深层致密砂岩储层岩石结构面微观力学行为特征

Micro-mechanical behavior characteristics of rock structure surface
for deep tight sandstone reservoir

张冲 谢润成 姚勇 吕晶 曹茜

成都理工大学能源学院，四川 成都 610059 成都理工大学油气藏地质及开发工程国家重点实验室，四川 成都 610059

College of Energy Resources, Chengdu University of Technology, Chengdu 610059, China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China)

深层致密砂岩结构面的力学行为易被忽视。通过岩心物性资料、岩石力学实验分析了孔隙影响岩石破裂的基本特征，确定了岩石破裂的孔隙度下限为2.21%，与研究区储层孔隙度下限2%基本吻合，而物性下限对应的临界抗张强度为6.46 MPa，也与研究区砂岩平均抗张强度基本一致。加载方向平行于纹层时，岩石更易发生破裂。微裂隙力学变形实验表明，存在微裂隙的岩石首次加载￣卸载后，平均形变恢复比小于35%，张开度明显减小。该研究从微观角度揭示了岩石结构面对岩石破裂和变形的基本力学行为，可为裂缝控制因素分析、预测及其有效性评价提供重要依据。

The mechanical behavior of structure surface for deep tight sandstone is easily overlooked. Based on core physical property data and rock mechanical experiment, this paper analyzes the basic characteristics of the effect of pore on rock rupture and determines the physical property lower limit of rock rupture to be 2.21%, which is basic consistent with the lower limit of reservoir porosity of 2% in this study area. Its corresponding critical tensile strength is 6.46 MPa, which is also consistent with the average tensile strength of sandstone. When stress loading direction is parallel to the lamina, rock is more likely to rupture. The micro fracture deformation experiments results show that after the first loading?鄄unloading of rock, the average deformation recovery is less than 35% and the degree of opening reduces obviously. The study reveals the basic mechanical behavior of rock structure surface on rock rupture and deformation from microscopic point of view, which can provide important microscopic evaluation basis for the control factor analysis,prediction and effectiveness evaluation of fracture.

10.6056/dkyqt201405004