Steam injection into a shallow fractured and faulted reservoir has the potential to change the stress profile of the subsurface in such a way as to induce microseismic events that could eventually reactivate faults and fractures, especially if steam injection temperature is significantly high and fracture spacing is small. A 3D mechanical earth model (MEM) of a thermal gas/oil gravity recovery process illustrates the potential for steam to facilitate drainage by reducing viscosity of the heated matrix oil, leading to compaction that might be offset by upward movement of the surface in response to high steam temperatures. In our extreme case, the upward movement at ground level could be as high as ∼26 cm over 35 years. High levels of vertical deformation are increasingly likely where faults extend to the surface. Understanding these processes is important to ensuring the safety of the facilities over extended production times in environments of this kind.

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