Empirical Analysis of Thermal Recovery Potential and Steamflood Screening Criteria for Heavy Oil Reservoirs in the Calabar Flank Sub-Basin, Cross River State

Heavy oil reservoirs in the Calabar Flank Sub-Basin of Cross River State contain significant in-place volumes, but their low-gravity crude characteristics constrain conventional cold production performance and suggest a potentially favourable screening match for thermal enhanced oil recovery. This study empirically analyses thermal recovery potential and applies steamflood screening criteria to heavy oil reservoirs in the Calabar Flank Sub-Basin. Reservoir parameter data compiled from three exploration and appraisal wells drilled in the sub-basin include net sand thickness, depth, permeability, porosity, initial oil saturation, crude oil viscosity at reservoir temperature, and average water saturation. The Farouq Ali and the NPC screening criteria for steamflooding were applied to the compiled dataset to rank reservoirs by thermal recovery suitability. Viscosity-temperature relationships for the heavy crude samples were characterised by laboratory rotational viscometry at temperatures from 30 to 150 degrees Celsius, confirming strong viscosity sensitivity with a viscosity reduction from 8,400 centipoise at 40 degrees Celsius to 85 centipoise at 150 degrees Celsius. CMG STARS reservoir simulator was used to evaluate steam injection performance for the highest-ranked reservoir candidate, with the steam injection model tuned using analogous thermal recovery field data from Midway Sunset, California as a validation reference. Simulation forecasts indicate an incremental recovery factor of 22 percent above cold production expectations after a ten-year steamflood. Keywords: thermal recovery, steamflood, heavy oil, Calabar Flank Sub-Basin, Cross River State.