Maximizing CO2-EOR Potential for Carbonate Reservoir, Horus Field, Western Desert, Egypt

Horus field whose main reservoir is Abu Roash "G" Dolomite, has been facing a declination in the production rates; however, it has managed to maintain a stable oil production plateau of 1050 barrels per day, with a significant water cut of 65%. This paper aims to investigate the efficiency of CO2 EOR for Horus field to identify the optimal approaches for maximizing the oil recovery. An experimental study was employed using a real core plugs samples from the field. The setup was configured to mimic the reservoir conditions at 70°C and 1200 psi, followed by injecting formation water, crude oil, and CO2 to study primary drainage, secondary imbibition, and enhanced oil recovery (EOR). The study yielded results of achieving 0.59 PV oil saturation after primary drainage and further oil recovery through subsequent water flooding and CO2 injection. The findings presented a promising opportunity into the behaviour of the CO2 in the carbonate reservoirs and its impact on the oil recovery where the Primary recovery methods produced 11.5 million barrels, representing a recovery factor of 19.6% of the OOIP. While water flooding increased the recovery factor to 23.7%, resulting in an estimated cumulative oil production of 14 million barrels. The increase in oil production from primary recovery to water flooding was 2.5 million barrels, representing a 21.7% improvement over the primary recovery production. However, CO2-EOR achieved a significant increase, with cumulative production reaching 22 million barrels and a recovery factor of 37.3%.