Statoil CO2 storage experience:
20 years and 20 million tonnes
Andrew Cavanagh, Anne-Kari Furre, Anders Kiær, Aina Dahlø Janbu,
Bamshad Nazarian, Britta Paasch, Philip Ringrose | Statoil RDI
CO2GeoNet
10th
Anniversary Open Forum, 2015
Classification: Open
2015-05-12
Statoil storage projects
2008
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Classification: Open
2015-05-12
1996
2004
The pioneering CCS project, Sleipner
!  Main learning: CO2 storage is feasible
The World’s first commercial-scale offshore storage project
•  Driver: Norwegian carbon tax
•  Storage unit: 800-1000 m depth, 200 m thick, high permeability
•  More than 15 Mt CO2 have been injected
!  Challenges:
−  Role of internal shale layers on plume movement
−  Predicting CO2 flow properties
!  Take-aways:
−  CO2 plume can be monitored by seismic and gravimetric methods
−  Down-hole monitoring would improve models
3
Classification: Open
2015-05-12
The pioneering CCS project, Sleipner
!  Main learning: CO2 storage is feasible
CO2
Condensate
Injection point
Injector
(T. Torp, 2000)
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Classification: Open
2015-05-12
Producers
(A. Kiær, 2014)
Sleipner monitoring
Injected CO2 (Mt)
! Cost-effective geophysical portfolio design
14
Seismic surveying
12
Gravity surveying
10
Seafloor mapping
8
CSEM survey
6
4
2
0
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
Year
5
Classification: Open
2015-05-12
Sleipner model
! Understanding CO2 plume dynamics
6
Darcy flow method
Percolating flow method
(Singh et al., 2010)
(Cavanagh, 2013; Cavanagh & Haszeldine, 2014)
Classification: Open
2015-05-12
Sleipner model
! Plume calibration based on seismic
•  Darcy flow approach:
−  Viscous forces, reservoir simulation
−  Vertical equilibrium assumption (VE)
−  Poor match, strong pressure artifact
•  Percolating flow approach:
−  Capillary forces, basin modeling
−  Gravity assumption for migration (MGN)
−  Equally poor match, but is buoyancy closer?
•  We then allow the pressure to dissipate in the VE reservoir simulation,
and the plume redistributes to its buoyant equilibrium position. A much
better match to the footprint of the seismic observation is achieved.
7
Classification: Draft
2015-05-12
Sleipner model
460
! 2-phase black oil reservoir simulation
•  Calibrating for 2008 seismic footprint
based on pressure equilibrium
10
100
90
80
70
60
50
40
30
20
•  Simulation time in years: 15
710
•  Pressure field at the end of injection:
~ 460 to 710 kPa (65-100 psi) overpressure
~ 250 kPa (36 psi) drop over 3 km
X
8
Classification: Draft
2015-05-12
Sleipner model
! Flow modelling favours near-equilibrium interpretation
!
##
!
Dynamic#equilibrium##
!
!
!
!
1999#################2001#####2002#################2004#################2006#################2008#
!
The simulation results clearly indicate that the plume beneath
the caprock is gravity-dominated, and close to equilibrium at
every observation point (Cavanagh, Energy Procedia, 2013)
Reservoir simulations for CO2 storage may be susceptible to
significant pressure artefacts that distort the model outcome.
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Classification: Draft
2015-05-12
Testing the boundaries at In Salah
! Main learning: the role of geomechanics and monitoring
Storage limits in a challenging environment
•  Driver: Joint Venture for technology development with BP and Sonatrach
•  Storage unit: 1880 m depth, 20 m thick, low permeability
•  3.8 Mt CO2 injected from 2004 to 2011
!  Challenges:
−  Injectivity: low permeability formation limited injectivity and capacity
−  Geo-mechanics: integrating monitoring techniques and modelling
!  Take-aways:
−  Developed pioneering onshore monitoring portfolio
−  Inclusive research approach resulted in many peer-reviewed papers
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Classification: Open
2015-05-12
Testing the boundaries at In Salah
! Main learning: the role of geomechanics and monitoring
Map of surface uplift
May 2009
20mm uplift
Injection
unit
Modelled rock strain (section)
(Gemmer et al., 2012)
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Classification: Open
2015-05-12
In Salah geomechanics
Sketch of geological and fluid
effects around injection well
KB-502 (Ringrose et al. 2013)
Lower caprock
(Secondary Storage)
Elevated pressure in
reservoir volume
1km
Depth
Upper caprock
(Main Seal)
Carboniferous
Rock mechanical strain propagating to surface
Cretaceous
!  Simple linear elastics not sufficient to explain observations
!  Hydro-fractures and fracture flow observed
Primary Storage Unit
CO2 plume
~ 1 km
2km
12
Classification: Open
2015-05-12
In Salah geomechanics
! All hydro-fracture hypotheses reviewed by White et al. 2014 (PNAS)
4D seismic:
Time-delay feature
(reprocessed seismic)
Modelling:pressure:
Well-head
Example analytical
Monitoring
reservoirmodel
response
KB 502
Interpretation:
Most likely case
•  Fracture zone has
propagated 200-300 m
into the lower caprock
•  No loss of storage
integrity
13
Classification: Open
2015-05-12
Applying the knowledge to Snøhvit
!
Main learning: integrating geophysics and injectivity
The world’s first offshore CO2 transport pipeline
•  Driver: Regulator license-to-operate (& carbon tax)
•  Distance: field-to-onshore facility is 150 km
•  Storage unit: 2600 m depth
•  Over 3 Mt CO2 has been injected since 2008
!  Challenges:
−  Reservoir heterogeneity
−  Near-well flow limits
!  Take-aways:
−  Need for robust design of injection system in heterogeneous reservoirs
−  A good ‘Plan B’ is invaluable when reservoir uncertainties are large
14
Classification: Open
2015-05-12
Applying the knowledge to Snøhvit
!
Main learning: integrating geophysics and injectivity
CO2
Gas
LNG plant
(Melkøya)
Injection point
(Osdal et al., 2014)
15
Classification: Open
2015-05-12
Applying the knowledge to Snøhvit
!
Main learning: integrating geophysics and injectivity
Tubåen reservoir quality
Detailed mapping based on 3D seismic
CO2
Gas
16
Classification: Open
2015-05-12
LNG plant
(Melkøya)
Applying the knowledge to Snøhvit
! Response to pressure build-up in the Tubåen
•  CO2 injection into the Tubåen
CO2 Formation
injection
until April 2011 (1 Mt)
•  Injection then diverted into the Stø Fmn
following well intervention (1.9 Mt)
Main field segment with
gas producers
N
CO2 Injector
GLC
Stø
Nordmela
X
Tubåen
(Ji-Quan Shi et al., 2011)
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Classification: Open
2015-05-12
S
Lessons learned from the last 20 years
1.  Can injected CO2 be monitored cost-effectively?
•  Yes" No " Maybe "
2.  Do we have enough storage capacity?
•  Yes" No " Maybe "
3.  Are we technically ready for very large projects?
•  Yes" No " Maybe "
4.  Is CO2 storage safe?
•  Yes" No " Maybe "
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Classification: Open
2015-05-12
Thanks to…
Anne-Kari Furre
Anders Kiær
Aina Dahlø Janbu
Bamshad Nazarian
Britta Paasch
Philip Ringrose
Statoil CO2 storage experience:
20 years and 20 million tonnes
Dr A J Cavanagh
Principal Researcher
RDI, CO2 Storage and EOR
[email protected]
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Classification: Open
2015-05-12