Potential Evaluation of CO₂ Sequestration and Enhanced Oil Recovery of Low Permeability Reservoir in the Junggar Basin, China

The Chinese government is seeking CO 2 gas emission reduction measures. CO 2 capture and geological sequestration is one of the main measures. Injecting CO 2 into oil reservoirs can not only achieve the environmental protection purpose of CO 2 geological sequestration but also improve oil recovery and realize economic benefits, which helps to offset the cost of CO 2 sequestration. Therefore, the oil reservoir is one of the best sites for CO 2 sequestration. As for the reservoir of CO 2 flooding after water flooding, there are two methods for evaluating the potential of CO 2 enhanced oil recovery (EOR) and sequestration capacity, which are the mass balance method and analogy method. Through a combination of these two methods, this paper presents a new method, which can be reasonably used to evaluate these potentials. Besides, the screening criteria of CO 2 sequestration and EOR in the Junggar Basin are also proposed. On the basis of the guidelines of CO 2 source matching, reservoir characteristics, and fluid characteristic, four typical low permeability reservoirs (Caiman oil reservoir, Karamay oil reservoir, Beisantai oil reservoir, and Luliang oil reservoir) of the Junggar Basin are selected to study their potential of CO 2 EOR and sequestration. And then the potential of CO 2 EOR and sequestration capacity for the Junggar Basin oil reservoirs of CO 2 flooding after water flooding is studied by applying the method mentioned above. For 275 development blocks of 24 oil fields in the Junggar Basin, 139 development blocks are suitable for CO 2 miscible flooding EOR and sequestration, whereas 136 development blocks are suitable for CO 2 immiscible flooding EOR and sequestration. The total EOR potential could be 18 407.76 × 10 4 t and the CO 2 sequestration potential could amount to 47 486.0 × 10 4 t. The evaluation results show that the Junggar Basin’s oil reservoirs are suitable sites for CO 2 EOR and sequestration and have great potentials. It can provide the decision basis for the future implementation of CO 2 emission reduction projects in Western China.