A New Class of Renewable Surfactants for Chemical Enhanced Oil
Recovery
Hadi ShamsiJazeyi*, Anton Kaiser*, Jonathan J. Wylde, Amir Mahmoudkhani,
and Dirk Leinweber, Clariant Oil Services
Abstract
With the ever-growing demand for more environmentally acceptable oilfield chemicals,
classic oilfield chemistries are becoming obsolete and new chemical systems are required.
Future oil production will be dominated by unconventional oil production with increased
amounts of chemicals needed to further improve oil recovery with higher production rates. In
addition, environmentally acceptable chemistries will be of increased significance and the use
of natural product based chemicals will further ensure a more sustainable oil production.
To achieve the future requirements of environmentally acceptable surfactants for chemical
enhanced oil recovery, chemistries with low toxicity and high biodegradability are needed.
Renewable based fatty acid amides represent such a class of bio-based surfactants that are
environmentally acceptable and show superior performance in enhanced oil recovery
applications.
The following paper describes the chemical design of renewable based fatty acid amide
surfactants and their use in EOR applications. Extensive phase behavior studies, salinity
scans, IFT measurements and surface tension measurements were performed to present the
high efficiency and potential of these products for alkaline surfactant polymer-, alkaline
surfactant- and surfactant flooding on different crude oils. Furthermore, the biodegradation
and aqua-toxicity of the renewable based fatty acid amide surfactants will be discussed in
detail. This new class of bio-based surfactants represents an environmentally acceptable
option to the broadly used internal olefin sulfonates with superior performance. The non-ionic
character of the renewable based fatty acid amide molecule results in much less ability to
adsorb on rock surfaces which allows a potential re-injection of the produced water to
decrease chemical consumption. Additionally, the viscoelastic behavior of this new class of
surfactants will improve the sweep efficiency during a flooding process. Overall, these multifunctional natural-based surfactants will drastically increase oil recovery rates when applied.
Keywords: Biodegradability, Enhanced Oil Recovery, Environment, Renewable, Surfactant
Introduction
There is an increasing worldwide demand for crude oil with only short-lived
fluctuations caused, typically by historical oversupply [1]. This means the production of crude
oil needs to increase at a similar pace in order to meet the energy demands around the globe.
One way to increase production is to change to higher efficiency oil and gas production
technologies. Such methods should be able to recover a greater percentage of the STOOIP
(Stock Tank Oil Originally in Place) in an economically viable way.
Enhanced Oil Recovery (EOR) is a common name for a series of technologies that can
significantly increase the production of oil and gas from a given reservoir. EOR is also known
as tertiary oil recovery due to the fact that it is usually done after primary step (recovery of oil
due to the natural pressure of the reservoir) and second step (flooding the reservoir with
water) [2].
Chemical EOR (CEOR) is a name given to a series of methods involving surfactants,
polymers, and sometimes alkaline substances in order to increase the oil production [2].
CEOR is a very promising technique that has repeatedly shown the ability to recover almost
all the STOOIP both in lab and field trials.
However, there are challenges ahead of widespread application of CEOR, the most
important of which are cost of chemicals and environmental aspects of chemicals [3, 4, 5].
The use of environmental-acceptable chemicals in CEOR applications can promote the
application of these methods, because increased production will not lead to any additional
chemical induced risk to the environment.
In the past few decades, there has been some effort to design biodegradable surfactants
from natural sources. One of the earliest cases is a patent published in 1992 that discloses
processes for making surfactants from fatty acids or their derivatives in combination with Nalkylglucamines, the latter made by reductive amination of glucose with methylamine [6].
Later, the surface properties of such fatty acid amide surfactants was studied [7, 8]. Also,
application of surfactants from natural sources have been studied in many different areas [912].
In this paper, application of a new class of surfactants for CEOR is introduced. These
fatty acid amide surfactants are mostly synthesized using abundant natural resources, are
biodegradable, lower interfacial tension, and show low adsorption to reservoir rock surfaces.
