氮气钻井井底岩爆机理及动态过程演化  

Mechanism and dynamic process evolution of bottomhole rock burst in nitrogen drilling

作　　者：罗成波[1] 孟英峰[1] 李皋[1] 刘厚彬[1] 杨旭[1] 林楠 Luo Chengbo;Meng Yingfeng;Li Gao;Liu Houbin;Yang Xu;Lin Nan(State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation//Southwest Petroleum University,Chengdu,Sichuan 610500,China;Bazhou Drilling Company,CNPC Xibu Drilling Engineering Co.,Ltd.,Bazhou,Xinjiang 841000,China)

机构地区：[1]“油气藏地质及开发工程”国家重点实验室·西南石油大学 [2]中国石油西部钻探工程公司巴州钻井公司

出　　处：《天然气工业》2019年第7期99-105,共7页Natural Gas Industry

基　　金：国家自然科学基金重点项目“气体钻井技术基础研究”(编号:51134004)

摘　　要：氮气钻井钻遇致密砂岩裂缝圈闭高压导致井底岩爆是QL1井恶性井喷事故的根本原因,针对岩爆机理进行系统分析并形成正确的认识是恢复气体钻井技术良性发展的紧迫需要。为此,通过分析井底岩石性质、计算井底岩石裂缝面应力,利用常规井壁失稳分析方法研究井底岩爆机理;在此基础上,借助Visual Basic语言和Matlab软件编程,进行了岩爆的动态演化模拟,分析判断QL1井录井监测参数的异常变化。研究结果表明:当井底逐渐接近裂缝圈闭高压的过程中,裂缝面周向应力和径向应力差值逐渐增大,主应力之间的差值所引起的剪应力的增长使裂缝面产生压剪破坏以及压剪和拉伸复合破坏模式,直至破坏区连通井筒,高压气体携带大量碎屑喷入井内,释放大量能量,产生井底岩爆,上顶压缩钻具。结论认为,该研究成果系统地解释了QL1井录井监测参数的异常变化,其分析方法可以为井底岩爆的防治提供理论基础。Bottomhole rock burst caused by fracture trap high pressure in tight sandstone during nitrogen drilling is the root cause of the vicious blowout accident in Well QL1. In order to restore the sound development of gas drilling technology, it is in an urgent need to analyze the mechanisms of rock burst systematically and establish the accurate understanding. In this paper, the mechanisms of bottomhole rock burst were studied using conventional wellbore instability analysis methods after the properties of the rocks at the bottomhole were analyzed and the fracture plane stress of the rocks at the bottomhole was calculated. Then, the dynamic evolution of rock burst was simulated with the help of Visual Basic language and Matlab software programming. Finally, abnormal change of logging monitoring parameters of Well QL1 was analyzed. And it is indicated that as the bottomhole gradually approaches the fracture trap high pressure, the difference value between circumferential stress of surface plane and radial stress increases gradually;and that the increase of shear stress caused by the difference value of the principal stresses leads to shear failure or tension failure at the fracture plane until the failure zone is connected with the wellbore, then high pressure gas swarms into the wellbore with a lot of rock debris, releasing a large amount of energy, and consequently bottomhole rock burst happens and displaces upward to compress the drilling tools. In conclusion, the research results systematically explain the abnormal change of logging monitoring parameters of Well QL1 and the analysis methods provide a theoretical basis for bottomhole rock burst prevention and control .

关 键 词：氮气钻井 有效应力 缝圈闭高压 弹塑性井底应力 井底岩爆 

分 类 号：TE242[石油与天然气工程—油气井工程]