CO2-EOR in China: A comparative review

Given China's economic dependence on coal for energy and industry, carbon capture, utilization and storage (CCUS) technology is a critical decarbonization strategy. Carbon dioxide (CO2) enhanced oil recovery (EOR) is critical to success of CCUS in China, providing the industrial know-how for long-term carbon storage. Carbon dioxide flooding in both China and the United States began in the 1960s. While the United States produces about 300,000 barrels of EOR oil per day, China's EOR efforts still face significant hurdles. This paper presents a compilation and brief review of CO2-EOR data, some of it previously unpublished, from the three major Chinese oil companies (China National Petroleum Corporation, Sinopec, and Yanchang Petroleum Company) and one private company (Dunhua) that presently maintain pilot CO2-EOR floods. The authors have visited several of the projects discussed in the paper and some observations from these visits are included. China's EOR projects generally produce from deep, tight, largely continental clastic reservoirs requiring hydraulic fracturing to create flow paths. There are no separation and recycle facilities-necessary to contain CO2 in the system- and there are presently no supercritical pipelines for CO2 supply. Several CO2-EOR projects have established monitoring and storage pilot projects but the absence of recycle means determination of net storage is not possible. China's projects could benefit from improved reservoir selection, new CO2 monitoring tools and operating strategies, expanded front-end investments in CO2 infrastructure such as pipelines and modern surface separation and recycling facilities that will serve to reutilize and store CO2.