摘要
煤层多弱面结构会导致井眼力学稳定性更差,在钻井过程中极易发生掉块垮塌。为研究煤层井壁坍塌规律,文章基于MG-C和岩石弱面双准则建立了考虑地层产状、井眼轨迹和煤层多弱面的坍塌压力计算模型,分析了煤层多弱面对坍塌压力影响的主控因素和影响规律,并针对含砂岩和煤层的非连续煤夹层进行坍塌压力实例计算。结果表明:随着井斜角增大,影响坍塌压力的主控因素由割理面转变为层理和本体;当井眼方位与割理面互成约45°夹角时,割理面为主控因素;综合来看煤层多弱面结构对坍塌压力的影响更大,且以沿弱面发生破坏为主;随着层理倾角的增大,坍塌压力先增大后减小,在层理倾角约45°时坍塌风险最大;随着层理倾向增大,主要影响坍塌方位,对数值大小影响不大。文章研究成果可为含煤夹层在钻井过程中预防井壁垮塌提供更好的理论指导。
The multi-weakness plane structure of coal seam will lead to poor borehole visual stability,and the wellbore wall of the coal seam section is prone to collapse and drop blocks during drilling process.In order to study the law of coal seam wellbore wall collapse,this paper established a collapse pressure calculation model based on the MG-C criterion and the rock weak plane criterion considering the formation occurrence,wellbore trajectory and multiple weak planes of the coal seam,and analyzed the main controlling factors and law of the influence of the weak plane of the coal seam on the collapse pressure,and the case calculation of collapse pressure is carried out for discontinuous coal interlayers containing sandstone and coal seams.The results show that with the increase of the well inclination angle,the main controlling factor affecting the collapse pressure changes from the cleat plane to the bedding and the body.When the wellbore orientation and the cleat plane form an included angle of about 45°,the cleat plane is the main controlling factor,from a comprehensive point of view,the multi-weak plane structure of the coal seam has a greater impact on the collapse pressure,and the main failure occurs along the weak plane;with the increase of the bedding dip angle,the collapse pressure first increases and then decreases,and the collapse risk is greatest when the inclination angle is about 45°.As the inclination of the stratum increases,it mainly affects the collapse orientation,but has little effect on the numerical value.The research in this paper can provide better theoretical guidance for the prevention of shaft wall collapse in the drilling of coal-bearing interlayer.
作者
唐川富
李忠慧
陈晗
幸雪松
寿翔
胡棚杰
TANG Chuanfu;LI Zhonghui;CHEN Han;XING Xuesong;SHOU Xiang;HU Pengjie(School of Petroleum Engineering,Yangtze University,Wuhan,Hubei 430100,China;Hubei Provincial Key Laboratory of Oil and Gas Drilling and Production Engineering,Wuhan,Hubei 430100,China;Chuanqing Drilling Engineering Co.,LTD.Guanghan,Sichuan 618300,P.R.China;CNOOC Research Institute Co.,LTD.,Beijing 100028,China;Chengdu Best Diamond Bit Co.,LTD.,Chengdu,Sichuan 610041,China)
出处
《钻采工艺》
CAS
北大核心
2022年第5期8-15,共8页
Drilling & Production Technology
基金
国家自然科学基金项目“深水高温高压环境下钻井全过程井壁稳定评价方法”(编号:51774050)。
关键词
煤夹层
多弱面结构
坍塌压力
破坏准则
割理面
地层倾角
安全窗口
coal interlayer
multi-weakness plane
collapse pressure
failure criterion
cleat plane
inclination angle
safety window
