页岩气多级压裂井筒完整性失效机理及控制方法研究进展  

Research Progress on Failure Mechanism and Control Methods of Wellbore Integrity During Multi-stage Fracturing of Shale Gas

作　　者：李军 丁士东[2] 韩礼红 陶谦[2] LI Jun;DING Shidong;HAN Lihong;TAO Qian(China University of Petroleum-Beijing at Karamay,Karamay,Xinjiang 834000,China;Sinopec Research Institute of Petroleum Engineering,Beijing 100101,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]中国石油大学(北京)克拉玛依校区,新疆克拉玛依834000 [2]中国石化石油工程技术研究院,北京100101 [3]中国石油集团石油管工程技术研究院,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》2020年第4期10-15,共6页Petroleum Tubular Goods & Instruments

基　　金：国家自然科学基金-石油化工联合基金重点支持项目“页岩气水平井井筒完整性失效机理与控制方法研究”(项目编号:U1762211);企业创新发展联合基金-集成项目“海相深层油气富集机理与关键工程技术基础研究-构造应力集中区页岩气井套管载荷模型及结构完整性失效机理”(项目编号:U19B6003-05-04-02)。

摘　　要：综述了国内外页岩气多级分段压裂过程中井筒完整性失效的概况。总体来看,我国的页岩气井筒完整性失效问题明显比国外严重,严重制约了我国页岩气的高效开发。进一步明确了失效形式分为两大类,一是结构完整性失效,即套管产生变形;二是密封完整性失效,即出现环空带压现象。分析了页岩气井筒完整性失效机理,包括压裂前的井筒组合体原始应力状态、压裂过程中套管载荷的动态变化等多个阶段。分析表明,复杂的地应力条件、地层各向异性、长水平段非均质性、岩性界面、断层和裂缝发育、井眼轨迹质量差、下套管困难等对压裂前套管的原始应力有明显影响。而在压裂过程中,套管承受拉压交变载荷、近井地应力场及地层性质动态变化、裂缝非均匀扩展、微断层滑移、套管温度的急剧变化、水泥环出现微环隙或微裂隙等是导致井筒完整性失效的原因。对中国页岩气套管变形问题而言,以地层滑移的影响最为显著。最后提出了井筒完整性控制方法,包括:井眼轨道优化与轨迹控制、套管钢级与壁厚优选、固井方式优化、水泥浆体系优化、分段分簇及压裂参数优化、采用可溶桥塞、井身结构优化、裸眼分段压裂等,可为我国页岩气井筒完整性失效问题的治理提供参考。An overview of wellbore integrity failure during the multi-stage fracturing process of shale gas at home and abroad is summarized in this paper.Overall,the problem of shale gas wellbore integrity failure in China is obviously more serious than that abroad,which seriously restricts the high efficiency of shale gas development.It is further clarified that the failure modes are divided into two categories.One is structural integrity failure,that is,the casing deformation.The other is seal integrity failure,that is,the sustained casing pressure.The failure mechanism of shale gas wellbore integrity was analyzed,including the initial stress state of the wellbore assembly before fracturing and the dynamic changes of casing load during fracturing.The analysis result shows that complex in-situ stress conditions,formation anisotropy,long horizontal section heterogeneity,lithologic interface,fault and fracture development,poor borehole trajectory quality and the difficulty of running casing have a significant effect on the original stress of casing before fracturing.During the fracturing process,the casing is subjected to tensile and compression alternating loads,near-well in-situ stress field and dynamic changes of formation properties,non-uniform propagation of cracks,micro-fault slips,sharp changes in casing temperature,and micro annulus in the cement ring or micro-fractures,which are the causes of the failure of the wellbore integrity.For the shale gas casing deformation problem in China,the effect of formation slip is the most significant.Finally,the wellbore integrity control methods are proposed including wellbore trajectory optimization and trajectory control,casing steel grade and wall thickness optimization,cementing method optimization,cement slurry system optimization,segment clustering and fracturing parameter optimization,soluble bridge plugs aplication,wellbore structure optimization,open-hole staged fracturing,etc.,which can provide a reference for the treatment of shale gas wellbore integrity failure in our

关 键 词：页岩气 井筒完整性 套管变形 环空带压 控制方法 

分 类 号：TE931.2[石油与天然气工程—石油机械设备]