特低渗油藏启动压力梯度新的求解方法及应用

对长庆油田三叠系油藏25块不同渗透率岩心(渗透率为0．022～8．057mD,多数小于1mD)进行室内驱替实验,获得实测启动压力梯度。依据考虑启动压力梯度后的一维非达西定律,对实验数据进行回归分析,获得了低渗透岩心的启动压力梯度与地层平均渗透率的幂函数关系式,绘制了启动压力梯度与渗透率关系的双对数坐标理论图版。利用实验得到的回归关系式和求解启动压力梯度的理论图版,结合低渗透油田实际,得到不同生产压差下确定极限注采井距的双对数坐标理论图版,可为低渗透油田开发确定合理井网密度提供理论依据。图3表1参10

A new solution and application of starting pressure gradient in ultra-low permeability reservoir

Laboratory displacing experiments about actual starting pressure gradient were done on 25 cores with different permeability (the values range between 0.022-8.057mD, mostly lower than 1mD), from Triassic reservoir in the Changqing Oilfield. The relationship formulae between the starting pressure gradient and average permeability of stratum are regressed from the experiment and some theoretical plates showing the relationships between the starting pressure gradient and permeability are drawn in logarithmic coordinate according to the non-Darcy law considering the existence of the starting pressure gradient of single-dimension flow. The theoretical plates, obtained from the regressed relationship formulae from the experiments and those theoretical plates solving the starting pressure gradient combined with the reality of the low-permeability oilfield, would be able to present some theoretical foundations to development of low-permeability reservoir.