胜利油田高89区块低渗油藏CO2近混相驱替机理研究

低渗透油藏中CO2驱较难实现混相,而非混相驱驱替效率较低。为实现高效率非混相驱油,以胜利油田高89区块油藏为对象,研究了CO2近混相驱技术可行性及提高采收率机理。通过PVT实验和细管实验,确定了油藏原油的最小混相压力;通过不同相态下的岩心驱替实验,研究了相态变化对CO2驱替效率的影响;通过油藏数值模拟分析了CO2近混相驱提高采收率的机理。实验结果表明,近混相驱与混相驱相似,同样具有溶解、抽提等作用,对于较难实现混相驱的低渗透油藏,近混相驱同样可以达到较好的开发效果。

The mechanism of quasi-miscible CO2 flooding in Block G89 low permeability reservoir of Shengli oilfield

It is difficult to achieve CO2 miscible flooding in low permeability reservoirs and immiscible flooding is low efficiency.The low permeability reservoirs in Block Gao89 of Shengli oilfield are selected to study the feasibility of quasi-miscible CO2 flooding and its mechanism in enhancing oil recovery.PVT and slim tube experiments are conducted to determine the minimum miscibility pressure;the effects of phase behavior on displacement efficiency of CO2 flooding are studied by core displacement experiments;and the EOR mechanism of quasi-miscible CO2 flooding is analyzed by numerical simulation.The results indicate that quasi-miscible flooding is similar to miscible flooding in respects of dissolution and extraction.For those low permeability reservoirs difficult to realize miscible flooding,quasi-miscible flooding is an effective way.