基于双剪统一强度理论的垂直井井壁坍塌压力解  

Collapse pressure solution of vertical wellbore based on twin-shear unified strength theory

作　　者：崔莹[1,2] 屈展[1,2] 赵均海[3] 王萍[1] 

机构地区：[1]西安石油大学土木工程系,陕西西安710065 [2]西北工业大学航空学院,陕西西安710072 [3]长安大学建筑工程学院,陕西西安710061

出　　处：《广西大学学报（自然科学版）》2016年第2期346-354,共9页Journal of Guangxi University（Natural Science Edition）

基　　金：国家自然科学基金资助项目(51174162);陕西省教育厅专项科研计划项目(15JK1561);西安石油大学青年科技创新基金项目(2015BS17)

摘　　要：针对钻井过程中井壁坍塌压力的理论计算值与实测值存在较大差异的问题,依据井壁力学模型和双剪统一强度理论,通过理论分析和实践验证,推导得出了不考虑渗透作用的垂直井井壁坍塌压力统一解表达式,并分析了不同b值、不同深度、不同强度准则下井壁坍塌压力的变化趋势。结果表明:当井深一定时,随着b值的增大,井壁坍塌压力相应降低。同一b值条件下,随着井深的增加,井壁坍塌压力相应提高。中间主应力对浅层井壁坍塌压力的影响较深层大,中间主应力的引入对井壁岩石强度的提升有着积极作用。文中建立的井壁坍塌压力解公式可以通过改变b值的大小调整中间主应力的贡献,以适应不同地质条件下垂直井井壁的坍塌压力计算。As the theoretical values for collapse pressure of vertical wellbore were quite different from the actual measured values,based on the twin-shear unified strength theory and the mechanical model of wellbore rock,a computational method for collapse pressure of vertical wellbore without considering the penetration of wellbore was analyzed and discussed. The unified formula of the collapse pressure was deduced and proved by analyzing the different factors,such as different b values,different depths of wellbore and different strength criteria. The results show that,under the conditionof wellbore depth being unchanged,the collapse pressure decreases with the increase of b value. Also,under the condition of b value being unchanged,the collapse pressure increases with the increase of wellbore depth. The results also show the intermediate principal stress has greater impact on the collapse pressure of shallow borehole than that of deep one. And the deduced solution considering the intermediate principal stress has active meaning to the ultimate strength of rock. The proposed unified formula of the collapse pressure based on the twin-shear unified strength theory can meet different geological conditions by changing the value of b.

关 键 词：双剪统一强度理论 井壁稳定 坍塌压力 中间主应力 

分 类 号：TU452[建筑科学—岩土工程]