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目前,国内外对启动压力梯度的研究主要集中在油水两相中,对于油气两相启动压力梯度研究很少。用特低渗透油藏的天然岩心,通过实验研究了不同流体,不同介质及不同注气条件下气驱油启动压力及其变化规律。研究结果表明:油气两相启动压力梯度随渗透率的增加而降低,与流体的流度呈半对数直线关系;随含油饱和度的降低而增加;有效应力对启动压力梯度影响很大;启动压力梯度随着回压的增加而降低,但幅度不大。
At present, the research on the start-up pressure gradient at home and abroad mainly focuses on the oil-water two-phase, and few studies on the pressure gradient of the start-up of oil-gas two-phase. By using natural cores of ultra-low permeability reservoirs, the startup pressure and its variation of gas-flooding under different fluids, different media and different gas injection conditions were studied experimentally. The results show that the pressure gradient of the oil-gas two-phase start-up decreases with the increase of permeability, and is semi-logarithmically linear with the fluid flow rate; increases with the decrease of oil saturation; effective stress has a great influence on the start-up pressure gradient; The pressure gradient decreases with the increase of backpressure, but the magnitude is not large.