This class of fatty acid amide surfactants can be considered as a breakthrough in
environmentally friendly application of CEOR for increase in crude oil recovery.
Materials and Methods
Eagle-Ford condensate oil was used as oil phase to determine interfacial properties of
the surfactant. Silica and Kaolinite were provided by Evonik and Sigma-Aldrich, respectively.
Iceland Spar (by Ward Scientific) was crushed and powdered and grain size <40 micron was
used as a substrate for adsorption experiments, which will be referred to as Powdered Iceland
Spar.
The salinity scan tests were done by changing the concentration of NaCl in each
sample, while the concentration of fatty acid amide and C-20/24 IOS (internal olefin
sulfonate) was kept constant. For each sample, the final concentration of fatty acid amide and
C-20/24 IOS was 0.5 wt% per initial aqueous phase. 20 g of aqueous solution was contacted
with 5 g of condensate oil, which resulted in W/O weight ratio of 4:1. The phase behavior
experiments were done at a constant reservoir temperature of 60°C. The pictures were also
taken in a constant temperature oven fixed at 60°C.
The interfacial tensions were calculated based on Chun Huh relation [13] and the
observations from the phase behavior experiment on the amount of oil and water that was
solubilized in the micro-emulsion phase. Therefore, the interfacial tension values reported
were an approximation of actual values, valid for 60°C. If three phases were formed after
equilibrium, the interfacial tension between the micro-emulsion and oil was reported since
that is what matters most in oil recovery.
The surface tension measurements were done using a pendent drop method
tensiometer at room temperature in different salinities. 0.5 wt% of fatty acid amide was used
for these measurements in the absence of any other surfactant.
In order to measure surfactant adsorption on different minerals, accurate concentration
measurement is essential. The difference between the concentration of surfactant before and
after contacting the mineral (silica, kaolinite, or powdered Iceland spar) is related to the
adsorption of surfactant if precipitation is prohibited. The concentration of fatty acid amide
was measured using High Performance Liquid Chromatography (HPLC) with a Gel
Permeation Column (GPC). The calibration curve was measured between 0.4 to 1.0 wt%
concentrations. The initial concentration of fatty acid amide before contacting different
minerals was 1 wt%.
Results and Discussions
The experiments in this paper are designed to investigate the interfacial properties,
biodegradation, and aqua-toxicity of the fatty acid amide surfactant. The interfacial properties
are meant to study the feasibility of using fatty acid amide surfactants in CEOR applications.
In addition, studying the biodegradation and aqua-toxicity of the fatty acid amide assures us
about the environmental impacts of using this surfactant for CEOR applications.
Figure 1 shows the salinity scan experiment with fatty acid amide (0.5 wt% C-20/24
IOS is added) in the presence of Eagle Ford condensate oil at 60°C. Micro-emulsion middle
phase is seen in a wide range of salinities (5 to 8 % NaCl) using this surfactant system.
Observance of a micro-emulsion middle phase (Winsor type III) in this figure is a strong
indication of feasibility of using this surfactant for CEOR. This also can be seen as an
indication of ultra-low interfacial tension made by using this surfactant system. The ultra-low
interfacial tension is a necessary aim that a surfactant needs to provide to increase the
capillary number and in order for a CEOR project to be successful.
2
3
4
5
6
7
8
9
% NaCl
Figure 1) Salinity scan for 0.5 wt% fatty acid amide and 0.5 wt% C-20/24 IOS at 60°C.
Three different phases are observed as Winsor type I, III, and II, which are shown with
the red box in the picture.
The interfacial properties of a surfactant are very important in its application for
CEOR. An ultra-low interfacial tension is one of the most important properties that assure a
successful CEOR project. If a surfactant leads to ultra-low interfacial tension between oil and
water, this means that capillary force cannot maintain the oil inside the pores of the rocks as
long as such low interfacial tension is maintained. A low surface tension, resulted from using
surfactant, can also be important in many different types of EOR, including WAG, SAGD,
etc.
