矿物成分和微结构对泥质岩储层应力敏感性的影响

富含粘土的页岩、泥质粉砂岩和粉砂岩等泥质岩的储层矿物成分、微组构和微孔结构复杂，使得泥质岩储层的应力敏感性存在较大差别。以鄂尔多斯盆地延长组泥质岩为研究对象，开展应力敏感性实验评价研究，并与典型致密砂岩储层进行对比。结果表明，页岩的应力敏感程度强，泥质粉砂岩中等—偏强，致密砂岩弱；在30MPa有效应力作用下，岩石呈现塑性变形。分析指出，岩石的变形主要受到岩石的组分、胶结物类型和含量\,微裂缝系统、孔隙结构参数、骨架颗粒形态、接触方式\,粒度分布、粘土微结构等参数的影响。针对3类岩石的应力敏感性差异，应区别对待，尽力控制储层应力敏感性损害的发生。

Effects of Mineral Composition and Microstructure on Stress-sensitivity of Mudrocks

The mudrocks which are rich in clays have the differences of stress sensitivity,because of the complexity of mineral composition,micro-construction and microporous-structure.This paper carried out a study of stress sensitivity evaluation on clay shale and sandstone reservoirs of Yanchang Group in Ordos basin and compared the differences of stress sensitivity.The results showed that: shale has a strong stress sensitivity; silty sandstone has a medium-partial strong stress sensitivity; tight sandstone has a weak stress sensitivity; under the effective stress of 30MPa,the rock presents plastic deformation.Rock deformation is mainly affected by the composition of rock,cementing type and content,micro-fracture system,pore structure parameters,morphology contacting way and distribution of the particles,and clay mineral content and microstructure.The stress sensitivity differences of the three rocks reflect the influence of the composition and microstructure of mineral rock on stress sensitivity.Therefore,for different lithologic reservoirs,reasonable production pressure difference should be adopted to avoid the occurrence of reservoir stress sensitivity damage.