低渗透复杂断块油藏套损机理及数值计算

Casing failure mechanism and numerical calculation for low permeability and complex fault block reservoirs

孙铭新¹ 程远方² 贾江鸿¹ 闫振来¹ 周延军¹

中国石化集团胜利石油管理局钻井工艺研究院，山东 东营 257017 中国石油大学（华东）石油工程学院，山东 青岛 266580

低渗透复杂断块油藏在长期注采开发过程中，套管损坏问题日趋突出，严重制约着这类油藏的高效开发。文中分析认为，这类油藏注采开发中，套管损坏的原因主要有拉伸、挤压和剪切损坏等3种。基于油藏流固耦合理论，建立了流固耦合渗流场、变形场计算模型，并应用于A油田B断块，以模拟低渗透复杂断块注采过程中地层变形及套管应力分布规律。结果表明，模拟与实际套损情况符合3口，误判1口，符合率为75%，验证了本模型的准确性，同时验证了受断层遮挡作用，断层附近地层会出现较大横向位移，极易产生不平衡有效应力场，从而使套管发生损坏的判断。因此，建议在断层附近尽量提高套管的抗挤毁能力，以有效提高套管寿命。

Casing failure is becoming increasingly prominent in the process of oilfield development for low permeability and complex fault block reservoirs, which severely restricts the efficient development of low permeability reservoirs. The cause of casing failure is studied, which includes tension failure, extruding failure and shear failure. The calculation model of fluid-solid coupling seepage fields and deformation field is established based on fluid-solid coupling theory. After case analysis of B Block in A Oilfield, the law of reservoir deformation and casing stress distribution is simulated in the process of injection and production. The calculating results accord with the actual casing failures for 3 wells. One well is failed with accuracy rate of 75%. It is also further verified that an imbalance of effective stress field is easily caused and the lateral displacement of formation is increased near the fault, which results in casing failure. Therefore, in order to increase casing life, its anti?鄄collapsing ability should be improved near the fault.

10.6056/dkyqt201206028