饱和水泥石力学特性及其对水泥环完整性的影响  

Mechanical properties of saturated set-cement and their impact on cement sheath integrity

作　　者：郭辛阳[1] 王晨阳 张一凡 张洋洋[1] 许玉强[1] GUO Xinyang;WANG Chenyang;ZHANG Yifan;ZHANG Yangyang;XU Yuqiang(Key Laboratory of Unconventional Oil&Gas Development,Ministry of Education,State Key Laboratory of Deep Oil and Gas,School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,China)

机构地区：[1]中国石油大学(华东)石油工程学院,深层油气全国重点实验室,非常规油气开发教育部重点实验室,山东青岛266580

出　　处：《实验技术与管理》2025年第2期81-87,共7页Experimental Technology and Management

基　　金：国家自然科学基金基础科学中心项目(52288101);国家自然科学基金青年项目(51704325);中国石油大学(华东)本科教学改革重点项目(CZ2022005);中国石油天然气股份有限公司科技项目(2023ZG18)。

摘　　要：采用单轴和三轴力学实验研究了饱和水泥石在不同围压和循环载荷下的力学特性及不同弹性模量饱和水泥石在不同围压下的力学特性,分析了其对水泥环完整性的影响。实验结果表明,单轴条件下,饱和水泥石与自然含水水泥石力学特性类似;围压条件下,饱和水泥石力学特性与有效应力密切相关,随着有效应力的增大,屈服应力增大,抗压强度增加,残余强度增加,塑性变形能力增强,更不易形成微间隙和微裂缝,更有利于水泥环的完整性;单轴和围压条件下,循环载荷越大,单次循环载荷造成的塑性应变越大,相同循环载荷时围压条件下的塑性应变比单轴条件更大。[Objective]The cement sheath,located between the casing and formation or between casings,serves as the primary barrier for zonal isolation,and its integrity is critical for wellbore integrity.Existing studies have demonstrated the significant influence of the mechanical properties of cement on sheath integrity.Extensive research has been conducted domestically and internationally,testing the stress–strain curves of cement under uniaxial and triaxial conditions and calculating the parameters,such as the elastic modulus and Poisson's ratio,primarily using the Coulomb–Mohr criterion.However,limited research exists on the mechanical properties of fully saturated cement,which is crucial for understanding wellbore conditions.[Methods]The cement slurries used in the experiments were formulated according to the American Petroleum Institute(API)Spec-10B standards,which utilizes the cement slurry recipe employed in oil fields.Cement samples were prepared under both natural water content and saturated conditions.Uniaxial and triaxial mechanical tests were conducted on the cement samples,with the mechanical properties of the naturally hydrated cement samples serving as a comparison baseline for studying the mechanical characteristics of the saturated cement samples.The mechanical experiments under uniaxial and triaxial conditions were carried out using the GCTS RTR-2000 triaxial testing machine from the United States.When analyzing the mechanical properties of the cement sheath under different confining pressures and cyclic loading conditions,particular attention was given to the parameters closely related to plastic deformation and fracture of the cement,such as the yield conditions,compressive strength,and residual strength.For comparison with the saturated cement samples,the complete stress–strain curves of two types of cement,namely low-density cement and conventional-density cement,under natural water content were tested at different confining pressures.Mohr's circles under various confining pressures were plotted

关 键 词：饱和水泥石 力学特性 循环载荷 完整性 

分 类 号：TE256[石油与天然气工程—油气井工程]