
27
36
31
32
33
34
Profile Line
SW
STOCKHOLM
31
6
7
12
TXO
Wallace # 1-R
25
30
36
1
15S42W
13
W STOCKHOLM
MORROW GAS
16
15S41W
14
15S43W
15
17
18
13
16
K235
Soil Gas Profile
ENCAPMENT
MISSISSIPPI OIL
3
9
8
K226
14S43W
14S42W
35
14S43W
14S42W
34
14S42W
14S41W
33
14S42W
14S41W
Medallion
Arapahoe #27-1
5
2
1
6
5
4
11
12
7
8
9
14
13
18
17
16
8
Eleven soil gas sites collected in a single east-west profile, 3.5 miles long, along
a highway that was north of the well established Morrow oil production at SW
Stockholm Field and about half way between the two new field discoveries is shown
in Figure 3B. Typically, such a soil gas profile would have been placed along the
trace of a geophysical seismic line if one was available. The ethane magnitudes
shown on this profile indicate a possibility that the Morrow oil production fairway
also extended between the two Morrow oil new field discoveries.
TXO
Evans #1
K225
K226
K227
K229
K228
36
31
K232
K231
K230
K233
K234
K235
Soil Gas Anomaly
2
ENCAPMENT
Field
6
1
6
1
1 Mile
SOIL GAS PROFILE ETHANE MAGNITUDE
Ethane Magnitude (ppb)
60
50
40
30
20
10
K225
K226
K227
K228
K229
K230
K231
K232
K233
17
16S42W
18
13
RECONNAISSANCE SOIL GAS SURVEYS
31
14S43W
14S42W
14S42W
14S41W
36
1 Mile
16S43W
16S42W
16S43W
16S41W
13
C. November 1987 Reconnaissance Soil Gas Profile
35
14
15
14
16S41W
17
16S42W
1 Mile
16S42W
18
13
14
15
K234
K235
Reconnaissance soil gas surveys typically are conducted over
a large area with wide spacing between soil gas sample sites.
The soil gas samples may either be collected along single
line profiles or in a regular grid pattern. Examples of surveys
conducted over oil fields in the Stateline Trend of the Morrow
oil fairway will be used to demonstrate these concepts.
In 1979, TXO drilled the discovery well for SW Stockholm
Field (and the Stateline Trend) at the location shown on Figure
3A. At this time, there were only four fields in the immediate
area (Figure 3A). There were two one-well abandoned
Mississippian oil Fields (Funk and Encampment Fields) and
two Morrow gas fields (Arapahoe and W Stockholm Fields).
On the soil gas profile (Figure 3C) the ethane concentrations range from nine to
forty parts per billion (ppb). Background concentrations of ethane occur at sites
225, 227, 228, and 235. The anomalous ethane magnitude at site 226 on the
profile appears to be the result of gas microseepage from the one-well abandoned
Encampment Oil Field (Mississippian). Anomalous ethane magnitudes at site
229 through site 234 (six sites) represent gas microseepage that appears to be
from the subsurface Morrow oil reservoir. The anomalous ethane concentrations
extend for a distance of 8800 feet (1.7 miles). This width is consistent with the
maximum width of SW Stockholm field.
At this stage, an exploration well could have been drilled within the anomalous
area, provided that the geochemical anomaly was supported by geology and/or
geophysics, or a reconnaissance soil gas survey could be conducted on a uniform
grid pattern in order to more rigidly define the suggested Morrow oil trend trend.
Based on this encouraging data, a reconnaissance soil gas survey conducted over
this area is discussed below.
Figure 3
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 6
B. Soil Gas Survey Conducted - November 1987
Ethane Magnitude Contour Map
COLORADO
26
25
28
29
30
25
30
K094
K093
K092
K124
K146
K147
27
K074
K096
23
K122
K121
K120
K145
K123
K095
22
K119
K118
K073
13
K148
K076
K126
K127
K098
K097
24
K125
25
24
K099
19
18
K080
K079
17
K129
K131
K130
20
K227
K229
K228
K197
K198
K221
K225
K224
K223
K222
K179
K226
K229
K228
K227
K204
36
31
K205
K232
K231
K230
K325
K326
27
26
25
30
34
35
36
31
3
2
1
6
10
11
12
7
15
14
13
18
22
23
24
19
27
26
25
30
36
31
K137
K159
K158
28
K187
16
24
19
20
21
25
30
29
28
36
31
32
33
1
6
5
4
12
7
8
9
13
18
17
16
24
19
20
21
25
30
29
28
36
31
32
33
Reconnaissance Soil Gas Survey on a Uniform Grid
K190
K189
K188
31
K238
K237
K236
K235
K234
K233
32
K211
K210
K209
K208
K207
K206
33
K241
K240
K239
K306
K305
11
K328
K355
K329
K307
12
K332
K331
K330
K356
21
K406
K357
14
K377
K378
12
K308
7
28
29
13
K383
K382
K381
K380
K411
K410
K409
K431
K511
SW
STOCKHOLM
K413
K437
K436
24
K513
K489
K488
K516
K515
K514
34
35
K517
36
5
2
5
6
7
K315
9
K389
K388
K589
11
K567
K344
K343
K569
25
K518
K765A
12
K415
K620
K621
K391 K391A
K367
16
K393
K392
K396
K395
K394
K418
K417
K416
K420
K419
21
20
19
K446
K470
K469
K468
K467
K466
K445
K444
K443
K442
K441
K440
K447
K448
K499
K500
K472
K471
28
29
30
K521
K520
K525
K524
K523
K522
33
32
31
36
34
K549
K548
K547
K546
K545
K544
35
K552
K551
K550
K574
K574A
K575
K595
K596
K597
K625
K626
K627
K578
K577
K576
2
K581
K580
1
6
5
2
1
6
5
11
12
7
8
14
13
18
17
5
6
1
K573
K572
K599
K598
K600
K602
K601
K603
K60
K604
K594
K593
7
8
K623
K622
K498
K497
K496
K495
K494
K493
K492
7
12
11
K630
K629
K628
8
K632
K631
8
7
12
11
K619
K390
K366
17
K542
5
K571
K570
K592
K591
K590
ETHANE
K618
K617
CONCENTRATIONS
K364
31
6
K568
K365
K363
18
2
8
7
12
K314
K342
K490
K541
K540
K539
K538
1
K566
K565
8
11
K537
K536
K535
K534
K533
K564
12
K341
K340
30
K487
K486
K485
K362
K414
K543
1
8
K339
K338
K337
K361
K439
K438
K465
K464
K463
25
K484
K483
K482
K512
K532
2
7
K313
K312
K311
K310
K336
K519
33
32
31
6
K293
19
K435
K434
K462
K461
26
K481
K480
1
K292
K386
K412
24
K433
K432
K460
27
13
K360
18
K385
K384
23
K430
K459
K458
31
36
4
K291
K334
K333
K359
K358
TXO
Wallace # 1-R
30
36
K290
K289
K263
K262
K261
5
K288
K287
K286
K309
K491
35
6
K285
K260
K259
K258
K257
K284
K387
K379
K408
K407
K429
K428
30
1
K283
K764A
20
15S42W
15S43W
15S42W
15S41W
K256
6
K282
K281
K280
K279
K304
K327
22
25
1
K335
K354
K353
19
25
K303
10
15
19
K255
K254
K253
K278
15S43W
24
26
11
19
17
15S42W
K302
K324
18
24
23
K277
K276
16
17
18
K252
2
K275
K301
K376
2
24
18
15S43W
3
15S42W
Mull Drlg.
Stateline Ranch #1 13
13
K251
K250
K274
9
8
7
12
W STOCKHOLM
MORROW GAS
34
23
13
K180
K203
K202
36
22
21
15S42W
K249
7
12
14
27
K178
K177
K201
4
5
6
1
6
1
11
22
K176
K235
K273
15
K175
K200
35
15S42W
2
10
K174
K199
34
14S43W
14S42W
14S43W
14S42W
K232
K231
K230
K234
K233
K173
K172
K171
33
32
31
18
K105
K136
K157
K186
K185
K184
K183
K182
13
Soil Gas Profile
ENCAPMENT
MISSISSIPPI OIL
3
36
31
15S41W
K226
K225
14S42W
14S41W
36
35
14S42W
14S41W
K170
34
K181
14
K085
29
30
25
K135
K156
K155
K154
K153
K152
30
Medallion
Arapahoe #27-1
15
K134
K133A
K132
16
K104
K103
K102
K133
K128
K084
K083
K082
K081
K101
19
K100
C. Stateline Complex Development
August 1990
K060
K059
K058
K057
K056
K078
K077
K151
K150
K149
26
K075
13
K055
18
15S41W
27
21
20
19
24
19
K072
K054
K053
KANSAS
24
K071
K070
K069
K052
14
COLORADO
23
ARAPAHOE
MORROW GAS
K068
K067
KANSAS
22
15
14S43W
14S42W
FUNK
MISSISSIPPI OIL
K051
K050
K049
K048
14S42W
14S41W
16
17
18
13
18
KANSAS
13
COLORADO
A. Stateline Complex Development
January 1987
14
15
K624
(ppb)
K657
K656
K677
K683
K682
K680
K679
14
13
K681
K701
K700
K702
K703
K685
17
18
1 Mile
K699
K684
K705
K704
18
13
14
K678
K706
K707
K708
17
16S42W
17
K676
16S43W
K675
K655
16S42W
K674
K654
K653
16S41W
18
K673
K672
K652
16S42W
K644
K643
13
K671
16S43W
17
18
K651
K650
K646
K645
16S41W
13
K649
K648
K647
K642
16S42W
14
16S42W
16S41W
17
16S43W
18
13
16S42W
14
> 30
25 - 30
1420 - 25
15 - 20
< 15
K641
K709
Figure 4
Lookout
20
21
22
23
24
27
26
25
30
29
28
34
35
36
31
32
33
19
15S42W
15S41W
Cheyenne County
Harker Ranch
MT. SUNFLOWER
FIELD
ATE
"ST
ianna
E
LIN
Arapahoe
Wallace Co.
Greeley Co.
Mount Sunflower
Arrowhead
Stockholm SW
Second Wind
Greeley County
16S42W
16S41W
"
ND
TRE
Frontera
4
3
2
1
6
5
9
10
11
12
7
8
16
15
14
13
18
17
24
19
20
Sidney
AREA OF
DETAIL MAP
Jace
Moore-Johnson
SIDNEY
FIELD
0
McClave
mi
0
km
10
21
22
23
10
1 Mile
28
27
26
25
30
29
Figure 5
How to Design an Exploration Surface Soil Gas Geochemical Survey
A reconnaissance soil gas survey was conducted in November 1987 over an area of 150
square miles as shown in Figure 4A. The soil gas sample grid used (11 sites per section or
square mile) was selected, both to make sample collection rapid by using the existing road
network, and to limit the number of sites over such a large area. Because the well spacing
of 80 acres per well had been established at SW Stockholm Field, the particular sample
density used for this survey requires defining this survey as a reconnaissance survey. The
area of the survey was also chosen to include other recent Morrow discoveries to the north
of SW Stockholm Field, so that the soil gas data could be calibrated to the oil production
with respect to magnitude and composition. A total of 798 soil gas sites were collected
over this 150 square mile area. The interpreted soil gas data over the productive trend is
illustrated by the ethane magnitude contour map shown in Figure 4B. It can be clearly
seen that as early as 1987 (and prior to), the soil gas survey had accurately defined the
general areal extent of the productive Morrow incised valley as would be confirmed by
development drilling three years later in 1990 (Figure 4C). It can also be discerned that,
at this sample density, that the soil gas data is inadequate for use in determining 80-acre
drilling sites. Thus, the selected density for this survey conducted in 1987 was at the
minimum threshold required to provide useful exploration information. This portion of the
Morrow Stateline Trend, to date, has produced a total of 34 MMBO from 299 development
wells. A retrospective analysis of this soil gas survey was previously discussed by
Dickinson et al. (1994)
A number of untested soil gas anomalies still exist in the remainder of the survey area
to the east of the Stateline Trend. These untested soil gas anomalies exhibit similar
magnitudes and areal extents as the anomalies mapped within the Stateline Trend.
