Vol.119, No.4, 2022, pp.1681-1695, doi:10.32604/ee.2022.019843
OPEN ACCESS
ARTICLE
Study of CO2 Flooding to Improve Development Effect in Conglomerate Reservoirs
  • Haihai Dong1, Yaguang Qu2,3,*, Ming Liu4, Lei Zhang1, Jiakun Wu5
1 Research Institute of Exploration and Development, Petrochina Xinjiang Oilfield Company, Karamay, 834000, China
2 School of Petroleum Engineering, Yangtze University, Wuhan, 430100, China
3 Ministry of Education Key Laboratory of Oil & Gas Resources and Exploration Technology, Wuhan, 430100, China
4 Xinjiang Oilfield Company of CNPC, Karamay, 834000, China
5 Karamay Drilling Company of CNPC West Drilling Corporation, Karamay, 834000, China
* Corresponding Author: Yaguang Qu. Email:
Received 19 October 2021; Accepted 27 December 2021; Issue published 23 May 2022
Abstract
For low permeability sandstone reservoirs, CO2 flooding has been proved to be an effective method to enhance oil recovery. Reservoir A is a typical conglomerate reservoir in Xinjiang oilfield. The reservoir has strong water sensitivity, and the injection pressure continues to rise. Furthermore the oil well pressure continues to drop. According to the screening conditions of CO2 flooding, the reservoir A can easily achieve CO2 miscible flooding with moderate temperature. And the reservoir has the advantage of being close to the gas source. Firstly, the relationship curve between CO2 oil displacement efficiency and oil displacement pressure was obtained by changing the oil displacement pressure using the fine-tube experimental model, and the minimum miscible pressure of CO2 oil displacement was determined. The minimum miscible pressure of reservoir A was 24.1 MPa. The change of oil phase state after CO2 injection was further studied by CO2 gas expansion experiment. The results show that the saturation pressure of formation oil increases significantly after CO2 injection, and the more CO2 injection, the higher the saturation pressure of formation oil. When the CO2 content in the injected crude oil is 55.29 mol%, the saturation pressure of the CO2 formation crude oil system reaches 31.60 MPa. Then, in order to better simulate the real reservoir conditions of conglomerate reservoir, the 2D visualization model of the outcrop was processed to analyze the microscopic oil displacement mechanism of CO2. The experimental results show that the remaining oil after water flooding mainly exists in the form of cluster, film, column and blind end, and the remaining oil after gas flooding exists in the form of island, cluster and film, and there is an obvious gravity overlay phenomenon. CO2 flooding after water flooding significantly improved sweep efficiency and enhanced recovery. Finally, through the analysis of CO2 field injection effect in reservoir A, it is shown that CO2 absorption capacity of single well is significantly higher than water absorption capacity. The equilibrium degree of production profile in gas injection stage is better than that in water flooding stage. Injecting carbon dioxide quickly restores formation pressure. The oil recovery effect after gas injection in the trial production stage is obviously improved compared with that in the water flooding stage. The research results of this paper provide a reference for the field application of CO2 flooding enhanced oil recovery technology in Xinjiang conglomerate reservoir.
Keywords
CO2 flooding; physical simulation; miscible pressure; enhanced oil recovery
Cite This Article
Dong, H., Qu, Y., Liu, M., Zhang, L., Wu, J. (2022). Study of CO2 Flooding to Improve Development Effect in Conglomerate Reservoirs. Energy Engineering, 119(4), 1681–1695.
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