Cleaner coal and greener oil production: An integrated CCUS approach in Yanchang Petroleum Group

Abstract The Ordos Basin has the richest natural resources in China. It has over one third of the coal resources of China and it is the second largest oil and natural gas sedimentary basin in China. The Yanchang Petroleum Group is the only company that has both coal and petroleum mineral rights in this basin, which provides a unique favorable condition for implementing a carbon capture utilization and storage (CCUS) project in China. The CCUS project conducted by the Yanchang Petroleum Group integrates a clean coal chemical plant with low-cost carbon dioxide (CO 2 ) capture facilities and CO 2 enhanced oil recovery (EOR) and storage in tight formations. The coal chemical plant produces methanol and acetic acid from coal using the Texaco coal gasification process. High purity CO 2 is separated from the methanol rich solvent. After compression and deep-freezing treatment, liquid CO 2 with a purity of 99% is produced for CO 2 EOR and the storage project. The cost of the CO 2 product is about 117 Renminbi (RMB)/tonne CO 2 , which is less than US $18/tonne of CO 2 . This cost is about half of the cost of CO 2 in the coal power plant (US $30-40/tonne). The captured CO 2 is transported to a CO 2 EOR and storage project about 30–100 km away, which is a much shorter distance than the required transportation distances of other commercial CO 2 EOR and storage projects. For example, the transportation distance is over 300 km for the Weyburn project. The short distances between the CO 2 capture facility and the oil fields further reduce the transportation costs of the CCUS project in China. The oil fields in the Ordos Basin are mainly tight formations with low reservoir pressures. Water resources are very limited in the basin. Thus, minimizing water usage in the petroleum industry can significantly protect the environment in this area. Carbon dioxide EOR can reduce the water usage and enhance oil recovery at the same time. An extensive experimental study was conducted to maximize the performance of CO 2 EOR in tight formations with low reservoir pressures. The current reservoir pressure in those oil fields is less than 10 MPa, which is far lower than the minimum miscible pressure (MMP) (16–22 MPa). Different approaches, such as CO 2 foam flooding and huff-n-puff, have been proposed to build up the reservoir pressure to enhance the oil recovery performance. A field pilot test, containing about 50 wells, has been conducted for four years, and the oil production rates for those wells have been doubled or tripled. This project is the first integrated CCUS project operated in China. Currently seventy thousand tonnes of CO 2 have been injected. In the next five years, this project will be expanded to 1 million tonnes of CO 2 injection, which will make it the second largest CCUS project in the world after Canada’s Weyburn project.