Geomechanical aspects of CO2 sequestration in a deep saline reservoir in the Ohio River Valley region

Abstract

The Ohio River Valley CO2 Storage Project is an ongoing characterization of deep saline formations being considered as potential sites for geological CO2 sequestration. We completed a geomechanical analysis of the Rose Run Sandstone, a potential injection zone, and its adjacent formations at the American Electric Power's 1.3-GW Mountaineer Power Plant in New Haven, West Virginia. The results of this analysis were then applied to three investigations used to evaluate the feasibility of anthropogenic CO2 sequestration in the potential injection zone. First, we incorporated the results of the geomechanical analysis with a geostatistical aquifer model in CO2 injection-flow simulations to test the effects of introducing a hydraulic fracture to increase injectivity. We observed a nearly fourfold increase of injection rate caused by the introduction of a hydraulic fracture in the injection zone. The flow simulations predict that a single vertical well with a hydraulic fracture could inject a maximum of 300–400 kt of CO2/yr. In the second investigation, we determined that horizontal injection wells at the Mountaineer site are feasible because the high rock strength ensures that such wells would be stable in the local stress state. The third investigation used the geomechanical analysis results to evaluate the potential for injection-induced seismicity. If preexisting, but undetected, nearly vertical faults striking north-northeast or east-northeast are present, the increased pore pressure from CO2 injection would raise their reactivation potential. Geomechanical analysis of potential CO2 sequestration sites provides critical information required to evaluate its sequestration potential and associated risks.