Table 1 contains more information about the interfacial properties of the fatty acid
amide. The interfacial tension between the 0.5 wt% fatty acid amide and 0.5 wt% aqueous
solutions of C20/24 IOS and Eagle Ford condensate oil has been calculated based on ChunHuh relationship. The surface tension measurements are reported for 0.5 wt% of fatty acid
amide and air at room temperature.
Based on the data provided in Table 1, it can be observed that the fatty acid amide has
very distinct interfacial and surface properties. The ultra-low interfacial tension and low
surface tension resulting from the use of the fatty acid amide promise great potential for its
use in CEOR applications.
In addition to the interfacial and surface properties of a surfactant, another factor in its
economic use for CEOR project is the adsorption on the rocks. If a surfactant highly adsorbs
on the reservoir rock, a great portion of it will be lost without contributing to the recovery of
oil.
Figure 2 shows the adsorption measurement for the fatty acid amide on silica,
Kaolinite, and Iceland Spar at different conditions.
Table 1) the interfacial properties of the fatty acid amide.
NaCl
Interfacial Tension
Salinity Without Surfactant
(wt %)
(mN/m)
2
41.31±0.32
5
43.12±0.49
10
46.29±0.52
kaolinite
Powdered Iceland Spar
a)
9
14
8
12
7
6
5
4
3
Surface Tension
Surface Tension
Without
With
Surfactant (mN/m) Surfactant(mN/m)
72.10±0.04
25.90±0.12
73.58±0.08
26.06±0.08
73.22±0.09
26.26±0.09
silica
Adsorption (mg/g)
Adsorption (mg/g)
silica
10
Interfacial Tension
With
Surfactant (mN/m)
12.51
0.0053
7.34
kaolinite
Powdered Iceland Spar
b)
10
8
6
4
2
2
1
0
0
0
20
40
60
Temperature (C)
80
100
0
2
4
6
8
10
NaCl Salinity (%NaCl)
Figure 2) Adsorption of fatty acid amide as a function of temperature and salinity on
different rocks/minerals.
As it was explained before, it is important to use environmentally-acceptable
chemicals for increasing oil and gas production, especially in CEOR. Figure 3 and Table 2
represent data on bio-degradation and aqua-toxicity of fatty acid amide. It can be seen in
Figure 3 that the fatty acid amide shows a continuously increasing marine bio-degradation and
would biodegrade totally with time in an marine environment.
Table 2 provides the algae EC50 aqua-toxicity data of the fatty acid amide surfactant. It
is reported that about 335 mg/l represents the EC50 value of the fatty acid amide, consequently
the fatty acid amide is not consider as aqua-toxic at all.
Figure 3) OECD 306 biodegradation of the fatty acid amide.
OECD 306 Biodegradation
60
50
40
30
Fatty acid amide
20
10
0
(%)
(%)
(%)
(%)
Day 7
Day 14
Day 21
Day 28
Table 2) Aquatic toxicity of the fatty acid amide.
Aquatic Toxicity
Test
Result (mg/l)
Fatty Acid Amide
72 hr Algae EC50
335.40
Conclusions
In this work, the potential application of a renewable surfactant (fatty acid amide)
from natural sources for enhanced oil recovery is studied. The surfactant shows a clear microemulsion phase in a salinity range, which indicates its potential to help increase the recovery
of oil from depleted reservoirs. The ultra-low interfacial tension was calculated based on the
formation of clear micro-emulsion middle phase. The surface tension of the surfactant was
also measured in different salinities.
In addition to the interfacial properties, the adsorption of this surfactant on silica,
kaolinite, and Iceland spar at different conditions was studied. These minerals represent some
of the common reservoir rock surfaces in the oil fields. The effect of salinity and temperature
on adsorption was measured. Overall, the adsorption of the fatty acid amide on these mineral
surfaces is extraordinary low, which makes its potential use for oil recovery applications
economical.
Finally, the data for marine biodegradability and aqua-toxicity of the Glucamide is
presented.
All in all, the fatty acid amide is an example for a class of surfactants that not only can
help recover more oil, but also do not harm the environment due to their ultralow aquatoxicity and high biodegradability.
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