异形PDC切削齿破碎塑性泥岩热固耦合数值模拟研究  

Thermal solid coupling numerical simulation of plastic mudstone fractured by special PDC cutting teeth

作　　者：罗鸣 高德利[1] 李文拓 LUO Ming;GAO Deli;LI Wentuo(MOE Key Laboratory of Petroleum Engineering,China University of Petroleum,Beijing,Beijing 102249,China;CNOOC China Limited,Hainan Branch,Haikou,Hainan 570312,China)

机构地区：[1]中国石油大学(北京)石油工程教育部重点实验室,北京102249 [2]中海石油(中国)有限公司海南分公司,海南海口570312

出　　处：《中国海上油气》2023年第2期129-137,共9页China Offshore Oil and Gas

基　　金：国家自然科学基金重点项目“复杂结构‘井工厂’立体设计建设基础研究(编号:52234002)”;中海石油(中国)有限公司项目“南海西部油田上产2000万方钻完井关键技术研究(编号:CNOOC-KJ135ZDXM38ZJ05ZJ)”部分研究成果。

摘　　要：中国南海莺琼盆地存在大量高温高压塑性泥岩地层,面临PDC钻齿难以吃入岩层、钻井速度慢的难题,开展该岩层破岩机理研究对于提高钻井速度有重要意义。本文通过离散单元法建立了由平行粘结颗粒组成的岩样二维、三维热固耦合数值模型,并标定了模型细观参数,开展了不同温度下圆柱形齿、楔形齿、屋脊齿和尖圆齿切削塑性泥岩的数值模拟研究。研究结果表明:随着楔形齿侵入时间增加,泥岩损伤区域增大,且径向裂纹向下扩展一定范围后停止扩展,岩石表现为塑性破碎;温度升高对楔形齿侵入岩石产生的径向裂纹和侧向裂纹扩展具有抑制作用;高温环境下,尖圆齿破岩效果明显好于屋脊齿和圆柱齿。现场应用结果表明,相同工况下尖圆齿PDC钻头机械钻速明显高于邻井圆柱齿PDC钻头,与数值模拟结果一致。本文研究成果可为南海高温高压储层破岩提速钻头优化提供理论依据。There are a large number of high-temperature and high-pressure plastic mudstone formations in the Yingqiong basin in South China Sea.It is difficult for the PDC bit to feed into the strata and the drilling speed is slow.Therefore,studying the rock fracturing mechanism of this rock formation is of great importance for improving drilling speed.In this paper,the two-dimensional and three-dimensional thermal solid coupling numerical models of rock samples composed of parallel cohesive particles are established by discrete element method,and the microscopic parameters of the models are calibrated.The numerical simulation of plastic mudstone fractured by cylindrical teeth,wedge teeth,ridge teeth,and sharp circular teeth is carried out at different temperatures.It is revealed by the simulation that the damage area of mudstone increases with the increase of wedge teeth invasion time,and the radial crack stops expanding after extending downward to a certain range,resulting in plastic fracture of rock.Meanwhile,the temperature increase inhibits the propagation of radial and lateral cracks caused by wedge teeth invading rock.Under high temperature environment,the rock fracturing effect of sharp circular teeth is significantly better than that of ridge teeth and cylindrical teeth.The field application results show that the mechanical penetration rate of the PDC bit with sharp circular teeth is significantly higher than that of the PDC bit with cylindrical teeth in adjacent wells under the same operating conditions,which is consistent with the numerical simulation results.The research results in this paper can provide a theoretical basis for rock fracturing speed improvement and drill bit optimization in high-temperature and high-pressure reservoirs in the South China Sea.

关 键 词：离散元法 热固耦合 异形齿 岩石破碎 塑性泥岩 

分 类 号：TE21[石油与天然气工程—油气井工程]