不同填充模式裂缝型致密储层应力敏感性定量研究

Quantitative study of stress sensitivity for fractured tight reservoir with different filled patterns

为了解不同裂缝填充模式下致密储层渗透率应力敏感性的变化规律,并进一步将其应用于油藏动态分析及产能优化工作中,进行了不同裂缝填充模式下致密岩心孔隙度和渗透率应力敏感性实验,对比分析了各种裂缝填充模式岩心孔隙度和渗透率应力敏感性曲线差异性。同时,基于渗流理论推导出了不同有效应力条件下裂缝系统渗透率理论计算模型,对实验结果进行了解释分析。研究结果表明:不同裂缝填充模式岩心渗透率应力敏感性由强到弱依次为不填充岩心、半填充岩心、全填充岩心、基质岩心;渗透率应力敏感性受岩心基质压缩、裂缝闭合及填充物支撑共同影响,在不同裂缝填充模式下,主导影响因素不同;裂缝填充模式岩心的渗透率应力敏感性过程可分为2个阶段,第1个阶段,有效应力较小,岩心受有效应力影响,同时发生裂缝系统闭合和基质压缩现象,第2个阶段,岩心受压到一定程度,岩心渗透率应力敏感性主要表现为基质渗透率应力敏感性,岩心渗透率下降速率变缓。

To understand the law of permeability change caused by eftective stress and thrther use it to analyze dynamic reservoir and opitimize production, experiments on fractured tight cores with different filled patterns to nleasure the variation of porosity and permeability are done. Differences of the permeability and porosity sensitivity curves are analyzed. Based on the seepage law and related theories, a quantitative model for permeability stress sensitivity of tight cores are built, and the results are analyzed. The results show that the stress sensitivity of cores with different filled patterns from the strongest to the weakest is unpacked cores, partly-packed cores, packed cores and matrix; stress sensitivity of such a core is an outcome of combination of matrix compression, fracture closure and supporting from the fillers. The dominate factors are difterent with difterent filled patterns. The permeability stress sensitivity can be divided into two stages, in the first one, relatively low eftective stress, both the closure of fractures and matrix compressibility play the dominate role; in the later one, the matrix compressibility plays the key role in determination of permeability stress sensitivity-, and the decrease of permeability becomes smooth in this stage.