非线性流下变形介质油藏压裂井产能评价

针对变形介质低渗油藏特征,根据压裂后流体渗流变化规律,基于稳定渗流理论,建立了考虑启动压力梯度、应力敏感共同影响下的低渗油藏垂直裂缝井产能方程。在建立模型基础上,分析了启动压力梯度、渗透率变形系数、地层污染等对产能、采油指数的影响关系。研究表明:启动压力梯度和应力敏感效应使油井产能下降,随着启动压力梯度增大,油井产能下降的幅度随压差增大而减小,而随着渗透率变化系数增大,油井产能下降幅度随压差增大而增大;地层污染导致油井产能下降幅度随压差增大而增大;当生产压差较小时,启动压力梯度的影响显著,而生产压差较大时,应力敏感效应影响明显增强;在变形介质油藏实际开发中应考虑选择合理生产压差。

Production Evaluation of Fractured Wells in Deformed Reservoirs with Non-linear Seepage

In view of the characteristic of deformed low permeability reservoirs,based on the change of fluid flow rule after fracturing,established is a productivity equation for vertical fracture wells in low permeability reservoirs considering the common effect of the start-up pressure gradient and stress sensitivity by using the steady seepage theory.Based on the established productivity equation,analyzed are effects of the start-up pressure gradient,permeability deformation coefficient,formation contamination,etc.on productivity and oil well production index.The results show that oil well productivity decrease will be resulted from effects of start-up pressure gradient and stress sensitivity.When the start-up pressure gradient increases,oil well productivity decrease magnitude will reduce gradually and when the permeability deformation coefficient increases,oil well productivity decrease magnitude will increase gradually and formation contamination will result in increase of oil well productivity decrease magnitude.If production pressure is small,effect of start-up pressure gradient is great and stress sensitivity effect will increase as the production pressure increases.A reasonable production pressure shall be selected in actual development of deformed reservoirs.