Assessment of CO2 EOR and its geo-storage potential in mature oil reservoirs, Shengli Oilfield, China

Most oil reservoirs in the Shengli Oilfield area have entered middle and late development stages after nearly 40-years of production, and they are suitable for applying CO2 EOR and carbon storage techniques. This study is aimed at assessing the potential of CO2 EOR and storage in three large oil fields in the region based on the data of 183 mature oil reservoirs. The assessments include a regional geology assessment, storage site screening, reservoir screening for CO2 EOR and EOR potential and storage capacity calculations. Many mature oil reservoirs are close to the main CO2 sources and have good geographical and geological conditions for CO2 storage. Of 41 reservoirs, 18 are suitable both for EOR and storage while 23 reservoirs were found suitable for storage as depleted oil reservoirs. The total EOR potential could be 999.72×104 t and the CO2 storage potential could reach 9,553.92×104 t. The overall incremental oil recovery rate could be 5.76%. The greater OOIP the oil reservoir has, the greater potential for CO2 EOR and storage it will have, and the more suitable for large-scale storage projects it will be. Those oil reservoirs suitable for CO2 EOR with large OOIP will be the preferred sites for CO2 storage. Many nearly depleted oil reservoirs with large OOIP can be considered as main sites for CO2 storage in the near future.