The Interplay of Geological Channels and Horizontal Wells in CO2 Plume Geothermal Production

CO2 plume geothermal (CPG) production has been studied intensively in the past 10 years and demonstrated an effective utilization approach of CO2 Capture Storage (CCS). Owing to its favorable thermodynamics, CO2 as a working fluid is more efficient than water-extracted geothermal harvest, particularly for low-enthalpy geothermal reservoirs, which are typical in North Oman oil fields. These fractured carbonate reservoirs are characterized by fault channels and fracture networks. The objective of this paper is to numerically evaluate CPG with horizontal injection and production wells in channeled thin carbonate reservoir formations. Two sets of channeled reservoirs, parallel and perpendicular to the horizontal well placement are generated by geostatistical modeling. Reservoir performance metrics, including lifespan, CO2 circulation and storage, total heat recovery are evaluated and compared between the two heterogeneous and the homogeneous scenarios. The results indicate that geologic channels parallel to flow direction could develop shortest preferential CO2 flow paths, causing bypass of the hot low-permeable zones, faster temperature decline and reduced total recovered heat energy in production wells. Channels perpendicular to the flow direction could create zigzag preferential paths, and the corresponding heat sweeping efficiency is comparable to the homogeneous formation. This finding suggests in channeled geothermal reservoir, horizontal wells should be placed in parallel to the channels.