Geomechanical Factors AffectingGeological Storage of CO2 inDepleted Oil and Gas Reservoirs

摘要

A key to the success of long-term storage of CO2 in depletedoil or gas reservoirs is the hydraulic integrity of both thegeological formations that bound it, and the wellbores thatpenetrate it. The integrity of this 'bounding seal' system isaffected by various mechanical, chemical and thermal forcesthat act during initial exploration, development and oilproduction operations, during CO2 injection operations, andduring the subsequent CO2 storage phase. This paper providesa review of the geomechanical factors affecting the hydraulicintegrity of the bounding seals for a depleted oil or gasreservoir slated for use as a CO2 injection zone. Equations aregiven which are helpful for identifying the key parameters thatgovern these geomechanical factors, and further enable first-order estimates of the risks that they pose to bounding sealintegrity. The results of this review are compiled into a tablethat summarizes key geomechanics-related risks, the mechanisms associated with these risks, and approaches toassess and mitigate them. Where possible, examples are givenwhere these mechanisms have affected oil and gas fieldoperations.