CO2 injection as a mitigation measure for land subsidence

Subsidence is a known consequence of liquid or gas production from the subsurface. The mechanism by which porous rock deforms and compacts under the influence of a fluid pressure change is well understood. Any decrease in fluid pressure will result in a proportional increase of the (compressive) effective stress in the porous reservoir rock i.e. more of the overburden weight must now be borne by the grain-to-grain contacts of the geological material itself.

The rock skeleton will compact whereas the amount of compaction will be primarily related to the compressibility of the compacting layer. In the case of poorly consolidated reservoir rock and specific rock types such as chalk, reordering of grain particles and collapse of rock skeleton (i.e. pore collapse) may occur.