中文摘要：

致密砂岩气藏在开采时因地层能量衰竭导致有效应力增加,储层物性相应地发生变化,其电学参数也随之改变.以往在常规围压下进行的岩电实验,其结果包含了岩样微裂缝等因素对电阻率的贡献,获取的电学参数不能客观反映原地储层性质.本文以鄂尔多斯盆地上古生界二叠系典型致密砂岩气藏为研究对象,测定了不同有效应力下完全饱和地层水71块致密砂岩样品的电学参数.结果表明,岩样电阻率随有效应力增加而变大,且与常规砂岩相比,致密砂岩电学性质受有效应力影响更大;随有效应力增加,岩性系数a增大,地层胶结指数m减小,原地有效应力（25.86MPa）下a和m分别是常压（3.5MPa）下的2.7和0.7倍;高有效应力状态下,电阻率达到稳定值所需测试时间更长;电阻变化幅度直观表征了其骨架结构变形程度,也是致密砂岩应力敏感时间效应的直接体现.因此,应根据储层原地有效应力确定致密砂岩气藏的电学参数.

英文摘要：

Producing energy depletes with the development of tight sandstone gas reservoir,which results in the increase of effective stress and the change of its physical properties as well as rock-electro parameters.Generally speaking,conventional rock-electro experiment which primarily contains the effect of microcrack on rock resistivity neglects the importance of in-situ condition.Therefore,the rock-electro parameters obtained by conventional rock-electro experiment couldn＇t reflect the real properties of reservoir under in-situ condition.71 typical tight sandstone core plugs from Upper Palaeozoic in Permian in Ordos basin were used in this study to measure the rock-electro parameters under different effective stress.The experimental results indicate that rock resistivity increases with the increase of effective stress,and the influence of effective stress on rockelectro properties of tight sandstone is more evident than that of conventional sandstone.The experimental results also indicate that rock-electro parameter aincreases and m decreases with the increase of effective stress,and the parameter aand m under in-situ condition is 2.7and 0.7times over those under conventional pressure respectively,that it would take much more time for rock resistivity to reach a stable value under high effective stress,and that the magnitude of rock resistance change reflects the degree of matrix deformation apparently,which also reflects the time effect of stress sensitivity for tight sandstone.Therefore,the rock-electro parameters should be determined under in-situ condition.