疏松砂岩扩容力学性质研究

Study on Mechanical Properties of Unconsolidated Sandstone Dilatation

研究岩石扩容对注水井解除污染、恢复注入能力意义重大。通过循环加载测试了东营组砂岩的对数体积弹性模量,并测得其剪胀角,开展了疏松砂岩不同条件下扩容模拟实验。研究结果表明:渤海疏松砂岩对数体积弹性模量为0.0055,岩石黏聚力2.17 MPa,剪胀角58°,具备扩容变形的基础。通过改变地应力和水力注入条件,可以形成不同的岩石变形结果;在接近最小主应力的条件下,疏松砂岩地层可以形成高渗的扩容裂缝网,解除储层污染。

The study of rock dilatation is of great significance to the contaminant removing and injection capacity recovery of water in⁃jection wells.The reservoir rocks of Dongying Formation in Bohai oilfield were obtained.The logarithmic bulk elastic modulus of the Dongying Formation sandstone was tested by cyclic loading,and its dilatancy angle was measured.The simulation experiments of dilat⁃ancy of unconsolidated sandstone under different conditions were carried out.The results show that:the logarithmic bulk elastic modu⁃lus of the unconsolidated sandstone is 0.0055,the rock cohesion is 2.17 MPa,and the dilatancy angle is 58°,which shows that the un⁃consolidated sandstone has the foundation of dilatancy deformation.Different rock deformation results can be formed by changing the in-situ stress and hydraulic injection conditions;under the stress condition close to the minimum principal stress,a high-permeability dilatation fracture network can be formed in the unconsolidated sandstone formation to remove reservoir pollution.