储气库井水泥环密封性失效试验研究  

Experimental Study on Sealing Failure of Cement Sheath in Gas Storage Wells

作　　者：赵春 贺梦琦 陈显学 汪衍刚 刘长环 冯永存 李晓蓉[2] Zhao Chun;He Mengqi;Chen Xianxue;Wang Yangang;Liu Changhuan;Feng Yongcun;Li Xiaorong(Liaohe Oilfield(Panjin)Underground Gas Storage Co.,Ltd;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing))

机构地区：[1]辽河油田(盘锦)储气库有限公司,辽宁省盘锦市124000 [2]中国石油大学(北京)油气资源与探测国家重点实验室

出　　处：《石油机械》2024年第6期78-85,共8页China Petroleum Machinery

基　　金：国家自然科学基金青年科学基金项目“分布式光纤声传感(DAS)监测水泥环完整性研究”(52004298)。

摘　　要：循环注采气会对储气库井水泥环产生周期性载荷作用,易导致水泥环密封失效。以H储气库井水泥环密封失效为背景,开展了水泥石循环加卸载及水泥石力学、孔渗测试,获得了水泥石循环加载后的微观结构CT形态,进行了全尺寸水泥环密封失效试验。试验结果表明:经过30轮次循环加载后水泥石力学性能降低、气体渗透能力增加,但依然能有效阻止气体从水泥基质泄漏;循环加卸载会造成水泥石微观结构损伤进而产生累积塑性应变,循环轮次越多累积塑性应变越大;循环加卸载后,水泥石CT扫描形态显示,水泥石中出现微观结构损伤,水泥石微观损伤程度由两端至中心逐步减弱;全尺寸试验证实水泥环一界面脱粘形成微环隙,底部气体沿着微环隙上窜导致上部B环空带压,水泥环本体及二界面在各组测试压力下均未出现破坏,不建议现场在现有基础上继续提高储气压力。研究结果可指导H储气库注采参数优化设计,并为国内外类似储气库运行制度的合理制定提供参考。Cyclic injection and production of gas would cause cyclic loads on the cement sheath of gas storage wells,which can easily lead to the sealing failure of cement sheath.In the paper,against the background of sealing failure of cement sheath in H gas storage well,the tests on cyclic loading and unloading,mechanics,porosity and permeability of hardened cement were conducted,the microstructure CT morphology of hardened cement after cyclic loading was obtained,and full-scale cement sheath sealing failure tests were conducted.The experimental results show that after 30 turns of cyclic loading,the mechanical properties of hardened cement decrease and the gas penetrating power increases,but the gas can still be effectively prevented from leaking from the cement matrix;cyclic loading and unloading would cause damage to the microstructure of hardened cement,resulting in cumulative plastic strain,and the more cycles there are,the greater the cumulative plastic strain is;after cyclic loading and unloading,the CT scan morphology of hardened cement shows that there is microstructural damage in the hardened cement,and the degree of microstructural damage gradually weakens from both ends to the center;the full-scale test confirms that the abhesion of hardened cement-inner casing interface forms micro annulus,the bottom gas flows up along the micro annulus,causing pressure in the upper B annulus,but the cement sheath body and the second interface do not show any damage under each group of test pressure,so it is not recommended to continue to increase the gas storage pressure on the existing basis.The study results guide the optimization design of injection and production parameters of H gas storage,and provide reference for the reasonable formulation of operation system of similar gas storages at home and abroad.

关 键 词：储气库井 水泥环 循环载荷 密封失效 全尺寸试验 

分 类 号：TE88[石油与天然气工程—油气储运工程]