Substantiation that these untested soil gas anomalies do indeed outline areas of additional
Morrow oil potential may be seen in the recent development of the Mount Sunflower and
Sidney Morrow oil fields in Wallace and Greeley Counties, Kansas. As shown in Figure
5, these two Morrow oil fields now contain a total of 40 oil wells and have produced a
total of 2.85 MMBO. Development drilling in these two new fields progressed from 1990
through 1999 and has been conducted by 13 different independent oil companies. The
significance of this new Morrow oil production is that, together, the two fields have defined
a new Morrow oil productive fairway that is about two miles wide and extends for seven
miles in a north-south direction (Figure 5).
The new fairway is four miles east of the older Stateline Trend Morrow oil production.
Although the productive area of these two fields is predominantly outside of the area of
the 1987 reconnaissance soil gas survey, there are soil gas anomalies that border the
current production at these two fields and suggest the possibility of even further extension
of this newly established production in the Morrow oil trend. This is an excellent example
of an area where a later detailed soil gas survey could be conducted and combined with
an earlier reconnaissance survey. A detailed soil gas survey in this area would greatly
enhance the explotation/development efforts in this new Morrow oil trend.
Other important factors for consideration in dealing with soil gas surveys can also be
shown and discussed from this data: (1) Calibration with established production, (2) Width
of productive fairway in relation to sample density of the reconnaissance survey, and (3)
Delineation of Morrow gas fairways.
Page 7
K387
19
K413
15S42W
K412
15S43W
15S41W
21
20
19
K464
30
K391 K391A
K390
K393
K392
K394
K395
K418
K417
K416
19
20
K41
219
19
K437
28
29
30
25
K415
24 K414
K439
36
K389
K386
15S42W
24
15S42W
15S43W
15S42W
15S41W
K385
K388
K440
K443
K442
K441
K445
K444
K44
K446
K438
30
K470
K469
K468
K467
25 K466
K465
29
K471
Calibration With Established Production
28
30
K492
K491
K489
K496
K495
K494
K493
K497
K498
K49
K490
LEGEND
ETHANE
CONCENTRATIONS
33
32
31
(ppb)
K517
(Modified after Schumard, 1991)
K541
K518
25 - 30
20 - 25
15 - 20
< 15
5
K571
8
K623
13
16S42W
16S43W
16S41W
14
K676
1000
Scale - Feet
2000
K545
K57
2 4A
K575
K595
K596
K597
K625
K626
11
K627
K647
K648
K649
K546
K547
K549
K548
K550
K55
K576
K580
K578
K577
1
6
K598
K599
K600
K603
K602
K601
K629
K628
12
K630
K631
7
K677
K650
K651
K652
K653
K655
K654
17
K678
18
0
33
K624
K646
5
17
K524
8
7
12
K544
K543
K574
16S41W
11
K523
K522
32
K573
2
K594
3
K521
31
K542
6
1
K520
K519
31> 30
5
2
36
16S43W
1982
36
1983
311984
1985
1986
1987-1988
K679
14
K680
13
K681
16S42W
Year Well Completed
Figure 6 illustrates ethane soil gas concentrations over SW
Stockholm Field and shows why caution should be used
when selecting productive areas for calibration purposes.
The production at SW Stockholm Field, as shown in Figure
6A, was first established in the southern portion of the
field where wells were completed between 1982 and 1984
(Shumard, 1991). The area had reached the end of primary
recovery and was in initial stages of waterflood when the
soil gas survey was conducted in 1987. This means that
the original reservoir pressures had been greatly reduced
(from 1038 psi to 300 psi) in the southern area and the light
gases that did reach the surface in this area were very low
magnitude. In contrast, the wells in the central part of the
field were completed during 1985 and 1986. Compare the
soil gas magnitudes (Figure 6B) in the southern portion of
the field with those in the central part of SW Stockholm Field
where the wells had been producing a much shorter period
of time. The low ethane magnitudes observed over the north
part of the field are discussed in the following section.
K682
K684
K683
18
0
1000
2000
Scale - Feet
Figure 6
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 8
B. SW Stockholm Field Width of Incised Valley
A. Contour Map of Ethane Concentrations (ppb)
K387
K385
24
15S42W
15S43W
15S41W
K419
21
21
20
19
K440
K443
K442
K441
K445
K444
1760 FT
K44
K446
Width of Productive Fairway in Relation to Sample
Density of a Reconnaissance Survey
2460 FT
25
K465
30
K470
K469
K468
K467
K466
29
K471
28
30
25
30
29
28
32
33
As discussed in the previous section, low soil gas magnitudes
were observed over the north part of SW Stockholm Field,
however, this was not due to depleted reservoir pressures.
The wells in this part of the field were completed in 1987 and
1988 (Figure 6A) which was during and after the time the
soil gas survey was conducted. Figure 7 illustrates one way
that a reconnaissance survey, with widely spaced soil gas
sites, can fail to detect gas microseepage from a subsurface
petroleum accumulation. The width of the incised Morrow
valley at the extreme north end of SW Stockholm Field is
only about 2000 feet (0.38 miles) wide compared to 6500
feet (1.23 miles) wide in the central part of the field. The
spacing between the soil gas sites in this area is 1760 feet
in an east-west direction and 2640 feet apart in north-south
directions. Additionally, the orientation of the north end
of the field is northwest-southeast which caused the field
to transect the survey grid at the point of widest spacing
between sample sites.
30
K492
K496
K495
K494
K493
K497
K498
2000 FT
WIDE
K49
K490
ETHANE
CONCENTRATIONS
(ppb)
K518
36
K520
K519
K521
31
K523
K522
32
K524
33
K541
31
36
31> 30
31
25 - 30
20 - 25
15 - 20
< 15
LEGEND
K544
K543
K545
K546
K547
K549
K548
K550
K55
Soil Gas
Site
Location
K542
5
K574
K574A
2
K575
K595
K596
K597
K576
5
K580
K578
K577
1
6
2
K572
K573
K594
K598
K599
K600
6
1
Because of both the width and the orientation of the north
end of SW Stockholm Field, compared to the sample
spacing of the reconnaissance soil gas survey, there were
only low to moderate soil gas concentrations detected at
sample sites over the field in the north area. These same
circumstances also occurred at Second Wind Field to the
southwest of SW Stockholm Field.
K603
K602
K601
6500 FT
WIDE
8
8
K625
K626
11
K627
K647
K648
K649
K629
K628
12
K630
K631
7
11
12
14
13
7
K624
K650
K651
K652
K653
K655
K654
17
K680
13
K681
K677
K682
K684
K683
18
0
1000
Scale - Feet
2000
16S42W
14
16S43W
K679
16S41W
K678
16S42W
16S43W
17
16S41W
K646
K676
20
K438
K491
K623
K418
K417
K416
19
19
K489
K571
K415
24 K414
19
K437
K517
K39
K394
15S42W
15S42W
15S43W
15S41W
K413
K439
K464
K389
K393
K392
K386
15S42W
K412
K388
K391 K391A
K390
18
0
1000
2000
Scale - Feet
Figure 7
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 9
Delineation of Morrow Gas Fairways
B. Frontera Oil Field (1987) and W. Stockholm Gas Field (1979)
7
12
1
6
8
9
10
11
12
7
17
16
15
13
18
14
1
6
12
7
13
18
5
4
3
8
9
10
17
16
15
FUNK
FRONTERA
OIL FIELD
23
24
19
29
28
27
26
25
30
33
34
35
36
31
2
1
21
25
30
29
28
27
36
31
32
33
34
14S42W
14S41W
32
20
5
4
3
4
5
6
1
6
9
20
21
15
20
Figure 8C shows a contour map of the ethane soil gas magnitudes over the field area.
The anomalous ethane microseeps very clearly defined the limits of the subsurface gas
accumulation. Although this is not very significant production, it is interesting to note that
the 1987 reconnaissance soil gas survey (designed for Morrow oil exploration) also clearly
detected gas microseepage from this structural accumulation, even eight years after
production had commenced. It is intriguing to postulate that if TXO had conducted this
reconnaissance soil gas survey in 1979, not only would they have detected the W Stockholm
gas field, but, also would have had an indication of Morrow oil potential (from the Stateline
Trend soil gas anomalies) a full eight years before actual discovery and development of SW
Stockholm Field.
29
30
3
DISCOVERY WELLS
MORROW OIL
1987
MORROW GAS
1979
12
7
13
18
24
19
9
8
10
7
12
C. Ethane Concentrations (ppb) Contour
Map
K285
K286
STOCKHOLM WEST
14
19
13
18
24
19
16
17
K278
15
K279
K281
K280
K284
K282
K287
K283
This example illustrates two important points: (1) The spacing of the soil gas survey was
considered a reconnaissance grid for targeting Morrow oil fairways, however, in a gas fairway
with 640-acre gas units, this particular spacing would be considered a detail grid. (2) There is
no direct relationship between the magnitude of a surface seep and the resultant volumetric
hydrocarbon production or economics of a corresponding well or field. Compare the soil gas
anomaly over W Stockholm Field to the soil gas anomaly over Fronterra Field one mile to the
west. Both soil gas anomalies exhibit similar ethane magnitudes and areal extent (Figure
8C), however, the resultant hydrocarbon production from the two subsurface reservoirs is
very different. W. Stockholm Field has a cumulative production of only 283 MMCFG and is a
depleted field. The average per well gas recovery was only 71 MMCFG. Fronterra Field, on
the other hand, has a cumulative production of 3.7 MMBO. To date, the average per well oil
recovery is 107,000 BO. Secondary recovery efforts are still underway at Fronterra Field.
28
29
30
15S43W
25
15
14
6
7
12
18
13
K330
K332
K331
K333
K336
K337
K338
K339
K334
K357
5
2
1
6
5
11
12
7
8
K358
13
K359
18
K362
18
13 K361
8
K387
K381
K382
K383
K384
K385
K363
K364
17
K390
K391 K391A
K360
K388
K389
K386
17
14
13
18
17
09
K433
61
K410
K434
K462
K411
K412
24
K435
K436
K463
25
19
K437
K464
K415
K438
K465
K439
25 K466
K440
K441
K467
30
K442
Critique of Soil Gas Survey
K417
K416
19
K413 24 K414
15S42W
16
11
1
K312
8
K311
K310
7
K309
34
6
2
16S42W
7
10
33
16S42W
9
3
12
27
31
16S43W
4
36
16S41W
5
35
32
31
36
34
K308
K335
STOCKHOLM
33
7
30
K329
32
K307
COLORADO
KANSAS
25
K306
12
K305
15S41W
26
04
15S43W
27
22
15S42W
28
D
EN
TR
29
21
20
15S42W
23
15S42W
22
15S41W
NE
LI
TE
16
11
A
ST
17
10
24
30
FRONTERA
8
18
25
25
14S43W
14S42W
ARAPAHOE
19
13
22
19
24
24
15S42W
22
18
KANSAS
21
COLORADO
20
13
TXO completed the discovery well for the field in April 1979. The Morrow gas reservoir was
encountered at 5042 feet with 16 feet of net pay. The four-well gas field was developed on
640-acre spacing (Figure 8B). It appears that four dry holes were also drilled to delineate the
limits of the field. Cumulative production, since 1979, from the four wells in this field has only
been 283 MMCFG. The last reported production was in 1998. This gas field, considering the
marginal cumulative gas production over a 21-year period and the eight wells drilled to define
the field, would be considered as a non-commercial venture by most oil company economic
guidelines.
15S42W
2
15S41W
3
17
15S43W
4
COLORADO
KANSAS
A. Location Map
5
W. STOCKHOLM
GAS FIELD
7
12
About a decade before the discovery and development of the Morrow Stateline Trend,
TXO had conducted an exploration effort which targeted Morrow gas on low-relief Morrow
structures in the general vicinity of the Las Animas Arch. One of the subsequent TXO Morrow
gas discoveries in 1979 was the W. Stockholm (Morrow) gas field shown in Figures 3A and
8A.
8
20
K443
K
K469
K468
29
30
ULTIMATE RESERVES
FRONTERA FIELD
6,200,000 BO
W. STOCKHOLM FIELD
283 MMCFG
K494
K495
K4
Figure 8
How to Design an Exploration Surface Soil Gas Geochemical Survey
As early as 1987, the soil gas survey accurately defined the general areal extent of the
productive Morrow incised valley fairway, as would be confirmed by development drilling three
years later in 1990. It can also be discerned that, at the particular sample density, the soil
gas data could not have been used to determine 80-acre drilling sites. Additionally, because
of the selected sample density, the very narrow portions of the incised valley (north part SW
Stockholm and Second Wing) were not readily discernable. Therefore, the selected sample
density was at the minimum threshold required to provide useful exploration information.
