Evaluation of CO2 enhanced oil recovery and CO2 storage potential in oil reservoirs of Bohai Bay Basin, China

The Bohai Bay Basin is the largest petroliferous sedimentary basin in China. This basin is encompassed by the Bohai Sea economic zone where a large volume of CO2 is emitted directly into the atmosphere without any treatment. Meanwhile, most of the oil and gas provinces in this basin are facing the selection of tertiary recovery technologies after the completion of water flooding. CO2 enhanced oil recovery (CO2-EOR) is an optimal choice for achieving both a reduction in CO2 emissions and enhanced (or improved) oil recovery. In this paper, an evaluation of the CO2-EOR and CO2 storage potential was carried out at the reservoir scale, based on an established oil reservoir database from numerous data sources, to provide the basis investigating CO2-EOR site selection and regional CO2 emission reduction in China. Moreover, an assessment scheme for the oil reservoirs in the Bohai Bay Basin was also proposed. The results showed that 613 CO2-EOR candidate oil reservoirs, including 354 miscible CO2-EOR candidate oil reservoirs and 259 immiscible CO2-EOR candidate oil reservoirs were identified by applying the screening methodology to 2,891 oil reservoirs in the Bohai Bay Basin. It was predicted that 683 Mt of additional oil can be produced from the CO2-EOR candidate oil reservoirs, and simultaneously 1,345 Mt of CO2 would be incidentally stored in these candidate oil reservoirs. Furthermore, the most prospective area is the miscible CO2-EOR candidate oil reservoirs in the Shengli oil and gas province, where 140 Mt oil could be produced with the CO2-EOR and the injection and incidental storage of 225 Mt of CO2.