高温交变应力作用下固井水泥石力学性能演变规律  

Evolution laws of mechanical properties of set cement subjected to alternating stress under high temperature

作　　者：冯少波[1] 叶素桃 张震 杨吕超 梁红军[1] 王银东 庞学玉 FENG Shaobo;YE Sutao;ZHANG Zhen;YANG Lyuchao;LIANG Hongjun;WANG Yindong;PANG Xueyu(Oil and Gas Engineering Research Institute,PetroChina Tarim Oilfield Company,Korla,Xinjiang 841000,China;School of Petroleum Engineering,China University of Petroleum-East China,Qingdao,Shandong 266580,China;State Key Laboratory of Deep Oil and Gas//China University of Petroleum-East China,Qingdao,Shandong 266580,China)

机构地区：[1]中国石油塔里木油田公司油气工程研究院 [2]中国石油大学(华东)石油工程学院 [3]深层油气全国重点实验室·中国石油大学(华东)

出　　处：《天然气工业》2025年第1期140-152,共13页Natural Gas Industry

基　　金：国家自然科学基金基础科学中心项目“超深特深层油气钻采流动调控”(编号:52288101);中央高校基本科研业务费专项资金资助项目“超深特深井固井液化学反应机理及调控方法”(编号:23CX05001A)。

摘　　要：固井水泥环作为井筒的重要组成部分,起着支撑套管、封隔不同层位地层和阻挡地层腐蚀性流体侵蚀套管的作用,长期承受着井下高温高压环境及特定工况下的交变载荷,其物理力学性能对井筒的长效封隔起着决定性作用。为此,针对极端服役环境下固井水泥石在交变载荷作用下的力学损伤和变形,开展了高温高压养护后水泥石单轴和三轴循环加载疲劳损伤研究,探索了测试温压条件及循环载荷应力水平等因素对水泥石力学性能的影响规律,揭示了水泥石在不同温压条件和循环载荷作用下的力学性能及变形特征演化规律,明确了水泥石疲劳损伤的控制机制,建立了水泥石疲劳强度预测模型。研究结果表明:(1)测试环境显著影响水泥石的力学性能和变形特征,高温高压环境降低了水泥石抗压强度和弹性模量,使水泥石在循环载荷作用下产生了明显的应变滞后现象以及更大的塑性应变;(2)交变应力作用下,第一周期的加载由于压实作用大幅提升水泥石的弹性模量,而且这种效应在高温高压环境下更为明显;(3)常温常压测试环境下,持续低强度的交变应力可以通过压实效应进一步提升水泥石的弹性模量,而高强度的交变应力则会造成材料损伤降低水泥石弹性模量;(4)高温高压交变应力作用下,水泥石加载模量除高应力状态外均较为稳定,卸载模量则呈现出明显下降的趋势。结论认为,该认识揭示了水泥石在不同温压条件和循环载荷作用下的力学性能及变形特征演化规律,为水泥环环空封隔失效机理和控制机制的深化研究奠定了理论基础。Cement sheath,as an important part of wellbore,plays a role supporting casing,isolating strata of different horizons,and preventing corrosive formation fluids from eroding the casing,and it suffers the downhole environment of high temperature and high pressure and the alternating load under specific working conditions for a long time,so its physical and mechanical properties are decisive to the long-term wellbore isolation.To clarify the mechanical damage and deformation of set cement under alternating stresses in the extreme service environments,this paper investigates the fatigue damage of set cement under uniaxial and triaxial cyclic loading after high-temperature and high-pressure curing,and explores the influence laws of testing temperature and pressure conditions and cyclic loading stress levels on the mechanical properties of set cement.In addition,the evolution laws of mechanical properties and deformation characteristics of set cement under different temperature and pressure conditions and cyclic loads are revealed,and the control mechanism of fatigue damage of set cement is clarified.Finally,a model for predicting the fatigue strength of set cement is established.And the following research results are obtained.First,the mechanical properties and deformation characteristics of set cement are significantly influenced by the testing environments.The set cement exhibits a decrease in compressive strength and elastic modulus when subjected to high-temperature and high-pressure environment.Cyclic loading results in the obvious phenomenon of strain hysteresis and the increase of plastic strain on the set cement.Second,under the action of alternating stress,the first loading cycle significantly boosts the elastic modulus of set cement due to the compaction effect.This effect is particularly pronounced in the high-temperature and high-pressure environment.Third,under ambient temperature and pressure,the continuous low-strength alternating stress can further increase the elastic modulus of set cement through comp

关 键 词：固井水泥 交变应力 高温高压 疲劳损伤 力学性能 变形特征 

分 类 号：TE256[石油与天然气工程—油气井工程]