裂缝性特低渗油藏井网调整优化研究

Research on Well Pattern Adjustment and Optimization in Ultra-low Permeability Fractured Reservoir

特低渗油藏由于天然裂缝发育、储层非均质性严重,开发过程中常表现出油井暴性水淹、采出程度低等矛盾。对于特低渗油藏菱形反九点井网,在数值模拟中引入低渗透油藏启动压力梯度和各向异性,同时以加密的形式对开发中后期的井网进行调整,预测并对比井网调整后不同加密方式的开发效果,探讨适用于裂缝性特低渗油藏菱形反九点井网合理最优的井网加密调整方式。模拟结果表明,将菱形反九点井网加密调整为小井排距正方形反九点井网,能够有效提高井网采出程度、延缓裂缝性见水,取得最优的开发效果;加密对井排距较大的井网开发效果起到改善作用,加密后老井的单井产能下降趋势及含水率上升趋势受到抑制;对于菱形反九点井网来说,不同加密形式对应的加密效果不同。研究成果为特低渗透油藏的高效开发提供了一定的理论基础。

The development of ultra-low permeability reservoir is often accompanied by rapid water conning of production wells and low recovery percent of reserves due to developed nature fractures and strong reservoir heterogeneity.Rhombus anti nine-spot well pattern is commonly used in the ultra-low permeability reservoir with nature fracture.During the well pattern adjustment in the middle-late development stage,threshold pressure gradient and anisotropy was taken into account in the process of numerical simulation,and infill was done.The result of well pattern adjustment with various infill forms was forecasted and compared.The purpose is to figure out the best way of infill for this kind of reservoir.The simulated result shows that square anti nine-spot well pattern with small well spacing and row spacing is the best because it can increase the re-covery percent of reserves and delay water breakthrough effectively.Besides,the infill can improve the development effect of the rhombus anti-nine-spot well pattern with large well spacing and row spacing.The ten-dency of decline of the productivity and rise of the water cut of the single old well is suppressed after in-filling.Various infill forms bring various effects.This research provides certain theory basis for the efficient de-velopment of the ultra-low permeability reservoirs.