基于多孔介质理论的油井水泥石破坏准则  

A Failure Criterion of Oil Well Set Cement Based on Porous Media Theory

作　　者：丁嘉迪 沈吉云 张硕 纪宏飞[2] 王琳琳 DING Jiadi;SHEN Jiyun;ZHANG Shuo;JI Hongfei;WANG Linlin(China Oilfield Services Ltd.COSL Oilfield Chemicals,Sanhe,Hebei,065201;CNPC engineering Technology R&D company limited,Beijing 100101;China university of petroleum,Beijing 100083)

机构地区：[1]中海油服油田化学研究院,河北三河065201 [2]中国石油集团工程技术研究院有限公司,北京100101 [3]中国石油大学(北京),北京100083

出　　处：《钻井液与完井液》2020年第6期763-770,共8页Drilling Fluid & Completion Fluid

摘　　要：水泥石是一种由水泥骨架和孔隙组成的多孔介质,井下水泥凝固水化后,孔隙中还会有自由水存在,并且与地层相通,所以水泥石力学行为会受到地层孔隙水压和外部载荷的影响。为进一步揭示油气井实际工况下水泥石的力学性能,引入多孔介质力学理论,对水泥石力学性能进行三轴力学实验研究,获得相关参数,从而确定了考虑孔隙水压的水泥石摩尔-库伦破坏准则。实验以嘉华油井水泥作为研究对象,通过改变围压、排水条件以及孔隙水压获得水泥石的各项力学参数。结果显示,孔隙水压是影响水泥石破坏强度的重要因素;不考虑多孔介质力学的水泥石摩尔-库伦准则模型为非线性;考虑多孔介质力学理论的水泥石摩尔-库伦包络线为线性并获得准则公式。Set cement is a porous medium comprising cement skeleton and pores.When becoming solidified after hydration,the set cement in a well still has free water in its pores,and the free water is connected with fluid in the formations.Hence,the mechanical behavior of a set cement is influenced by the pore pressure of the formation and the external loads.To further reveal the mechanical performance of set cement in actual working conditions,triaxial mechanical experiment was conducted on set cement based on the guidance of the theory of porous media mechanics.Data obtained from the experiments were used to determine the Mohr-Coulomb failure criteria taking into account the pore water pressure.The experiments were conducted on Jiahua oil well cement.By changing the confining pressure,water drain conditions and pore water pressure,various mechanical parameters of the set cement were obtained.It was found from the experimental results that the pore water pressure is an important factor affecting the failure strength of the set cement.The Mohr-Coulomb criteria model not taking into account the porous media mechanics of the set cement are non-linear,while the Mohr-Coulomb envelope taking into account the porous media mechanics of the set cement are linear,from which the criterion formulae were calculated.

关 键 词：水泥石 多孔介质力学 摩尔-库伦准则 三轴实验 孔隙水压 排水 不排水 

分 类 号：TE256.9[石油与天然气工程—油气井工程]