1. Predicting the fate of CO2 in
geological reservoirs.
Mike Bickle,
(Earth Sciences & DAMPT,
Cambridge)
Nelly Assayag, John Becker,
Fran Boait, Hazel Chapman, Andy
Chawick, Benoit Dubacq, Herbert
Huppert, Niko Kampman, Sarah Lyle,
Alex Maskell, Jerome Neufeld, Nicky
White, Max Wigley, Andy Woods
&
the CRIUS Consortium
(Cambridge, Manchester, Leeds,
British Geological Survey)

2. What actually happens?
What have we learnt?
How should we go about learning more?
Geological analogues - Long time frames
- Demonstrate long-term
safety
Modelling – calculations - Numerical
- Analytical (physics)
- Laboratory tank
Field tests - Remote imaging
(small scale, full scale) - Downhole logging
- Sampling fluids

5. Crystal
Geyser
CO2
Reservoir
penetrated
by
exploration
well

6. Bleached sandstones: Possible fossil CO2-rich brines?
Use as analogue sandstones – fossil CO2 reservoirs?
Bleached for processes in CO2 storage reservoirs

7. Isopach Sleipner – separated from natural gas on
map of platform,
the Re-injecting CO2 at 1 million tons/year:
Utsira Started in 1996,
sand. Monitored by 3D seismic surveys in 1999,
2001, 2002, 2004, 2006 & 2008.

8. 1994 (injection started 1996) 1999 1999
Why model:
enable predictions – need to verify,
test assumptions and inputs.

9. seismic
imaging
~ 33 m
resolution
not < 8 m

11. Axisymmetric
Modelling ignores flow of
saline fluid velocity u, constant with
depth.
Lyle et al., 2005, J. Fluid. Mech.

14. Tank experiments

15. Tank experiments: normalised radius

16. Profile just stretches

24. Tank experiments: Waterton 4th yr project 2012

26. CO2 dissolution and fluid-mineral reactions:
An experiment on an Enhanced Oil Recovery phase.
Salt Creek: 3He & 129Xe spike injection 2010

27. Shallow Low Temperatures Challenges
•Unable to attain MMP conditions under conventional operations
•Low CO2 Density and Reduced Flood Front Velocity Promotes
Gravity Override
•Low CO2 Viscosity Magnifies Volumetric Sweep Challenge
1
2 1 Injection Pressure Limit
Water/CO2 Oil 2 CO2 Override
3
3 Unfavorable Mobility Ratio
How do we design a flood to best address these challenges?

28. Injection Experiment at
an Oil Field using CO2 for
enhanced oil recovery
Field has long and
complex history of water
injection for oil recovery
Progressive injection of
CO2 and re-injection of
produced water
Injection started here April 2008
Formation dips ~ 7° east
Seismic reflection images:
O’Brian et al., 2010, The Leading Edge

30. Dear diary,
Today the weather was nice and
warm but quite windy. We have
sampled 30 28 16 18 14 and filtered
and titrated everything. Filtering
and titrating is great fun and not
boring at all. I wish I could do that
all the time, and when I grow up I
want to be a chemist.

31. Water samples
-Separating oil

32. Water Chemistry: Mineral dissolution
Complex
history of
water
flooding,
injection of
water prior
to injection
of CO2

33. Well 18
Open symbols –
injection water
Note CO2 front ( 32 days) earlier
than anion fronts or d18O front
Injection waters arrive between
50 & 80 days?

34. Calculate fluid-mineral reactions from change in water chemistry
Plagioclase dissolution rate: ~ 5x10-14 mol/m2/s

35. Calculated reaction path: Calcite or Calcite + Plagioclase + Kspar – Sm - Qtz
CO2 solubility at 80 bars ~ 1.2 mole/L
Alkalinity at surface ~ 0.1 mole/L
Implies degassing in production well

36. Diffusion distance for CO2 into brine in 150 days is about 30 cm:
Can enough CO2 dissolve?

37. Sandstones: heterogeneous
and reactive

38. What is permeability structure of reservoir?
Wall Creek II On what scale does CO2 finger?
Flow of pure CO2 – 200 mD, 200 m, DP = 7 MPa
200 m in 4 days
Flow of CO2 displacing water:
200 m in 25 days

39. Model CO2 – brine movement with simple 1D model –Ask:
1) What is age and age distribution of water?
2) How much CO2 dissolves from CO2 adjacent to brine?
3) What is average CO2 content of produced water?
Model flow 1D, constant pressure differential, injected fluid viscosity 1/10th, sharp interface,
ignore cross-layer flow!

40. CO2 Flux?

41. Water ages – young, waters mixed

42. Conclusions:
1) Need to know flow paths to model CO2 dissolution
rates.
2) Need to know mineral reaction rates – especially
carbonate dissolution in field settings:
3) Carbonate dissolution may increase permeabilities
significantly.
Would be good to learn more about flow of CO2.
Fluid-fluid and mineral fluid reactions are surprisingly fast.
Need field injection experiments to understand controlling
small scale processes.