The soil gas survey also appears to have detected microseepage from the Morrow gas and
Mississippian oil fields in the area.
Page 10
DETAILED SOIL GAS SURVEYS OVER THE SOUTH STATELINE OIL
TREND
432
433
429
434
367
370
368
369
336
339
410
337
338
340
397
412
411
414A 415
416
413 413A
31
414
32
CHEYENNE CO
KIOWA
CO
345
346
344
435
436
438
437
323
5
419
418
417
420
421
422
371
372
356
578
570
579
398
401
NORTH
STATELINE
SURVEY
400
18
156
152
598
141
142
143
596
24
FRONTERA
19
286
288
Wallace Co.
291
594
595
285
295
562
287
672
673
683
138
139
137
140
MT. SUNF
STOCKHOLM
SOUTHWEST
313
311
312
167
166
172
12
165
164
171
170
168
126
122
123
555
281
278
279
274
275
8
9
302
173
169
303
174
175
Surface Soil Gas Geochemistry
271
270
119
120
272
269
118
121
265
268
13
18
17
16
19
20
21
29
28
32
33
A Denver-based independent oil company decided to explore for Morrow
oil in the Stateline Trend on a regional level and attempt to increase the
drilling success rate by using surface soil gas geochemistry. The company
first purchased a reconnaissance soil gas data set in the north part of the
trend and later conducted a new detailed soil gas survey in the south area
as shown in Figure 9A. At the time of the new survey (April 1992), the
development drilling had been completed at Second Wind field and there
were only three development wells at Moore-Johnson field in the south.
The two combined soil gas surveys provided soil gas microseep data
consisting of 1817 samples covering a total area in the Morrow Trend of
203 square miles.
648
682
20
301
304
256
257
260
261
264
255
258
259
262
263
116
115
104
103
099
100
112
113
114
112A
113A
114A
105
102
098
101
147
266
267
136
23
280
7
649
660
117
277
125
124
556
564
146
290
309
308
135
284
24
134
282
283
129
130
111
30
25
29
273
128
276
131
Greeley Co.
244
248
255
109
254
251
247
250
239
242
243
246
108
253
252
248
249
240
241
244
245
092
093
094
095
096
097
082
081
091
090
089
088
087
086
083
080
132
26
084
247
110
107
133
106
245
246
249
254
250
253
274
275
257
256
251
243
242
241
238
239
240
258
263
271
268
238
235
234
231
262
270
269
237
236
233
232
236
SIDNEY
184
164
181
183
182
155
150
151
1
160
153
154
252
152
126
259
237
36
123
231
229
230
180
179
149
148
147
122
177
176
178
142
143
145
120
282
283
157
175
174
140
144
146
141
121
119
158
173
091
285
172
006
188
009
008
184
012
011
187
138
169
139
086
087
185
181
136
135
137
168
166
171
167
170
SJ10
SJ11
039
117
084
001
082
003
318
183
035
13
013
010
015
014
SJ16
SJ13
SJ14
SJ12
SJ03
SJ06
043043A
228
229
072
227
230
219
222
223
226
309
068
072
075
036
016
017
SJ04
SJ05
SJ01
066
070
064
5
4
003
217
216
213
212
209
208
061
060
005A
218
215
214
211
210
207
062
063
206
059
058
056
057
208
204
205
205
210
209
207
206
054
055
214
213
202
201
052
051
048
047
013A
215
212
203
200
053
050
049
046
014A
014
219
216
199
196
201
200
197
506
289
306
009
009A
288
298
299
012
012A
011A
322
070
211
006 006A
010
010A
071
290
305
008
050
321
067
069
225
007
12
053
224
221
323
015
8
7
9
129
066
016
065
204
511
507
510
508
509
512
601
602
203
073
064
074
063
032
031
061 062
055
100
030
056
054
017A
017
218
217
199
198
505
020020A
226
225
194
193
190
191
194
195
501
504
023
021
021A
227
224
195
192
189
192
193
196
502
503
514
513
223
220
191
188
038
041
042
045
522
521
517
518
222
221
190
189
039
040
043
044
202
18
13
14
197
198
018
019
095
131
17
16
097
20
099
098
132
133
134
060
057
059
058
111
110
108
109
033
029
028
113
114
027
R 41 W
R 42 W
30
025
101101A
103
102
24
112
107
105
106
018
26
25
032
026
031
030
534
531
619
533
30
532
620
638
637
636
633
29
JACE
MOORE-JOHNSON
019
104
029
631
709
630
629
519
20
19
R 42 W
25
024
026
23
SOUTH STATELINE
SURVEY
022A
022
R 43 W
19
KIOWA CO
GREELEY CO
096
24
027
023
520
516
515
21
022
607
608
604
603
606
033
610
609
605
618
615
527
530
614
611
523
526
621
617
29
616
528
529
613
524
525
635
704
703
702
028
025
622
024
021
020
28
612
724
726
727
38:27:
543
544
-101:57:30
699
700
701
725
729
728
545
546
627
718
719
720
733
730
731
640
639
626
721
734
710
732
641
642
548
547
549
550
634
Area of Moore-Johnson Field
628
623
624
723
722
535
536
537
538
705
706
553
552
542
541
540
539
708
707
554
551
625
645
644
646
643
Figure 9
How to Design an Exploration Surface Soil Gas Geochemical Survey
The detailed soil gas survey in the south part of the trend, consisting of
1034 sites, was conducted over a very large area (53 square miles) from
just southeast of Second Wind field in Cheyenne County, Colorado to two
miles south and five miles southeast of Moore-Johnson field in Greeley
County, Kansas (Figures 9A and 9B).
287
013
093
SJ02
130
SJ08
065
004
308
310
049
049A
220
001
094
037
067
071
6
307
044
044A
303
069
068
315
042
304
301
17
18
SJ07
31
073
075
1
314
045
312
079
078
092
076
034
074
034
002
041A
046
051
302
11
182
319
052A 052
080
035
292
311
316
002 005
048
320
SJ09
264
267
277
313
115
115A
004
317
081
077
SJ15
266
T 18 S
047
116
294
118
036
040A
280
293
085
083
090
2
296
286
8
7
265
276
279
291
090A
295
300
12
007
186
272
037A 037
038
297
284
128
159
261
273
278
281
089
127
156
260
T 17 S
124
088
162
161
232
228
5
6
187
163
233
125
COLORADO
KANSAS
165
185
077
076
235
35
186
078
079
32
31
36
30
25
234
085
Detailed soil gas surveys typically are conducted over a large area
with a much denser spacing between soil gas sample sites than in a
reconnaissance survey. The soil gas samples in a detailed survey may
either be collected as infill in an area with previous sampling collected on
a reconnaissance grid spacing or they may be collected in a new area with
no previous sampling. Soil gas data collected years apart in the same area
have been documented to be fully compatible with one another (Jones et
al., 1985, Dickinson and Matthews, 1993). The example discussed in this
case was conducted over the southern portion of the Morrow Stateline
Trend in 1992.
650
659
14
127
687
686
684
310
651
297
557
563
145
289
685
298
658
582
148
674
292
593
678
306
307
652
657
294
558
153
675
144
597
4
653
299
559
293
296
150
676
677
160
561
583
584
154
157
STOCKHOLM WEST
585
599
656
163
17
149
151
5
589
588
587
586
155
6
654
300
566
560
158
404
405
399
689
688
13
717
655
11161
162
565
716
698
385
680
376
567
568
159
403
402
697
690
691
384
381
679
180
681
375
574
581
580
382
575
430
335
332
328
379
380
377
592
374 305
387
1
590
362
661
390
316
378
591
363
365
693
361
360
663
366
576
577
355
354
647
431
331
692
33
32
31
314
2
671
8
695
694
T 17 S
349
357
569
424
334
333
329
T 16 S
389
348
358
36
664
670
669
668
7
330
383
347
359
425
426
711
600
12
391
386
326
364
ARAPAHOE
327
315
394
325
662
665
666
667
318
393
388
350
571
423
428
427
440
696
319
392
322
351
317
572
573
715
714
439
712
-101:57:30
38:37:
176
321
177
320
35
352
353
713
178
179
342
6
1
395
324
341
343
396
R 43 W
407
R 42 W
406
409
GREELEY CO
R 42 W
R 41 W
36
FUNK
408
Realizing the limitations of the northern reconnaissance survey spacing
(11 sites per section), this company increased the basic sample density in
the southern survey to 16 sites per section (40-acre spacing). In addition
as shown in Figure 9B, the company already had several prospects in the
survey area and elected to increase the sample density in these areas over
the standard spacing of 16 sites per section.
The high-density soil gas survey in the vicinity of Moore-Johnson field
(Figure 9B) consisted of 106 sample sites over a four square mile area (24acre spacing). It is this area which will be the focus of this paper.
The purpose of the regional detailed soil gas survey was threefold: (1)
calibration of the soil gas survey to the production at Moore-Johnson field,
(2) to aid in further exploitation and development drilling at Moore-Johnson
field, and (3) to determine other areas along trend that exhibited similar
anomalous soil gas microseepage and therefore would have Morrow
exploration potential.
Page 11
Colorado
Kansas
Smokey Hill
Cheyenne County
5
Bledsoe Ranch
Wildfire
Harker Ranch
"ST
AMOCO
LAWSON #1
02/90
ATE
Sianna
Castle Peak
Discovery of Moore-Johnson Field and Early Development Drilling in 1990
KANSAS
Speaker
COLORADO
Sherman County
Wallace County
Lookout
ET
LIN
Arapahoe
ND
RE
Mt. Pearl
Sorrento Field
"
Frontera
Mount Sunflower
Arrowhead
Stockholm SW
Second Wind
1
2
Greeley County
Sidney
Cheyenne County
Kiowa County
The Amoco combined geological and seismic conceptual model was that of a northwestsoutheast oriented Morrow sand body (Figure 10B). The location for the discovery well
was determined by identification of the basal upper Morrow fluvial incised valley on 2-D
seismic lines supplemented by data from available well control (Adams, 1990). By May
1990, Amoco had extended the field to include three wells (Figure 10C). The Brewer #1
and Brewer #2 flowed at rates of 670 and 350 BOPD, respectively. In the first four months,
the Moore-Johnson #1 produced 30,000 BO.
Jace
nty
Moore-Johnson
Salt Lake/Haswell
0
McClave
0
10
20
30
12
0
Greeley Co., Kansas
5
JACE FIELD
10
10
10
8AMOCO
KELLER #1
11/90
36
AMOCO
BREWER #3
06/90
17S43W
18S43W
Kiowa Co., Colorado
6
km
35
17S41W
18S41W
1
mi
0
AMOCO
BREWER 2
05/90
AMOCO
KELLER #2
11/90
2
8
Discovery Well
30
17
12
18S41W
18S43W
17
14
AMOCO
LINN 1
10/90
13
AMOCO
MO-JO 1
07/89
AMOCO
MO-JO 2
09/90
30
18
0
1000
This was a very significant Morrow discovery in that it extended Morrow production for a
distance of 10 miles to the south from Second Wind field of the Stateline Trend. Amoco
attempts at further development drilling was another story, however.
As shown in Figure 10C, attempts to extend the field to the south by Amoco in 1990
resulted in three dry holes (Moore-Johnson #2, Linn #1, Sell #1). Two successful Morrow
development wells were completed by Amoco to the northwest of the discovery well in
March and May of 1990 (Brewer #1, Brewer #2). Attempts by Amoco to extend the field
farther to the northwest resulted in three more dry holes (Keller #1, Keller #2, Brewer #3).
Amoco also drilled another dry hole to the northeast in February 1990 with the Lawson
#1.
AMOCO
BREWER 1
03/90
11
13
12
11
1
20
7
Moore-Johnson field in Greeley Co., Kansas was discovered by Amoco in October 1989
(Adams, 1990). At the time of the discovery, the Stateline Trend had been developed
to the extent shown in (Figure 10A). The Amoco Moore-Johnson #1 was the discovery
well for the field and was completed for 522 BOPD (Figures 10B and 10C). The well was
completed in the sands of the V-7 valley fill sequence of the Morrow Formation. This
equivalent interval in the Morrow Formation was initially named the Stockholm Sand
during development of SW Stockholm field to the north. The sequence stratigraphy of
the Morrow in relation to reservoir geology in the vicinity of Moore-Johnson field has been
more recently discussed by Bowen and Weimer (1997, 2003).
