新疆油田玛湖地区套管损坏机理及主控因素研究  

Investigation of Mechanism and Dominant Factors of Casing Damage in Mahu Area in Xinjiang Oilfield

作　　者：张丽萍[1] 李一强 舒振辉[1] 赵田 王航 韩礼红 ZHANG Liping;LI Yiqiang;SHU Zhenhui;ZHAO Tian;WANG Hang;HAN Lihong(Xinjiang Oilfield Company of PetroChina,Karamay,Xinjiang 834000,China;State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials,CNPC Tubular Goods Research Institute,Xi′an,Shaanxi 710077,China)

机构地区：[1]中国石油天然气股份有限公司新疆油田分公司,新疆克拉玛依834000 [2]中国石油集团工程材料研究院有限公司,石油管材及装备材料服役行为与结构安全国家重点实验室,陕西西安710077

出　　处：《石油管材与仪器》2022年第5期26-31,共6页Petroleum Tubular Goods & Instruments

基　　金：国家自然科学基金面上项目“稠油热采井次生硫化氢环境下套管柱应变设计关键参量预测方法研究”(编号:52074346);新疆油田公司科研项目“新疆玛湖地区水平井套管选用优化及技术规范研究”(编号:2019-QT-37)。

摘　　要：玛湖地区是新疆油田新发现的10亿吨级储量油田,也是增储上产的主力区块。自开发以来套管损坏时有发生,严重影响了玛湖油田的正常开发。现场调研表明:套管损坏的主要模式包括钻井下套管过程接头螺纹断裂、连续管酸化压裂过程接箍纵向开裂及分段体积压裂过程套管变形。接头螺纹断口和现场下井记录表明:玛湖地区大三维、小间隙井身结构引起下井套管遇阻,反复多次上提-下放造成接头螺纹疲劳断裂。接箍开裂特征及能谱分析表明:连续油管压裂和环空腐蚀介质共同作用引起接箍应力腐蚀开裂。水敏性和三轴加载试验证实:吸水膨胀的岩石蠕变诱发地层滑移,剪切及非均匀外挤载荷导致套管变形。从套管损坏的主控因素角度,提出了套管安全服役技术条件。建议从接头扣型优选、接箍材料适用性评价及井筒一体化协调变形方面,解决玛湖地区复杂多样的套管损坏问题。A new oilfield with 1 billion tons reserves had been uncovered in Mahu area of Xinjiang oilfield,which is regarded as the main block for increasing reserve and production in future.Casing damage occurred continuously and influenced regular production since oilfield development.Field investigation showed that there were three types of failure mode,including thread fracture of casing connection during running casing into downhole,longitudinal cracking of coupling during acidizing and fracturing and casing deformation during staged volume fracturing.Fractographic observations and operation records revealed that low cycle fatigue was dominant fracture mechanism for thread fracture,which resulted from upright and down repeatedly due to well profile design with big three-dimension and small gap.Fractographic feature and energy disperse spectrum(EDS)indicated that longitudinal cracking of coupling could be attributed to stress corrosion,with evidence of fracturing using coiled tubular and corrosion medium in annular.In addition,experimental results including both water sensitivity and triaxial loading tests demonstrated that rock absorbed water and expanded in corresponding well section,then caused formation sliding,which finally resulted in casing deformation.The technical requirement was proposed for security service evaluation of casing from the viewpoint of key factor for casing damage.Finally,it is suggested to prevent casing damage via optimization selection of connection type,fitness for service evaluation of coupling material and integratedly coordinating deformation of well.

关 键 词：玛湖地区 套管损坏 下套管作业 酸化压裂 分段压裂 

分 类 号：TE931.2[石油与天然气工程—石油机械设备]