Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

CHAPTER 5.
GEOMECHANICAL SIMULATION OF CO 2 INJECTION
1z:100x:100y 1z:100x:5y 1z:5x:5y
Soft 9.33 × 10 −3 4.85 × 10 −4 1.60 × 10 −4
5.98 × 10 −3 7.12 × 10 −4 2.13 × 10 −4
Medium 1.28 × 10 −3 9.07 × 10 −5 4.85 × 10 −5
1.35 × 10 −3 1.84 × 10 −4 4.60 × 10 −5
Hard 2.40 × 10 −3 1.14 × 10 −4 5.47 × 10 −5
1.69 × 10 −3 1.89 × 10 −4 5.18 × 10 −5
Table 5.5: Maximum surface uplift normalised by the reservoir pore pressure change (m/MPa)
for each case. The values in blue are for the deep reservoirs, in red are for the shallow models.
5.6 Summary
• The use of fully coupled fluid-flow/geomechanical modelling is a recent development in the
hydrocarbon industry. As part of the IPEGG project a model linking commercial fluid flow and
geomechanical packages has been developed.
• I have modelled a suite of simple, cuboid reservoirs with varying geometry and material properties
in order to examine the controls on stress path evolution during injection.
• I find that smaller reservoirs with a reservoir that is softer than the overburden, are prone to
stress arching, where much of the load induced by injection is accommodated by the overburden.
In contrast, extensive reservoirs with stiff reservoirs in comparison to the overburden do not
transfer stress into the overburden.
• The potential for shear failure and microseismic activity is parameterised with a fracture potential
term that describes the evolution of differential stresses. I find that failure is most likely to
occur inside small, hard reservoirs, and above small soft reservoirs. Extensive reservoirs appear
to have a lower risk of inducing brittle, shear failure.
• An alternative method for monitoring CO 2 injection is to observe ground deformation using
satellites. I have shown how geomechanical models can be used to simulate ground deformation
to link InSAR observations with reservoir processes.
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