摘要
在多次循环注采条件下,储气库的储层和盖层往往会受到交变载荷作用,孔隙压力的改变使岩石力学性质发生改变,从而导致储气库圈闭密封性发生变化。为了保障储气库安全高效运行,文中通过开展三轴循环加卸载同步渗透率测试实验,建立了储层与盖层的损伤本构模型,研究了岩石在循环载荷作用下的强度、渗透率变化规律和损伤规律。研究结果表明:在外力作用下,砂岩较容易形成连通裂缝而被破坏,而泥岩由于水化膨胀作用渗透率减小,不容易产生连通裂缝。最大加载应力达到峰值强度的65%~70%条件下,初始压实阶段砂岩渗透率会急速下降,到达一定程度后,渗透率又会逐渐上升,说明砂岩内部裂缝逐渐发育;而对于泥岩,每次应力加载后,渗透率都会先增大、后减小,直至泥岩试样被破坏,说明泥岩在产生裂缝后因水化膨胀作用而裂缝闭合。随着应力循环加卸载次数增多,岩石残余应变、损伤变量会越来越大,导致岩石被破坏。
Under the condition of multiple rounds of cyclic injection and production in gas storage,the reservoir and cap rock are often subjected to alternating load.Due to the change of pore pressure,the mechanical properties of rocks are changed,resulting in the change of trap sealing of gas storage.In order to ensure the safe and efficient operation of gas storage,the strength,permeability and damage evolution law of rock under cyclic loading effect are studied by carrying out permeability measurement test under triaxial cyclic loading and unloading and establishing the damage constitutive model of reservoir and cap rock.The results show that under the action of external force,sandstone is easy to be damaged because of connected fractures production.The permeability of mudstone decreases due to hydration and expansion,so it is not easy to produce connected fractures.When the maximum loading stress reaches 65%-70%of the peak strength,the permeability of sandstone will decrease rapidly in the initial compaction stage and then increase gradually after reaching a certain degree,indicating that the internal fractures of sandstone are gradually developed.After each stress load,the permeability of mudstone will first increase and then decrease until the mudstone sample is damaged,indicating that the fracture is closed due to hydration and expansion after the fractures occur.When cyclic times of loading and unloading stress increase,the residual strain and damage variables of rock become larger and larger,resulting in rock failure.
作者
张广权
范照伟
曾大乾
张俊法
冒海军
糜利栋
贾跃玮
杨小松
敬霄
ZHANG Guangquan;FAN Zhaowei;ZENG Daqian;ZHANG Junfa;MAO Haijun;MI Lidong;JIA Yuewei;YANG Xiaosong;JING Xiao(Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China;Wuhan Institute of Geotechnical Mechanics,Chinese Academy of Sciences,Wuhan 430071,China;School of civil engineering and architecture,Southwest University of Science and Technology,Mianyang 621010,China)
出处
《断块油气田》
CAS
CSCD
北大核心
2021年第6期769-774,共6页
Fault-Block Oil & Gas Field
基金
中石化科技部项目“复杂地质条件下储气库建库及安全高效运行技术研究”(P21024)。
关键词
储气库
交变载荷
渗透率
循环加卸载
损伤规律
gas storage
alternating load
permeability
cyclic loading and unloading
damage law
