Dynamic validation of subsurface CO2 utilization and storage capacity in depleted gas carbonate reservoirs, northeastern Thailand

Abstract

To address Environmental, Social, and Governance (ESG) concern, regarding climate action, the Intersect IX numerical simulator was used to evaluate a potential for carbon dioxide (CO2) geological storage and Carbon Capture Utilization and Storage (CCUS) opportunities in the Sin Phu Horm gas field, northeastern Thailand.  The actual field dynamic data, comprising pressure and production records, were applied to narrow down the ranges of uncertainties on the original gas-in-place (OGIP) of the reservoir model via the history matching process. Permeability anisotropy, representing the natural fracture network, was incorporated to accommodate well-level pressure matching. The results reveal a smaller OGIP volume than previously estimated, which alter CO2 storage capacity. After the end of the simulated field life, the gas recovery factor from this reservoir is forecasted to be 81%, with reservoir pressure of 2.2 ppg. - considerable depletion level and CO2 storage potential. 
The simulated results, after 20 years of Carbon Capture and Storage (CCS) process, indicate that reservoir pressure rebounds from 780 to 1,010 psi, from 0.19 MtCO2 per year injection rate, leaving significant remaining spare capacity. Enhanced Gas Recovery (EGR) potential, CCUS, from CO2 injection could add 4 to 7 percent incremental recovery factor benefit to the field reserves while meeting a gas sales CO2 composition constraint. This integrated CCS-EGR study provides, as a pioneer case for a Thailand onshore gas field, a workflow to assess both storage security and commercial gas recovery, showing that CCUS is technically viable in a mature Thailand depleted gas fields.