基于ABAQUS显示动力学的柔性钻具水平钻进动力学特性分析

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。该技术使用了柔性化设计的套管磨铣开窗、超短半径造斜和水平稳斜钻具，分别应用于套管开窗、造斜和水平钻进3个工序。柔性钻具可通过钻杆、修井管柱或连续管起下钻，钻出曲率半径为 1.5～5.0m 的造斜段和 40～60m 长的水平段。由于其超短半径造斜特性，可在同一薄地层内完成开窗、造斜和水平段钻进工序，而水平段井眼轨迹的垂直偏移直接影响靶点钻遇率。

柔性钻具技术应用始于国外，1986年，美国EastmanChristensen公司[1]于密歇根州白云岩储层钻成水平段长为 58.8m 的柔性钻具分支井眼，单井日产油约 。我国于2017年在吉林油田实现了曲率半径为 1.8m 、水平钻进距离 80.1m 的柔性钻具径向井，措施后产量提高3倍以上[2]；2020年在海上油田实现了曲率半径为 3m 、造斜率为每米16^∘ 的4分支超短半径柔性钻具钻井作业[3]；2021年中国石油大学（北京）在江汉油田陵72-5CZ井首次提出连续管配合柔性钻具侧钻的思路，并开展了现场试验[4]。

在柔性钻井理论研究方面，LUOM.等将三维梁单元、万向节单元、刚性梁单元、梁-梁接触单元相结合，建立了井筒内柔性钻具双层接触非线性有限元模型并采用动态松弛法进行数值求解；LIUH.等[6-7提出了一种基于万向节设计的柔性单元超短半径取芯技术；MINGE.等[8]介绍了一种改进超短半径径向井柔性钻具的方法；杨永印等建立了超短半径水平井技术匹配的小钻杆有限元模型；……