14 AMOCO
13
SELL 1
03/90
The overall success rate, at the end of 1990, for development drilling in the MooreJohnson field area was a disappointing 33%. This was considerably below previous
industry standards in the Morrow Trend. Success rates for development of Frontera,
SW Stockholm and Second Wind fields of the Stateline Trend were 73%, 68%, and 56%,
respectively. There was no further drilling in the field area during all of 1991.
As will be shown later in the paper, had Amoco used soil gas geochemistry, in conjunction
to seismic and subsurface geology, the six dry holes could have been avoided.
2000
Scale - Feet
Figure 10
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 12
230
39
5
121
283
282
41
63
KANSAS
COLORADO
5
41
KANSAS
COLORADO
124
58
42
65
119
71
279
277
37
47
75
75
87
090
090A
46
148
285
295
121
26
2
59
AMOCO
#1
AMOCO
BREWER #3
083
080
88
97
83
115
AMOCO
KELLER #2
AMOCO
077 2
BREWER
49
078
079
61
42
215
65
40
311
309
47
26
48
001
002
005
082113
36
217
003
124
319
312
76
29
081
59
88
318
200
083
080
88
97
048
113
11
303
76
70
61
42
215
050
108
12
053
071
38
78
321
304
106
99
076
54
049A
83
203
302
078
310
049
96
079
044
83
046
103
051
052A 052
77
115
301
36
83
069
068
067
65
30
48
070
30
093
35
35
AMOCO
MO-JO 1
17
129
76
072
95
17
075
18S41W
18S43W
22
072
76
77
95
075
066
34
77
094
22
130
073
074
73
52
063
47
40
AMOCO
LINN 1
129
066
34
AMOCO
MO-JO 2
094
1000
042
35
045
115A
143
20
316
19
093
0
65
004
197
49
48
36
75
077
30
314
317
78
067
65
313
80
053
068
043
58
300
092
AMOCO
076
BREWER 1 069
36
047
115
118
320
092
095
27
83
101
12
11
116
43
197
049
96
117
84
51
052A
59
34
084
051
1
292
42
51 KELLER
041A
44
23
294
8
046
103
94
280
296
095
13
14AMOCO
SELL 1
18S41W
18S43W
084
048
113
040A
42
45
286
75
039
293
087
128
081
037
69
110
291
085
8
036
62
037A
62
71
53
002
113
161
297
127
109
276
50
284
47
1
278
038
089
091
2
281
135
088
123
124
76
130
073
074
52
063
73
47
40
13
14
061
061
57
57
2000
Scale - Feet
0
1000
Soil Gas Calibration Survey and Detailed Survey in Moore-Johnson
Field Area
A soil gas calibration survey was first conducted over the three-well field and in the area of
the 6 dry holes in April 1992 (Figure 11A). Because the field was being developed in 40acre units, a sample density of 16 sites per section was selected. An ethane magnitude
contour map of the soil gas data in the calibration area is shown in Figure 11A. As shown
on the ethane magnitude contour map, low ethane magnitudes were observed in areas
where the dry holes were drilled and the anomalous ethane values corresponded to the
area of the three Morrow oil wells. There was no problem with reservoir pressure depletion
at the time of the survey because of the limited production at that time.
The soil gas contour map for the calibration survey also indicated other areas of anomalous
microseepage to the east and northeast of the three productive wells. The more detailed
soil gas survey was extended into those areas to aid in further development drilling at
Moore-Johnson field.
The initial sample grid of 16 sample sites per section was increased with infill soil gas
sites as shown in Figure 11B. A total of 106 soil gas sites were sampled within the
map area. The infill sample data significantly increased the detail of the microseepage
anomaly pattern from that of the original calibration survey, as evidenced by comparing
the two contour maps. Ethane magnitudes ranged from 22 ppb to 205 ppb within this area.
The ethane magnitude contour map indicated anomalous microseepage over the Axem
Resources and Murfin Drilling (Axem/Murfin) lease block in sections 2, 11, and 14.
The surface soil gas geochemical data was next integrated with the combined subsurface
geology and seismic interpretations.
2000
Scale - Feet
AXEM/MURFIN LEASES
ETHANE
CONCENTRATIONS
(ppb)
> 125
110 - 125
90 - 110
75 - 90
65 - 75
< 65
Figure 11
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 13
AMOCO
LAWSON #1
TD 5350
5
121
58
127
53
REGIONAL DIP
087
42
Proposed Location
Axem/Murfin
Coyote #1
18S41W
18S43W
AMOCO
LINN 1
TD 5300
0
1000
320
19
316
47
002
082113
36
005
217
003
124
319
76
11
076
215
069
65
12
071
38
321
83
304
106
068
30
050
108
053
78
067
48
070
30
093
35
17
129
76
072
95
075
34
066
77
094
22
A
AMOCO
SELL 1
TD 5300
095
27
13
130
73
073
52
074
47
063
40
13
14
061
57
0
2000
1000
2000
Scale - Feet
Scale - Feet
(ppb)
Limits of
Incised Valley
Morrow B Sand
Productive
Morrow B Sand
Thin, Oil Show
Limits of
Morrow Sands
Morrow A Sand
Productive
Axem/Murfin
Leases
How to Design an Exploration Surface Soil Gas Geochemical Survey
> 125
110 - 125
90 - 110
75 - 90
65 - 75
< 65
-1500
During the first half of 1992, Axem/Murfin integrated the combined subsurface geology and seismic
interpretation with the surface soil gas data. The conceptual model for the Morrow trend, derived
from the all the development of the northern Stateline Trend fields, was that the Morrow section (base
of Atoka to top Morrow Limestone) was observed to thicken in the areas of maximum Morrow sand
development and productive wells. In contrast, the Morrow section was much thinner, with nondeposition of Morrow sands, on the east and west flanks of the Morrow fields. This was the Axem/
Murfin conceptual model at the Moore-Johnson area interpreted from the available well control and
seismic data. The well control available at that time is shown in Figure 12A.
Subsurface data from the 10 Amoco wells in the area and seismic interpretation provided the Axem/
Murfin concept of the Morrow incised valley boundaries, regional dip, and general axis of the depocenter
of the Morrow valley as indicated on Figure 12A. Amoco had established production from 2 different
Morrow sands (named “A sand” and “B sand”) in their three wells. The Morrow completion zones in
the three wells are as indicated on Figure 12A. Additionally, the Morrow “B sand” was encountered in
three other Amoco wells with oil shows, however, the porosity/permeability and thickness of the sand
precluded completion attempts in those wells. The Morrow sands were not present in the other four
Amoco wells. The expected areal distribution of Morrow sands was interpreted as shown on the map.
Axem/Murfin had interpreted the Morrow sands to be oriented north-south in the area as opposed
to the previous Amoco concept of a northwest-southeast alignment. In the new interpretation, the
Amoco productive wells were interpreted to be at the west, updip limits of a Morrow stratigraphic trap
(Figures 12A and 12C).
The interpretation of the soil gas survey data is shown on Figure 12B. The ethane magnitude
contour map indicated that the maximum gas microseeps were observed in the central portion of the
expected Morrow incised valley and within the expected Morrow sand fairway (Figures 12A and 12B).
The geochemical, geological, and geophysical data were all compatible with the conceptual model
for a Morrow stratigraphic trap.
ETHANE
CONCENTRATIONS
LEGEND
TD 5305
Integration of Subsurface Geology, Seismic, and Surface Soil Gas Geochemistry
310
54
049A
83
203
079
42
TD 5350
044
83
303
70
302
76
MISSISSIPPIAN
-1400
309
48
049
MORROW LM
-1300
042
35
312
29
301
99
092
36
65
046
103
051
96
ATOKA
-1100
-1200
314
65
045
40
048
113
AMOCO
LAWSON #1
043
311
26
078
61
077
49
AMOCO
MO-JO 1
TD 5290
14
004
197
AMOCO
BREWER #1
TOP MORROW
1
292
59
047
58
115
115A
143
20
052A 052
77
115
080
97
12
AXIS OF THICK
MORROW SECTION
11
AMOCO
MO-JO 2
TD 5300
A
318
200
18S41W
18S43W
17
081
59
083
88
AMOCO
BREWER 1
TD 5330
Discovery Well
001
88
084
51
AMOCO
BREWER #3
TD 5300
AMOCO
KELLER #2
TD 5290
317
75
041A
44
313
36
294
197
118
101
300
80
040A
94
116
83
-1000
DATUM
A’
SOIL GAS
ANOMALIES
277
87
280
23
293
45
2
296
84
128
75
8
KELLER #1
TD 5360
039
42
117
43
286
34
085
109
8AMOCO
AMOCO
BREWER 2
TD 5250
295
26
037
69
110
A
A’
036
62
037A
279
75
090
090A
46
148
285
121
276
161
278
50
291
75
297
47
123
124
038
62
089
71
284
37
119
71
1
281
135
088
65
091
47
2
230
76
42
282
63
283
41
KANSAS
124
41
COLORADO
5
A’
KANSAS
COLORADO
39
Figure 12
The Axem/Murfin acreage position was excellent. A location was staked for the Axem/Murfin Coyote
#1 in section 2. The well was spudded July, 25, 1992
Page 14
39
WITT A-1
AXEM
BOBCAT 2-2
AMOCO
LAWSON #1
5
AXEM
BOBCAT 2-2
121
58
2
WITT B-1
119
71
1
AXEM
COYOTE 2
285
121
087
42
WENDLEBURG 2-11
8
084
51
WENDLEBURG 3-11
BREWER 2
081
59
318
200
KELLER #1
BREWER 3
BREWER 1
AXEM
WENDLEBURG 1-11
12
320
19
HUDDLESTON 33-11
KELLER #2
077
49
BREWER 2
YATES
WILLIAM #1
BREWER 1
005
217
003
124
11
076
215
069
65
65
314
65
042
35
045
40
048
113
312
29
310
54
049A
83
203
321
83
067
48
MO-JO 1
17
129
76
AXEM
MO-JO 3
LINN 1
14
SELL 1
095
13
18S41W
18S43W
18S41W
18S43W
DUNCAN ENER.
ABEL #1
075
34
SELL #13-3
130
73
073
52
074
47
0
2000
1000
In November 1992, Axem/Murfin completed two Morrow wells with the
Wendleburg #1-11 and Blackbird #1 wells. The Wendleburg #1-11 location was
supported by a strong soil gas anomaly.
5
In December 1992, HGB Oil completed the Brewer #1 as a Morrow oil well. This
location had been proven by the preceding surrounding wells to the west, east,
and south.
6
HGB Oil, Yates, and Duncan Energy each drilled a Morrow dry hole in Colorado
attempting to extend field production updip and to the west. There were now five
dry holes in Colorado to the west of the field. All five well locations are in areas
of low magnitude soil gas data.
13
14
57
1000
4
063
40
061
0
Duncan Energy completed two direct offsets in October and November to the
Amoco Brewer #1 and #2 producing Morrow wells. These two wells were only
1500-foot offset locations.
066
77
094
22
AXEM
MO-JO 4
MO-JO 2
072
95
3
070
30
093
35
17
In August 1992, Axem/Murfin drilled their first well and completed the Coyote #
1 as a Morrow oil well (Figures 13A and 13B). This was a very significant well
in that it was a 4700-foot step-out extension for Moore-Johnson field. The well
location was supported by a strong soil gas anomaly. The well confirmed the
conceptual model established by integrating geochemistry with geology and
geophysics.
