基于ABAQUS显示动力学的柔性钻具水平钻进动力学特性分析
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DynamicCharacteristicsofHorizontalDrillingwithFlexible Drill StringBased on ABAQUS ExplicitDynamics
Liu XinHuang ZhongweiWu Xiaoguang LiGenshengShi HuaizhongWang JiaruiWang Minghao （StateKeyLaboratoryofPetroleumResources andEngineering，China UniversityofPetroleum-Beijing）
Abstract：During thedrilingofultrashort-radiusradial horizontal well with flexibledrill string，the vertical shift of wellbore trajectoryaffects the encounteringrateoftarget points.To revealthedynamic characteristicsof horizontal drilling with flexibledrillstringandreduce the vertical shiftofwellboretrajectory，ahorizontaldrilling model offlexibledrillstring was built based onABAQUS explicit dynamics and calculations were carried out subsequently. Theresearch focuses on the motion offlexible drilling string，bit atitude，rock breaking characteristics，trajectory deviationcharacteristics，formationadaptabilityandthesensitivityof trajectory andovercut to weightonbit（WOB）. Theresearch resultsshowthattheprocessof driling with flexibledrillstring exhibits aspiral motion posture，rotating around the borehole axis while rotating around itsown axis.The bit breaks rocks in anapproximately conical scanning posture，andtheprocessofbreaking rocks hasasymmetry.Thefield testverifies theaccuracyofthemodel， andthe rajectorydeviationofflexibledrillstring mainlyoccurs in the gravitydirection，explainingthereason forthe vertical trajectorydeviation inthefieldtest.Thecorrespondingtrajectorydeviationrates insoft，mediumand hard rocksare 4.44% ， 3.71% and 3.52% respectively，and are higher underhigh WOB conditions.Anincrease in WOB reduces the bit lateral aggressivityand overcut，and the preferred WOB for horizontal drilling is （30±5）kN. The research results provide a feasible solution to the study of the motion of flexible drill string.
Keywords：horizontal well；flexibledrill string；trajectory deviation；ultrashort-radius；explicit dynamics： numerical simulation
0 引言
柔性钻具超短半径径向水平井技术是一种侧钻技术，其能够在垂直井眼内的数个地层中钻出多个水平分支，可穿透近井污染带，极大地增加泄流半径。（剩余12430字）