CARBON DIOXIDE GEOSEQUESTRATION: OPTIMUM GAS INJECTION TEMPERATURE REQUIRED FOR CAP ROCK GEOMECHANICAL INTEGRITY

Abstract

In the efforts to mitigate the unprecedented anthropogenic carbon dioxide presence in the atmosphere, the decision to store this greenhouse gas in geologic repositories has received global appreciation with assured technical and financial viability. The implication is that the injection temperature of flue gas in the potential geologic sites will be typically those encountered in combustion power plants. This, obviously has a geomechanical consequence considering the fact that heat transferred from the aquifer to the low permeability cap rock will cause excessive pore pressure build up due to poor pore pressure diffusion characteristics of these rocks. While these low permeability rocks are required to provide stratigraphic trapping mechanisms such excessive pore pressure build up can result in compromising the geomechanical integrity. This article has used heat transfer theories and geomechanical concepts to obtain steady state temperature distribution in cap rocks for temperatures ranging from 50 to 800 °C. In so doing, cap rock critical temperatures for tensile and shear failures have been established for a potential on-site gas injection into saline aquifers.