071
38
304
106
068
30
2
12
053
78
079
42
In April and May 1992, MW Pet. drilled two Morrow dry holes with the Brewer
#24-2 and Sell #13-31 wells. Both wells were 4000-foot step-outs. Both well
locations are in areas of background soil gas concentrations. No further wells
were drilled by this company in this area
050
108
049
303
70
302
76
1
044
83
046
103
051
96
Eleven wells were drilled in 1992 by 5 oil companies (Figure 13A). Only Axem/Murfin
used the integrated approach of soil gas geochemistry with geology and seismic to
select well locations. The locations of the wells drilled in 1992 are shown on Figure
13A. An ethane magnitude contour map (Figure 13B) illustrates the geochemical basis
of Axem/Murfin decisions in selecting well sites. The following is the order in which the
1992 wells were drilled:
309
48
311
26
319
76
078
61
043
313
36
301
99
092
36
HUDDLESTON 34-11
002
082113
36
052A 052
77
115
080
97
083
88
11
001
88
316
47
1
292
59
047
58
115
115A
143
20
1992 DRILLING - MOORE-JOHNSON FIELD
041A
44
280
23
294
197
004
197
277
87
040A
94
116
83
118
101
317
75
300
80
037
69
110
039
42
117
43
128
75
BREWER 24-2
2
036
62
037A
279
75
293
45
296
84
286
34
085
109
8
295
26
127
53
AXEM
BLACKBIRD #1
AXEM
COYOTE 1
HGB OIL
MILLER #1
090
090A
46
148
276
161
278
50
291
75
297
47
123
124
038
62
089
71
091
47
AXEM
BOBCAT 1-2
WITT A-2
281
135
088
65
284
37
230
76
42
282
63
283
41
KANSAS
5
KANSAS
COLORADO
124
41
COLORADO
LANG 34-35
2000
Scale - Feet
Scale - Feet
LEGEND
Previous Wells 1993-94 Completions
OIL
WELL
OIL/GAS
WELL
DRY
HOLE
DRY
HOLE
1989 - 1990
1992
1993
1994
ETHANE
CONCENTRATIONS
By the end of 1992, Moore-Johnson field had produced 512,714 BO.
(ppb)
> 125
110 - 125
90 - 110
75 - 90
65 - 75
< 65
Figure 13
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 15
1993 and 1994 DRILLING - MOORE-JOHNSON FIELD
The locations of all the wells previously drilled through 1992 are shown on Figure 13A.
An ethane magnitude contour map (Figure 7B) illustrates the basis of Axem/Murfin
decisions in selecting well sites. The following are the 1993 wells that were drilled:
1
Marathon completed the Wendleburg #2-11 as a Morrow oil well in February
1993. This well was a direct offset to the Axem/Murfin Wendleburg #1-11 drilled
three months previously in November 1992. This was the only lease Marathon
held in the field area.
2
HGB Oil drilled three Morrow oil completions from March through July 1993 (Witt
#A2, Witt #B1, Brewer #2). The wells were on the updip, west side of the field.
The Witt #B1 only produced 1745 BO and is considered to be a dry hole.
3
Axem/Murfin drilled three Morrow oil wells in the north area with the Bobcat #1-2,
Coyote #2, and Wendleburg #3-11. The Bobcat and Wendleburg well locations
were in areas of anomalous microseeps.
4
Axem/Murfin drilled two Morrow oil wells in the south area with the MoooreJohnson #3 and Moore-Johnson #4 wells. The Moore-Johnson #3 well was
completed in August 1993 and was located in an area of anomalous ethane
concentrations.
By the end of 1993, Moore-Johnson field contained 17 Morrow oil wells and extended for
11,000 feet in a north-south direction and 3000 feet in width. Axem/Murfin had completed
seven successful Morrow wells without a dry hole. At the end of 1993, cumulative
production at the field was 780,549 BO.
How to Design an Exploration Surface Soil Gas Geochemical Survey
In 1994, four wells were drilled by three oil companies in the north area of the field. The
following are the 1994 wells that were drilled:
5
HGB Oil drilled the Witt #A1 as a Morrow oil well in January 1994. The well
location was on trend and 1500 feet from their Witt #A2 completion 6 months
earlier.
6
Axem/Murfin drilled their first dry hole in the Bobcat #2-2 in January 1994. A 700foot offset to the southwest, however, resulted in a Morrow oil completion. The
Bobcat lease, to date, has produced a total cumulative of 170,646 BO from two
wells.
7
Duncan Energy completed a marginal Morrow well with the Lang #34-35 in
March 1994. After only producing 477 BO, the well was converted to an injection
well.
Moore-Johnson field was fully defined by 34 wells. The major extension of the field only
took 24 months. This is one of the shortest development periods for a comparative size
field in the whole Morrow trend.
By the end of 1994, the cumulative production from the 19 Morrow wells in MooreJohnson field was 980,152 BO.
Page 16
BOBCAT 2-2
BOBCAT 1-2
WITT A-2
1
2
Atokan
BOBCAT 2-2
Morrowan
AMOCO
LAWSON #1
Unnamed Rocks of
Atokah Age
?
Thirteen Fingers
Limestone
Morrow Fm.
WITT A-1
Pennsylvanian
5
A’
KANSAS
COLORADO
LANG 34-35
Upper
COYOTE 2
BREWER 24-2
WENDLEBURG 2-11
8
MILLER #1
WENDLEBURG 3-11
BREWER 2
KELLER #1
BREWER 1
BREWER 3
Chester
Group
V1
V7d
V7c
V7b
V7a
V3
V7
V11
Morrow
Limestone
12
11
KELLER #2
BREWER 1
17
Reservoir:
Lithology:
Type Trap:
A
MO-JO 3
MO-JO 4
18S41W
18S43W
MO-JO 2
ABEL #1
LINN 1
0
1000
LINN 1
LIMITS OF V7
INCISED
VALLEY-FILL
14
SELL 1
13
SELL #13-3
2000
Scale - Feet
Limits and Dimensions of Morrow V7 Sands
Areal Extent
Width
Thickness
Morrow Well
Completion Zones
V7d
0 - 30 ft.
1800 - 2700 ft.
V7d
V7c
0 - 18 ft.
1300 - 2300 ft.
V7c
V7b
0 - 24 ft.
2300 - 3200 ft.
V7b
Figure 14
How to Design an Exploration Surface Soil Gas Geochemical Survey
V3 INCISED VALLEY
-1200
FLOODING SURFACE
V7c
Discovery:
Depth:
Spacing:
Field Size:
Avg. Net Pay:
Porosity:
Permeability:
Water Sat.:
Pressure:
Reserv. Drive:
GOR:
Cum. Prod:
Ultimate Prod.:
MORROW SH
V7 INCISED VALLEY
V7b
V7d
MORROW LM
-1300
TD 5300
10/92
TD 5205
11/92
MISSISSIPPIAN
ST. GENEVIEVE LM
TD 5294
12/93
TD 5350
2/90
-1500
Subsurface Geology and Reservoir Performance
Moore-Johnson Field Parameters
(Revised after Adams, 1990)
MO-JO 1
V1 INCISED VALLEY
TD 5350
3/90
Table 1
HUDDLESTON 34-11
ATOKA FM
ST. LOUIS LM
Warsaw Fm.
Unnamed Rocks of
Kinderhookian Age
AMOCO
LAWSON #1
SEC. 1
KB 3902 (EST)
MURFIN DRLG.
BLACKBIRD #1-1
SEC. 11
KB 3897
AXEM RES.
WENDLEBURG #3-11
SEC. 11
KB 3907
-1100
Spergen Fm.
Unnamed Rocks
of
Osagean
Age
MURFIN DRLG.
WENDLEBURG #1-11
SEC. 11
KB 3918
TD 5270
11/92
St. Louis Fm.
BREWER 2
WILLIAM #1
DUNCAN ENER.
HUDDLESTON #33-11
SEC. 11
KB 3917
-1400
WENDLEBURG 1-11
HUDDLESTON 33-11
-1000
DATUM
AMOCO
BREWER #1
SEC. 11
KB 3898
Ste. Genevieve Fm.
Kind.
Mississippian
COYOTE 1
Osagean
BLACKBIRD #1
Meramecian
Chesterian
WITT B-1
A’
(Bowen & Weimer, 2003)
V9
Lower
A
Morrow
Nomenclature
Morrow V7
Sandstone
Stratigraphic/
structural
Oct. 1989
5100-5200 ft.
40 ac.
1290 ac.
16 ft.
14 to 28%
22 to 9,990 md
13 to 47%
1040 psi
Gas cap expansion/
solution gas drive
107:1 cu ft / bbl
1,729,000 BO
2,000,000 BO
Moore-Johnson field (Figures 14A, 14B, and 14C) has been discussed by Adams (1990) and more recently
by Bowen and Weimer (1997, 2003). These last two papers document the Morrow sequence stratigraphic
framework throughout the trend and relate it to the subsurface geology, reservoir geometry, and reservoir
performance at Moore-Johnson field.
The reservoir sands at Moore-Johnson field were deposited as fluvial valley-fill deposits in a valley incised into
the Morrow Limestone (Figure 14C). These Morrow sands have been correlated regionally to the Morrow V7
valley sequence (Figure 14B). The areal distribution of the three reservoir sands deposited within the incised
valley is shown in Figure 14A. From oldest to youngest, the order of deposition was V7b, V7c, V7d valley fillsequences.
Structural cross section A-A’ (Figure 14C) depicts the positions of the three valley-fill sequences with respect
to depth. Regional dip is to the east-southeast. The various Morrow reservoirs were encountered at depths
ranging from 5100 to 5150 feet. Initial reservoir pressure was 1040 psi. Other reservoir parameters are shown
in Table 1.
The three reservoir sand bodies are predominantly lateral to each other and are rarely incised into one another
as is the case in the northern fields. Generally, the three sand bodies are completely encased in estuarine shales
(Figure 14C). Porosities range from 14% to 28 % with permeabilities from 22 to 9,990 md (Adams, 1990). The
GOR was 107:1 (cu ft/bbl). Other field parameters are listed in Table 1.
Compared to the V7 valley fill reservoirs in northern fields, the reservoirs at Moore-Johnson are narrower in
cross section (see legend, Figure 14A) and of smaller extent and more compartmentalized due to the dominant
shale facies. Because of these conditions, oil columns are thinner and production values are somewhat lower,
however, drainage efficiency is high (Bowen and Weimer, 2003). Recovery factors are variable due to, in some
cases, problems with pressure maintenance.
Oil volumes produced to date from individual wells range from 32,000 BO to over 230,000 BO. The field-wide
average, to date, for the 19 wells is 91,000 BO per well. These per well averages are better than the average
values at Castle Peak, Harker Ranch, SW Stockholm, and Jace fields reported by Bowen and Weimer (2003).
Page 17
LANG 34-35
KANSAS
COLORADO
5
250000
0.5
WITT A-1
LAWSON #1
BOBCAT 2-2
1500000
A. Annual Production
Northern Leases
D. Cumulative Production
Moore-Johnson Field
200000
45.3
BOBCAT 2-2
85.3
1000000
LEGEND
83.3
43.3
CUM. BO x 1000
BO
BOBCAT 1-2
WITT A-2
BO
150000
1
2
100000
500000
COYOTE 2
WITT B-1
54.6
1.7
> 200
BLACKBIRD #1
50000
COYOTE 1
80 - 90
0
40.8
0
1990
1991
1992
1993
1994
1995
BREWER 24-2
WENDLEBURG 2-11 WENDLEBURG 3-11
8 - 80
70
BREWER 2
32.0
6.5
50 - 60
BREWER 1
250000
12
220
229
18S41W
18S43W
LINN 1
B. Annual Production
Southern Leases
1990
220
14
SELL 1
1991
1992
1993
1994
1995
1996
1997
YR
250000
1998
1999
2000
2001 2002
2003
C. Annual Production
Entire Field
200000
13
SELL #13-3
BO
1000
2000
Scale - Feet
100000
Amoco
Axem Murfin
50000
Duncan Energy
HGB Oil
Marathon
How to Design an Exploration Surface Soil Gas Geochemical Survey
0
1990
Figure 15
1992
1993
1994
1995
1996
1997
YR
1998
1999
2000
2001
2002
2003
Annual production for the northern leases (Witt, Bobcat, Coyote,
Brewer, Wendleburg and Huddleston) is shown in Figure 15B. The
peak in production from 1992 to 1995 reflects the addition of the
new development wells. Annual production volumes for the MooreJohnson lease are shown on Figure 15C. The peak in production
from 1994 to 1998 reflects the addition of the Axem/Murfin MooreJohnson #3 and #4 wells. Annual production volumes for the entire
field are shown in Figure 15D. Total production for the field in 2002
was 45,000 BO. Since 1997, annual production volumes have
been declining at a rate of about 15% per year.
