降低特低渗透油层启动压力机理分析

Analysis of mechanisms of lowering trigger pressure of extra low permeability reservoirs

分析了低渗透岩心在水驱、注表面活性剂、后续水驱的过程中 ,水驱压力随注入孔隙体积倍数的变化曲线 ;根据压差与流量的关系 ,研究了降低低渗透油层启动压力的机理 .结果表明 :利用与油藏条件配伍的活性剂体系可降低低渗透岩心的驱替压力 ,并在后续水驱过程中不回升 ;注入与原油可产生超低界面张力的表面活性剂体系 ,能提高岩心的相对渗透率和可流动渗透率 ,可起到降低启动压力梯度的作用 .

This paper analyzed the curve variation of injection pressure versus pore volume of injected water for low permeability cores in the course of water flooding, surfactant flooding and subsequent water flooding . Mechanism of lowering trigger pressure of low permeability reservoirs was investigated according to the relation between pressure differential and flow rate. Results show that surfactant system compatible with reservoir conditions can lower the driving pressure of low permeability cores and prevent it from rising again in the course of subsequent water flooding. By injecting surfactant system capable of generating extra-low interfacial tension ,the relative permeability and effective permeability of low permeability cores can be increased and the gradient of trigger pressure can be lowered.