三轴应力下固井界面窜流机理及影响因素实验研究

Experimental study on channeling mechanism and influencing factors at cementing interface under triaxial stress

良好的固井水泥环封隔能力是保障多层系油田分层注采效果的关键因素。在分析固井界面封隔失效机理及影响因素的基础上,创建了一种三轴应力条件下固井水泥环封隔能力评价方法,开展了不同影响因素对固井水泥环封隔能力的测试实验。研究结果表明:固井界面胶结能力越强,水泥环有效封隔长度越长,地层水平最小主应力越大,水泥环界面突破值越高,封隔能力越强,分层开采时极限隔层厚度越小。三轴应力下固井界面窜流机理及影响因素实验研究结果可为分层注水、返层封堵选层提供理论支撑。

Good sealing isolation ability of cementing sheath is the key factor to ensure the effect of separate layer injection and production in multi-layer oilfield.On the basis of analyzing the sealing failure mechanism and influencing factors at the cementing interface,a new evaluation method for the sealing ability of cementing sheath under triaxial stress was established,and the experiment on the sealing ability of cement sheath under different influencing factors was carried out.The results showed that the stronger the bonding ability at cementing interface,the longer the effective sealing length of cementing sheath,the greater the minimum horizontal principal stress in the formation,the higher the breakthrough value of cementing sheath interface,and the stronger the sealing ability of cementing sheath,and the smaller the limit thickness of interbed in separate layer production.The experimental study on the channeling mechanism and influencing factors at cementing interface under triaxial stress can provide theoretical support for layer selection in separate layer water injection and backflow plugging.