固井水泥石徐变实验与分析  

EFFECT OF CREEPING ON LONG-TERM SEALING OF CEMENT SHEATH

作　　者：陶谦[1,2] 刘仍光[1,2] 周仕明[1,2] 丁士东[1,2] 

机构地区：[1]中国石化石油工程技术研究院 [2]页岩油气富集机理与有效开发国家重点实验室

出　　处：《钻采工艺》2016年第6期5-6,共2页Drilling & Production Technology

基　　金：国家自然科学基金面上项目(51374218)

摘　　要：测试了油井水泥石在不同载荷下的徐变值以及卸载后的残余应变,并评价了徐变对于固井水泥环长期密封性的影响。认为水泥环在套管长期挤压作用下持续产生徐变,当套管压力降低后弹性回缩,而水泥环由于徐变的产生卸压后存在残余应变,残余应变引起的拉应力超过水泥环与套管间的胶结强度而出现微环隙,引起水泥环长期密封性失效问题。The creeping and residual strain of oil well cement stone were measured under different loading values and during unloading.Effects of creeping on long-term sealing performance of cement sheath was evaluated.It was concluded that creeping in cement sheath was continuously developed by longterm squeezing of casing.When the casing pressure decreased,the casing would elastically retract,while the cement sheath still had the residual strain after unloading because of the creeping already produced.The tensile stress caused by the residual strain was higher than the bond strength between cement sheath and casing,which caused microcracks,resulting in the longterm sealing failure of the cement sheath.

关 键 词：徐变 水泥环 密封性 

分 类 号：TE256[石油与天然气工程—油气井工程]