Evaluation of Carbon Dioxide Flooding in Reservoir of Extra Low Permeability—Case Study in Wangyao Chang6 Reservoir of Ansai Oil-Field

Abstract

The Triassic Chang6 extra-low permeability reservoir in Ansai Oilfield has entered the period of medium to high water cut, and the contradiction of water flooding development is increasingly prominent. The single water flooding development has limited space to improve the output of a single well, and CO2 can reduce the interfacial tension and capillary resistance between the injected medium and the formation crude oil, thus effectively improving the oil displacement efficiency. For a good quality of the oil in Ansai Oilfield, the characteristics of the reservoir structure stability, to explore a new mode to enhance oil recovery of CO2 and has conducted the related evaluation and numerical simulation of indoor carbon dioxide scheme optimization, The suitable CO2 injection process and reasonable injection parameters were optimized. On the basis of the experimental area of CO2 injection, forecast the oil displacement effect of water alternating injection method is higher than pure gas displacement amplitude increase recovery efficiency, The increase of slug quantity prolongs the breakthrough time of CO2. The identified alternative development scheme for carbon dioxide flooding can improve recovery by more than 10% compared with water flooding.