The field was unitized in 1995 for pressure maintenance by gas and
water re-injection. Effects of secondary recovery operations in the
north leases can be seen, beginning in 1998, in Figure 15B and for
the south lease in 1999 on Figure 15C.
Cumulative production for the field is shown on Figure 15E. The
year to date total production for the field is 1,729,000 BO. Average
per well production for the 19 wells in the field is 91,000 BO.
Average per well production for the eight Axem/Murfin wells is
93,750 BO.
150000
0
1991
Production for Moore-Johnson field is reported by the Kansas
Geological Survey (KGS). Cumulative production is reported by
lease and not individual wells. To attempt to show variation in
production in the individual wells, the lease production totals were
divided by the appropriate number of wells in each lease. Figure
15A illustrates the variation in production among all the wells. Note
the differences in cumulative production between the Witt “A” and
Bobcat leases in the north part of the field.
0
MO-JO 4
1990
Oil Production at Moore-Johnson Field
50000
MO-JO 3
MO-JO 2
ABEL #1
2003
100000
76.0
MO-JO 1
17
2001 2002
HUDDLESTON 34-11
87.0
< 10
2000
150000
76.0
87.0
10 - 20
1999
BO
BREWER 2
BREWER 1
1998
200000
WENDLEBURG 1-11
HUDDLESTON 33-11
20 - 30
YR
13.4
11
40 - 50
30 - 40
1997
32.4
25.5
BREWER 3
1996
1991
1992
1993
1994
1995
1996
1997
YR
1998
1999
2000
2001 2002
2003
The KGS reported seven wells still producing in 2003. Ultimate
recoverable reserves for the field will be about 2,000,000 BO
Page 18
Wallace
Gove
Logan
DETAILED SOIL GAS SURVEYS OVER A GAS TREND
BYERLY
Wichita
Scott
A large detailed regional soil gas survey was conducted by a major oil company in the
prolific Permian Chase Carbonate Gas Trend of the Hugoton Embayment of southwest
Kansas. As shown in Figure 16, the seven-foot soil gas survey covers an area of about
210 square miles and consists of 923 soil gas sites. The soil gas survey was sampled on
a box grid pattern with a one-half mile distance between samples. An average section
(640 acres) contains nine soil gas sample sites. Because the established well spacing
in this gas trend was 640-acres, this survey, based on sample density, would constitute
a detailed soil gas survey. It is noteworthy to mention, at this point, that the previously
discussed soil gas survey in the north part of the Morrow Sand Trend with 11 sites per
section was considered a reconnaissance survey because the unit spacing in that trend
for oil wells is 80-acres.
Lane
BR
AD
SHA
W
Greeley
Kearney
Stanton
Grant
Finney
PA N
OM
A
Hamilton
TON
Gray
KANSAS
GR
EEN
WO
OD
HU
GO
Haskell
Stevens
Morton
Seward
Meade
B. Location Map, Regional Soil Gas Survey
B1318
B1319
B1320
B1323
B1324
B1325
B1328
B1327
B1326
B1329
B1330
B1331
B0405
B0406
B0407
B0307
B0306
B0305
B0304
B0303
B0302
B1322
B1321
B1332
B0310
B0311
B0408
B0314
B0315
B0413
B0318
B0308
B0309
B0312
B0313
B0316
B0404
B0409
B0321
B0324
B0325
B0417
B0323
B0423
B0326
B0327
B0328
B0329
B0422
B0428
B0331
B0332
B0427
B0330
B0426
B0433
B0336
B0432
B0335
B0431
B0334
B0430
B0339
B0340
B0435
B0436
B0434
SS016B
SS026B
SS025B
SS036B
SS035B
SS046B
SS058B
B0300
SS071B
SS084B
B0301
B0678
B0684
B0698
B0728
B0746
B0758
B0772
B0721
B0722
B0729
B0730
B0731
B0737
B0747
B0748
B0760
B0761
B0762
B0763
B0764
B0759
B0773
B0775
B0776
B0777
B0778
B0774
B0738
B0750
B0749
B0751
B0752
SS089B
SS102B
SS112B
SS113B
SS152B
SS149B
SS150B
SS151B
SS156B
SS157B
SS158B
B0889
B0890
B0891
B0717
B0718
B0894
B0895
B0724
B0725
B0726
B0899
B0900
B0733
B0734
B0735
B0903
B0904
B0907
B0745
B0906
B0754
B0755
B0756
B0908
B0753
B0765
B0766
B0767
B0768
B0743
B0744
SS076B
SS088B
B0732
B0742
B0741
B0740
B0739
B0736
SS063B
SS101B
SS139B
B0716
SS054B
SS087B
B0723
B0715
B0714
B0720
SS042B
SS053B
SS100B
SS126B
B0710
SS030B
SS041B
SS099B
SS138B
B0703
SS029B
SS040B
SS086B
SS125B
B0697
SS006B
SS164B
SS165B
SS168B
SS169B
B0449
SS014B
SS013B
SS022B
SS023B
SS032B
SS033B
B0896
B0901
SS114B
SS127B
SS064B
SS065B
SS077B
SS078B
SS090B
SS103B
SS116B
SS115B
SS128B
SS129B
SS141B
SS142B
SS153B
SS154B
SS155B
SS159B
SS160B
SS161B
B0892
B0893
B0897
SS140B
SS091B
SS104B
SS117B
SS130B
SS143B
SS066B
SS067B
SS167B
SS166B
SS015B
SS170B
SS172B
SS171B
SS024B
SS174B
SS175B
SS034B
SS178B
SS179B
SS176B
SS045B
SS182B
SS183B
SS180B
SS177B
B0346
SS181B
B0347
SS184B
SS185B
B0349
B0350
SS044B
SS056B
SS057B
SS186B
SS069B
SS070B
SS189B
SS079B
SS080B
SS082B
SS083B
SS192B
SS193B
B0393
SS095B
SS197B
B0395
SS195B
SS196B
B0394
SS096B
SS092B
SS093B
SS105B
SS106B
SS118B
SS119B
SS200B
B0845
B0846
B0847
SS109B
SS199B
SS108B
B0856
B0857
B0858
SS081B
SS094B
SS107B
SS120B
SS121B
SS122B
SS131B
SS132B
SS133B
SS134B
SS135B
SS144B
SS145B
SS146B
SS147B
SS148B
SS198B
SS201B
SS190B
SS202B
SS188B
SS191B
SS194B
B0351
B0360
B0371
B0382
B0361
B0362
B0372
B0373
B0383
B0384
B0374
B0352
B0364
B0375
B0353
B0365
B0376
B0386
B0387
B0396
B0397
B0398
B0848
B0849
B0850
B0859
B0860
B0861
B0385
B0355
B0354
B0366
B0377
B0388
B0356
SS207B
SS205B
SS208B
B0232
B0243
B0244
B0367
B0368
B0378
B0379
B0390
B0357
B0358
B0255
B0369
B0370
B0266
B0381
B0380
B0211
B0219
B0214
B0227
B0226
B0215
Wichita
B0221
B0220
B0229
B0228
B0245
B0246
SS206B
B0867
SS209B
B0878
B0237
B0247
B0222
B0240
B0239
B0249
B0250
B0251
B0262
B0263
B0248
B0231
B0230
B0238
B0241
B0242
B0252
B0391
B0392
B0257
B0256
B0267
B0277
B0276
B0268
B0269
B0278
B0279
B0287
B0286
B0285
B0258
B0288
B0868
B0869
B0879
B0880
B0870
B0871
B0400
B0851
B0852
B0862
B0863
B0872
B0873
B0883
B0884
B0259
B0270
B0280
B0289
B0260
B0261
B0253
B0271
B0272
B0273
B0274
B0281
B0282
B0283
B0284
B0275
B0401
B0402
B0403
B0293
B0294
B0295
B0296
B0853
B0854
B0864
B0865
B0855
B0866
B0662
B0663
B0664
B0874
B0672
B0665
B0298
B0299
B0666
B0671
B0675
B0674
B0673
B0876
B0875
B0670
B0669
B0668
B0667
B0297
CARWO
B0677
B0881
B0882
B0254
B0265
B0292
B0291
B0290
B0264
B0389
B0399
B0877
SS204B
B0218
B0235
B0234
B0233
B0661
SS203B
B0213
B0348
SS055B
SS187B
B0225
B0224
B0212
SS173B
SS043B
SS068B
B0217
B0216
SS007B
B0359
SS031B
SS052B
SS098B
SS137B
B0696
SS021B
SS051B
SS075B
SS124B
B0702
SS020B
SS039B
SS062B
SS136B
B0709
SS005B
SS163B
B0223
SS012B
SS050B
SS074B
SS123B
B0708
SS019B
SS011B
SS038B
SS061B
SS110B
B0701
B0707
B0706
B0713
B0712
B0711
B0719
B0727
B0700
B0699
B0705
SS028B
SS027B
SS085B
SS111B
SS018B
SS017B
B0448
B0447
B0341
B0345
B0344
B0343
SS162B
SS003B
SS049B
SS073B
B0686
B0691
SS010B
SS037B
SS060B
B0682
B0690
B0695
B0694
B0693
B0692
B0704
SS048B
B0681
B0689
B0688
SS072B
SS002B
SS009B
SS004B
B0337
B0210
B0342
B0443
B0442
Logan
B0333
B0363
SS047B
B0685
B0680
B0683
B0687
SS097B
B0679
SS059B
SS001B
B0446
B0445
B0338
B0438
B0437
B0441
B0440
B0439
SS008B
B0421
B0425
B0429
B0444
B0416
B0420
B0424
UTHWEST
B0320
B0322
B0415
B0414
B0419
B0317
B0319
B0418
B0412
B0411
B0410
B0887
B0886
B0885
B0888
B0676
B0898
B0902
B0905
BYERLY EAST
B0757
B0828
B0825
B0830
B0835
B0840
B0826
B0831
B0836
B0841
B0450
B0451
B0469
B0470
B0488
B0489
B0506
B0832
B0833
B0838
B0842
B0843
B0452
B0471
B0490
B0507
B0522
B0536
B0550
B0783
B0834
B0837
B0798
B0812
B0811
B0844
B0786
B0785
B0784
B0797
B0839
B0771
B0770
B0769
B0829
B0827
B0453
B0454
B0455
B0456
B0472
B0473
B0474
B0475
B0492
B0493
B0494
B0799
B0800
B0813
B0814
B0787
B0788
B0791
B0792
B0804
B0806
B0802
B0803
B0805
B0801
B0816
B0817
B0818
B0819
B0815
B0458
B0457
B0476
B0460
B0459
B0790
B0789
B0463
B0462
B0461
B0478
B0479
B0480
B0481
B0482
B0477
B0496
B0497
B0498
B0499
B0500
B0501
B0780
B0779
B0793
B0807
B0794
B0808
B0781
B0782
B0795
B0796
B0809
B0810
B0820
B0821
B0822
B0823
B0824
B0464
B0465
B0466
B0467
B0468
B0483
B0484
B0485
B0486
BYERLY
B0487
B0505
B0491
B0508
B0509
B0523
B0524
B0537
B0495
B0512
B0511
B0510
B0526
B0525
B0538
B0513
B0514
B0515
B0529
B0530
B0527
B0543
B0542
B0541
B0540
B0502
B0516
B0517
B0518
B0519
B0531
B0532
B0533
B0534
B0544
B0545
B0546
B0547
B0548
B0558
B0559
B0503
B0520
B0504
LEOTI GAS AREA
B0521
B0535
B0549
B0539
B0551
B0552
B0563
B0564
B0574
B0575
B0584
B0585
B0553
B0554
B0565
B0566
B0576
B0577
B0586
B0587
B0555
B0567
B0578
B0579
B0580
B0570
B0581
B0560
B0561
B0571
B0572
B0573
B0582
B0583
B0592
B0591
B0600
B0601
B0602
B0603
B0610
B0611
B0612
B0613
B0595
B0596
B0597
B0605
B0606
B0607
B0608
B0616
B0617
B0618
B0609
B0619
B0628
B0629
B0620
B0621
B0622
B0623
B0630
B0631
B0632
B0633
B0625
B0626
B0641
B0636
B0637
B0638
B0640
B0635
B0639
B0634
B0645
B0647
B0648
B0649
B0651
B0644
B0646
B0650
B0643
B0659
B0660
B0652
B0653
B0627
B0654
B0655
B0656
B0657
B0658
B0562
B0593
B0590
B0599
B0594
B0624
B0569
B0589
B0604
B0615
B0557
B0568
B0588
B0598
B0614
B0556
LEOTI GAS AREA
B0642
LEOTI GA
1
0
1
2
3
4
5
6
7
8
9
10
KILOMETERS
1
0
1
2
3
4
5
MILES
5000
0
5000
10000
15000
20000
This detailed regional soil gas survey is located in Greeley and Wichita Counties, Kansas
to the west and north of Byerly (47.3 BCFG) and Bradshaw (334 BCFG) Gas Fields.
