Technology and practice of CO₂ capture and storage from Yanchang Petroleum

Through the innovative combination of CO₂ capture in the coal chemical industry and oil reservoir CO₂ storage, Yanchang Petroleum has realized multiple benefits such as clean utilization of coal, carbon emission reduction, and crude oil production increase, and explored a new path for low-carbon development of coal chemical industry. The whole process integration technology and field practice of carbon capture, utilization, and storage (CCUS) from Yanchang Petroleum are systematically presented. For CO₂ capture, the low-temperature methanol washing and low-cost CO₂ capture technology of the coal chemical industry has been formed. The CO₂ capture cost is 105 yuan/t, and the capture demonstration scale is300000t/a. For CO₂ storage, the storage site selection and potential evaluation methods are established. The evaluation results showed that the theoretical CO₂ storage capacity of the oilfield is 8.84×10⁸ t, and the suitable storage area is mainly distributed in the west of the oilfield. In addition, the evolution laws of CO₂ storage state across the time scale of storage are revealed. Under the water-gas alternation scenario, the proportions of CO₂ storage capacity for structure, residual, solubility and mineral trapping corresponding to 10 years and 100 years is 24.38%, 27.19%, 48.38%, and 0.05%; and 15.09%, 38.65%, 45.77% and 0.49%, respectively. Then the sealing evaluation methods of the caprocks are created. It is specified that the Chang 4+5 cap layer in the Huaziping CO₂ sequestration test area mainly belongs to type Ⅰ and type Ⅱ. Finally, a “Trinity” CO₂ safety monitoring system is established. The results of safety monitoring show that, there is no CO₂ geological leakage in the test area and the safety level of CO₂ storage is Ⅰ. The safe and effective storage capacity of CO₂ is 10.12×10⁴ t in the field application. The technology of CO₂ capture in the coal chemical industry and reservoir CO₂ storage has achieved good effects of carbon reduction and crude oil production increase in field practice.