关键词: CO₂驱, 全域驱替, 多域耦合, 最小混相压力, 注采调控, 提高采收率

Abstract:

The Xinjiang oilfield faces the challenges such as complex reservoir type, strong reservoir heterogeneity, and low recovery efficiency. Considering the requirements for petroleum industry to meet China’s “dual carbon” goals, and through literature review, laboratory experiments, integration of key technologies, and field application in typical reservoirs, this paper proposes a theory of full-domain CO₂ flooding to effectively guide the significant enhancement of oil recovery through CO₂ flooding in highly heterogeneous reservoirs. A coupling mechanism between displacing medium (CO₂) and reservoir characteristics across three dimensions (space domain, time domain, and fluid domain) is established to maximize the mobilization of crude oil in pores and throats of varying scales. Consequently, a series of key CO₂ flooding technologies featuring full-reservoir coverage, full-scale adaptation, full-cycle optimization, and full-process integration have been formed. Field applications of the full-domain CO₂ flooding theory and associated technologies in the Xinjiang oilfield have demonstrated remarkable results, with the estimated recovery enhancement by over 20%. This theory provides a new idea/approach for the efficient development of various complex reservoirs in the Xinjiang oilfield, but also lays a theoretical foundation for the significant EOR in complex reservoirs across China. It is promising, industrially and economically, for application in other oilfields.

Key words: CO₂ flooding, full-domain flooding, multi-domain coupling, minimum miscibility pressure, injection and production regulation, EOR