A portion of the soil gas survey was conducted over the northwest half of Byerly Field
for calibration purposes. The Permian Carbonate Gas Play (Chase and Council Grove
Groups) in the Hugoton Embayment is the most prolific and important hydrocarbon play in
this petroleum province. This area of SW Kansas is also referred to as the Hugoton gas
area. The major gas fields of this area – Hugoton, Panoma, Greenwood, Bradshaw, and
Byerly (Figure 16) have produced a total cumulative of 27 TCFG.
Byerly and Bradshaw Gas Fields, together, have a total cumulative production of 381
BCFG from the Chase Carbonate reservoir. Byerly Field was discovered in 1968.
Development drilling at Byerly Field (Figure 17) progressed rapidly through the 1970’s up
to 1985 when the field reached a maximum development of 55 wells. There was a hiatus
in development drilling from 1986 until 1990. Since 1990 there have been 14 Chase
Carbonate completions at Byerly Field. There are currently 46 producing gas wells in the
field of which 20% have been completed since 1995. Interpretation of the analytical data
from the soil gas survey within the northwest part of Byerly Field indicates that there are
some additional areas that can be recommended for further development drilling within
the field area.
The natural gas accumulations at Byerly Field are due to stratigraphic entrapment caused
by a facies change in the Permian Chase Carbonate reservoir where it grades from
limestones and dolomites in the east to nonmarine red beds in the west. The generalized
geology of the gas trend is illustrated in Figure 2. Regional dip of the Chase Carbonate
is to the east-southeast. The upper seal for the gas reservoirs are provided by anhydrites
and shales of the overlying Sumner Group. Average drill depths of the gas reservoir
at Byerly Field range from about 2750 to 2900 feet. Porosity and permeability in the
Chase Carbonate are highly variable as evidenced by the cumulative gas production from
individual wells as shown in Figure 17A. Cumulative gas production from wells in Byerly
Field range from 30 MMCFG to 3,572 MMCFG.
25000
FEET
B. Location Map, Regional Soil Gas Survey
Figure 16
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 19
The stratigraphic entrapment of the gas, relatively shallow
depth, and highly variable porosity and permeability of the
reservoir are factors which favor the application of surface
soil gas surveys as an important exploration method to
reduce risk in this play.
SS084B
B0301
322
B0678
58
773
564
832
442
116
1140 693
502
622
458
B0688
9
9
B0692
375
B0693
B0694
10
6
B0698
B0699
4
213
144
730
B0687
797
421
947
B0713
85
1644 1482
B0721
1741
421
B0740
504
730
66
2264 73
2773 1741 3572
249
B0751
695
865
527
1116
722 318
68
422
B0777
584
1669
457
223
B0805
30
534
CUMULATIVE GAS
PRODUCTION
PER WELL
B0819
0
1
SS139B
8
8
6
10
4
4
B0696
B0697
8
10
13
B0708
8
9
775
431
2
MILES
6
> 1,500
1,000 - 1,500
500 - 1,000
300 - 500
< 300
B0463
2
B0482
81
B0703
9
9
B0709
B0710
20
6
B0715
B0716
B0717
B0718
5
5
6
28
9
5
9
6
B0892
B0893
B0891
23
1
B0894
B0895
4
2
B0896
20
B0901
B0900
4
B0734
B0903
B0905
B0733
B0904
B0732
B0735
B0731
12
20
8
19
6
14
1
4
B0906
B0907
12
B0908
B0753
B0754
B0755
B0756
9
14
36
9
B0764
B0765
B0766
B0767
B0768
6
14
26
10
B0752
B0778
B0779
B0780
B0781
3
7
16
7
B0793
13
B0794
7
B0795
B0796
13
19
B0806
B0807
B0808
B0809
B0810
30
4
16
5
11
B0821
B0822
B0823
B0824
21
27
2
8
B0464
B0465
B0466
B0467
B0468
8
15
20
6
B0820
B0484
B0483
B0485
B0501
1
B0502
B0503
SS121B
4
4
SS133B
SS134B
18
20
SS144B
SS145B
SS146B
SS147B
93
11
9
4
B0519
B0520
SS122B
SS135B
SS198B
SS201B
SS204B
SS148B
SS207B
3
3
B0897
B0898
1
1
B0902
15
3
4
B0486
6
B0487
2
B0504
MILES
B0518
SS195B
16
B0782
B0792
8
4
SS120B
9
SS155B
4
SS107B
SS132B
5
12
40
SS108B
SS109B
118
SS154B
6
4
B0745
SS096B
SS131B
9
SS156B
B0899
18
SS095B
8
6
SS161B
12
B0744
SS094B
SS130B
SS153B
SS160B
B0890
9
10
SS159B
8
SS119B
SS143B
SS158B
SS106B
20
3
SS157B
SS105B
SS118B
SS142B
3
B0726
12
SS093B
11
4
5
22
B0743
SS092B
SS117B
SS141B
SS151B
B0889
SS104B
SS140B
7
B0725
34
67
SS150B
9
B0742
SS129B
130
6
B0724
12
SS128B
6
SS149B
5
B0741
SS127B
SS152B
B0723
B0722
SS091B
B0505
0
00
17
A. Contour Map of cumulative gas production from wells in northwest part of Byerly Field
B0702
B0714
20
MMCFG
51
6
35
6
326 2443
222
1
SS126B
11
SS138B
B0701
7
118
SS125B
16
SS137B
7
10
B0791
641
SS124B
5
B0707
91
1348
3
SS136B
5
24
B0763
SS116B
2
B0691
B0700
3
68
SS115B
4
B0690
138
B0730
SS114B
11
B0689
B0706
1
1123
SS113B
5
16
226 1171
B0705
SS112B
SS123B
B0695
SS103B
SS111B
10
16
SS102B
15
B0686
9
SS101B
SS100B
18
4
6
SS090B
SS099B
3
5
447
238
B0684
B0683
SS089B
10
SS098B
SS110B
SS088B
30
B0685
4
1099
B0682
B0681
B0680
SS097B
B0679
SS087B
SS086B
SS085B
ETHANE
CONCENTRATIONS
(ppb)
> 30
25 - 30
20 - 25
15 - 20
10 - 15
< 10
B0521
B. Ethane magnitude contour map in northwest part of Byerly Field
Figure 17
How to Design an Exploration Surface Soil Gas Geochemical Survey
The purpose of the regional detailed soil gas survey was
threefold: (1) calibration of the survey to the gas production
at Byerly Field, (2) to aid in possible further exploitation/
development drilling at Byerly Field, and (3) to determine
other areas along trend that exhibited similar anomalous
soil gas microseepage and would therefore indicate areas
of exploration potential.
The variability of the cumulative gas production from
individual wells in the northwest part of Byerly Field is
illustrated in Figure 17A. There is a pronounced northeastsouthwest orientation of porosity and permeability
development in the Chase Carbonate at Byerly Field. As
evidenced by the cumulative gas production contour map,
there are three porosity/permeability fairways at Byerly
Field. An ethane concentration contour map, constructed
from soil gas magnitude analytical data in northwest half of
Byerly Field, is shown in Figure 17B. There is very good
correlation between areas of maximum cumulative gas
production (Figure 17A) and anomalous ethane soil gas
concentrations (Figure 17B) in Byerly Field. The trends
of microseep anomalies, indicated by the contour map of
ethane magnitudes, exhibits the same northeast-southwest
orientations as seen in the contour map of cumulative
gas production. Since there are many more soil gas data
points than development wells at Byerly Field, the soil gas
anomalies, indicated by the contour map, probably provides
a more realistic depiction of the subsurface porosity/
permeability trends in the Chase Carbonate at Byerly Field.
A number of untested soil gas anomalies exist in the
remainder of the soil gas survey to the west and north of
Byerly Field. These anomalous gas microseeps are not
random, isolated points, but rather tend to cluster in groups
of gas microseep points that are on trend with established
Chase Carbonate gas production at Byerly and Bradshaw
Fields. These untested soil gas anomalies exhibit similar
soil gas magnitudes and areal extents as the soil gas
anomalies mapped within Byerly Field.
Page 20
090
090A
46
148
091
47
119
71
285
121
295
26
127
53
087
42
128
75
085
109
8
081
59
084
51
001
88
318
200
320
19
077
49
002
082113
36
005
217
003
124
319
76
11
092
36
076
215
069
65
WENDLEBURG 2-11
8
MILLER #1
067
48
KANSAS
BREWER 1
WENDLEBURG 1-11
12
11
BREWER 1
HUDDLESTON 34-11
BREWER 1
A
066
77
074
47
063
40
ABEL #1
13
14
18S41W
18S43W
18S41W
18S43W
095
MO-JO 4
MO-JO 2
073
52
76.0
MO-JO 1
17
MO-JO 3
094
22
130
73
HUDDLESTON 34-11
87.0
17
075
34
76.0
87.0
WILLIAM #1
LINN 1
LIMITS OF V7
INCISED
VALLEY-FILL
229
LINN 1
SELL #13-3
MO-JO 4
220
MO-JO 2
13
14
SELL 1
MO-JO 3
220
ABEL #1
LINN 1
12
11
BREWER 2
BREWER 2
070
30
WENDLEBURG 1-11
HUDDLESTON 33-11
HUDDLESTON 33-11
KELLER #2
13.4
32.4
25.5
BREWER 3
18S41W
18S43W
072
95
32.0
6.5
BREWER 1
BREWER 3
071
38
321
83
BREWER 2
KELLER #1
12
053
78
WENDLEBURG 2-11 WENDLEBURG 3-11
8
WENDLEBURG 3-11
BREWER 2
050
108
049A
83
203
Another major advantage of soil gas surveys is the relatively low cost. Considering sample
collection, laboratory analyses, and interpretation and reporting costs, the present day cost
of the 106 site soil gas survey conducted at Moore-Johnson field would be about $16,000.
This is only about 15% of the dry hole cost of a single Morrow well.
40.8
BREWER 24-2
BREWER 24-2
MO-JO 1
129
76
BLACKBIRD #1
14
SELL 1
13
SELL #13-3
061
57
0
1000
0
2000
1000
0
2000
ETHANE
CONCENTRATIONS
(ppb)
> 125
110 - 125
90 - 110
75 - 90
65 - 75
< 65
Limits and Dimensions of Morrow V7 Sands
Areal Extent
Width
Thickness
2000
BOBCAT LEASE
WITT "A" LEASE
V7d
0 - 30 ft.
1800 - 2700 ft.
WITT "B" LEASE
V7c
0 - 18 ft.
1300 - 2300 ft.
LANG LEASE
V7b
0 - 24 ft.
2300 - 3200 ft.
COYOTE
Morrow Well
Completion Zones
DRY HOLE LOCATED
IN AREAS OF
BACKGROUND ETHANE
MAGNITUDES
1000
Scale - Feet
Scale - Feet
Scale - Feet
LEGEND
CUM. BO x 1000
> 200
70 - 80
V7d
V7c
V7b
50 - 60
40 - 50
20 - 30
10 - 20
< 10
How to Design an Exploration Surface Soil Gas Geochemical Survey
In this portion of the Morrow trend, the sample density of 16 sites per section is only
adequate for defining a lead or prospect area and possibly acquiring acreage. This sample
density is not adequate for exploitation or development drilling. A sample density of at least
30 sites per section is needed as demonstrated at the Moore-Johnson field (LeBlanc and
Jones, 2004a).
Surface soil gas geochemistry will not eliminate all dry holes being drilled within a field. The
example previously discussed of the Bobcat #2-2 wells is a good example to illustrate this
point. As pointed out by Bowen and Weimer (2003), the V7 sands in this part of the Morrow
trend are of smaller areal extent, smaller in cross section, and more compartmentalized than
in the Morrow fields to the north. At the sample density of this survey, microseep anomaly
patterns could not distinguish the individual trends of the V7b, V7c, and V7d reservoirs.
This is because the widths only range from 1800 to 3000 feet (see legend, Figure 18B).
Perhaps a denser soil gas grid could have provided the necessary resolution.
Soil gas anomaly data can not distinguish between oil reservoirs of different geologic ages.
In this part of the Morrow trend, in most wells the Mississippian has been a secondary (or
primary) objective. Although not productive at Moore-Johnson field, anomalous microseeps
in the surrounding area could indicate Mississippian potential in addition to Morrow.
Additionally, shows were reported in some wells in the Pennsylvanian Lansing-Kansas City
interval.
80 - 90
30 - 40
Figure 18
As previously discussed, the major advantage of soil gas surveys in the Morrow oil trend is
that of risk reduction and potentially improving the success ratio. As shown on the Figure
18A, had the survey been available to all companies, then probably, 11 of the dry holes on
the west side and the north and south end of the field would not have been drilled. This
alone would have increased the overall success rate for the field from 56% to 82%. Had
the data been available to Amoco in 1990, at least five of the dry holes could have been
avoided, increasing Amoco’s success rate from 30% to 60%.
COYOTE 1
093
35
17
54.6
1.7
COYOTE 1
310
54
304
106
068
30
WITT B-1
BLACKBIRD #1
044
83
303
70
301
99
1
2
COYOTE 2
COYOTE 2
309
48
049
079
42
078
61
BOBCAT 1-2
83.3
43.3
WITT B-1
042
35
312
29
302
76
BOBCAT 2-2
1
2
LAWSON #1
BOBCAT 2-2
45.3
WITT A-2
65
046
103
051
96
WITT A-1
85.3
BOBCAT 1-2
WITT A-2
043
045
40
048
113
5
0.5
314
65
311
26
052A 052
77
115
080
97
083
88
316
47
AMOCO
LAWSON #1
BOBCAT 2-2
BOBCAT 2-2
1
047
58
115
115A
143
20
004
197
041
44
WITT A-1
292
59
313
36
294
197
118
101
317
75
300
80
040A
94
116
83
5
277
87
280
23
117
43
296
84
286
34
039
42
293
45
2
037
69
110
279
75
291
75
297
47
284
37
036
62
037A
038
62
089
71
A’
KANSAS
088
65
Advantages and Limitations of Soil Gas Surveys
LANG 34-35
LANG 34-35
276
161
278
50
COLORADO
121
58
281
135
272
123
273
124
230
76
COLORADO
5
229
42
282
63
283
41
KANSAS
124
41
COLORADO
228
39
There is no direct relationship between the magnitudes of microseeps and either the rate
or total volume of hydrocarbons a well will produce, except in a very general sense. This is
particularily true when comparing reservoirs having different entrapment mechanisms, such
as the Stateline Morro oil and W. Stockholm gas fields. However, as can be seen comparing
the ethane contour map (Figure 18A) to the production map on Figure 18C, this concept
may at least potentially work when comparisons are made over the same reservoir. For
example, the Bobcat lease (170,646 BO) has been more productive than the Witt “A” lease
(90,575 BO) and the Lang lease (477 BO). Similarly, the Coyote lease (95,362 BO) has
been more productive than the Witt “B” lease (1745 BO). The ethane magnitudes suggest
differences that may be related to these production volumes. This suggests that the amount
of reserves on a prospect could likely be improved by a company getting a competitive edge
in early lease acquisitions based on soil gas data. One of the reasons that Axem/Murfin had
such sizeable reserves at Moore-Johnson field was their excellent lease position.
Page 21
Colorado
Kansas
Smokey Hill
Sherman County
Wallace County
Recommendations
Lookout
Speaker
Cheyenne County
Bledsoe Ranch
Wildfire
Harker Ranch
"ST
Castle Peak
ATE
Sianna
LIN
66%
47%
Frontera
"
58%
ND
Sorrento Field
RE
ET
Arapahoe
Mt. Pearl
73%
49%
Mount Sunflower
68%
Arrowhead
Stockholm SW
Second Wind
Cheyenne County
42%
No Soil Gas
Jace
unty
41%
Sidney
56%
Kiowa County
Greeley County
30%
Moore-Johnson
Salt Lake/Haswell
90%
W/Soil Gas
0
McClave
mi
0
km
10
10
Figure 19
Factors Affecting the Rate of Return in the Morrow Trend
FACIES
TRACT
UPDIP
TRANSITIONAL
DOWNDIP
FIELD
RESERVOIRS
SUCCESS RATIO
YRS. TO
DEVELOP
AVG. PER WELL
RESERVES BO
Sorrento
V7
58%
10 YRS.
1979-1988
358,333
Mt. Pearl-Sianna
V7
47%
6 YRS.
1984-1990
321,429
Arapahoe
V3
V7
66%
3 YRS.
1988-1990
154,419
Frontera
V7
73%
3 YRS.
1988-1990
106,429
SW Stockholm
V7
68%
9 YRS.
1979-1988
69,892
Second Wind
V3
V7
54%
4 YRS.
1988-1991
139,474
Sunflower
V1
V3
V7
49%
4 YRS.
1993-1998
83,500
Sidney-Kriss
V1
V3
V7
41%
9 YRS.
1990-1999
42,950
Jace
V1
V7
31%
5 YRS.
1989-1993
63,846
V7
42%
W/O SOILGAS
SURVEY
90%
W/ SOIL GAS
SURVEY
2 YRS.
1992-1994
91,000
Moore-Johnson
Figure 19 and Table 2 list success rates for development drilling
in representative fields in the Morrow oil trend and other factors
(years to develop, per well reserves) affecting the rate of return in
the Morrow trend. The fields are grouped according to the facies
tracts as defined by Bowen and Weimer (2003). It is apparent that
the newer fields most recently developed (Jace, Sunflower, Sidney)
have the lowest success rates. As shown at Moore-Johnson field,
high-density soil gas surveys could improve drilling success in
these areas. Employment of soil gas surveys could also have
accelerated the development drilling schedule at Sorrento and SW
Stockholm fields from the 10-year period that was required for full
field development. As discussed by Bowen et al. (1993) initially
(1979 to 1984), an incorrect depositional model was the main
reason for the rather lengthy development time frame for these two
fields.
Success rates for Morrow exploration wells were reported by Bowen
et al. (1993) to have been 5% in the Sorrento-Mt. Pearl-Sianna area
and reported by Moriarty (1990) to have been 10% in the Stateline
area. There still remain areas of untested Morrow exploration
potential in the transitional and updip facies tracts where soil gas
surveys could be employed to improve the exploratory success
rates over those previously reported. Regional isopach maps of
the upper Morrow section have been used to define other areas
where Morrow V1, V3, and V7 incised valleys might exist (Bowen
and Weimer, 2003, Figure 10). Regional soil gas surveys could be
very useful in exploration ventures when used in conjunction with
this method, especially in areas with sparse well control (LeBlanc
and Jones, 2004a).
As shown in this paper, surface soil gas geochemistry has been
successfully used in developing oil reserves in the Morrow V7
incised valley trend. This method would also be applicable in other
Morrow incised valley trends of southeast Colorado and southwest
Kansas such as the V1 and V3 Valley systems. As reported by
Bowen and Weimer (1997, 2003) these two incised valley systems
are transparent on 2-D or 3-D seismic due to their close proximity
to the base of Atoka/top of Morrow interface. Additionally, other
Morrow incised valley fill systems were outlined by Wheeler et
al. (1990) in Wallace County, Kansas and farther south in Kiowa,
Brent, and Powers Counties, Colorado.
A high degree of compartmentalization has been observed in the
V7 reservoirs in the downdip facies tract. Future soil gas surveys in
this area, for development drilling purposes, should have a higher
density of samples than the grid of 30 sites per section used in
the 1992 survey at Moore-Johnson field. For regional exploration
activities in the Morrow trend, a soil gas grid of 16 sites per section
appears satisfactory only for delineating regional microseep
anomalies.
Soil gas geochemistry would also be applicable in other younger
Pennsylvanian incised valley systems that have been identified in
central and southern Kansas and northern Oklahoma (KGS, 2003).
Likewise, Cretaceous age incised valley-fill systems exist in Rocky
Mountain areas such as the Denver, Powder River, and Williston
basins. The generalized paleodrainage network for the Muddy
Formation was illustrated by Weimer (1992, Fig. 3) over the north
Colorado, Wyoming, and eastern Montana areas. A more detailed
picture of paleovalleys in the Denver basin which were filled with
Muddy valley-fill sandstones was also presented.
The advantages of using each of the disciplines of geology,
geophysics, and soil gas geochemistry in Morrow exploration and
development are well known, however the three disciplines have
seldom been used in tandem. A somewhat lesser discussed topic
is that of the limitations of these three sciences.
The limitations of using soil gas surveys in the Morrow oil trend
have been discussed, to some extent, in this paper. Bowen et
al. (1993) discussed limitations of subsurface geology and 2-D
seismic in locating reservoir quality sandstones in the Sorrento-Mt.
Pearl-Sianna area. Germinario et al. (1995) likewise discussed
the limitations of 2-D and 3-D seismic surveys in locating both the
incised valleys and reservoir sandstones in the southern Stateline
Trend.
The integrated, multidisciplined approach of using geology,
geophysics, and soil gas geochemistry in Morrow exploration
(LeBlanc and Jones, 2004b) is a superior method whereby the
advantages in one of the three disciplines complement and
overcome the limitations or shortcomings of another.
Table 2
How to Design an Exploration Surface Soil Gas Geochemical Survey
Page 22
Summary
A high-density soil gas survey was conducted in the vicinity of Moore-Johnson field in
1992. The survey was conducted after the discovery of the field and initial development
attempts, all by the same major oil company, which resulted in a total of 10 wells (3 oil
wells, 7 D&A). A second attempt to extend the field, starting in 1992, was conducted by
six independent oil companies. One of the companies used an integrated approach of
combining subsurface geology and seismic with a detailed geochemical soil gas survey.
The remainder of the companies used industry-standard Morrow exploration techniques
acquired from 1978 to 1990 during development of Morrow oil fields to the north.
A high-density soil gas survey, consisting of 106 sites, was conducted over a four square
mile area of interest. Integration of geochemistry, geology, and geophysics resulted in a
compatible, unified interpretation that the field could be extended to the north.
The company utilizing the soil gas survey completed the first well to extend the field with a
4700-foot stepout. This company completed eight consecutive successful Morrow wells in
the field before drilling a dry hole. After drilling 10 wells, the company had a 90% success
rate. A total of 34 wells were drilled to both define the limits of the field and develop the
Morrow reserves. By only drilling 29% of the total wells, the company utilizing soil gas
geochemistry acquired 47% of the reserves produced to date. Success rates for the
remainder of the other field operators were 0%, 30%, 50% and 67%
There are still areas of untested potential in the Morrow oil trend. Fields discovered to
date have produced 66.5 MMBO with ultimate recoverable reserves estimated at about
110 MMBO. Fields in the southern portion of the trend are in the downdip facies tract as
characterized by Bowen and Weimer (2003). The Morrow sands in these wider incised
valleys are of smaller areal extent, smaller in cross section, and more compartmentalized.
Correspondingly, the average reserves per well are smaller than the northern fields.
Although reserves are lower in the downdip facies, employing soil gas geochemistry can
improve the relatively low success rates now being encountered in this area. This could
vastly improve the rate of return.
This documentation of a successful application of a detailed soil gas survey demonstrates
how the method could be used to delineate other areas of Morrow incised valley-fill
systems in areas of untested potential. Additionally, the method would also be applicable
in incised valley-fill systems of other geologic ages in Midcontinent and Rocky Mountain
basins.
Soil gas geochemistry is not a panacea for Morrow exploration, exploitation, or development
drilling, but is an integral part of a thorough exploration program. Applying the recently
related concepts of Morrow sequence stratigraphy will undoubtedly be a tremendous
advantage in future Morrow exploration and development drilling ventures, reservoir
maintenance, and in secondary recovery operations. Using soil gas geochemistry in
tandem with this concept would provide a very powerful synergistic effect to Morrow
exploration and development projects.
How to Design an Exploration Surface Soil Gas Geochemical Survey
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Page 23