摘要
底部钻具组合(BHA)在井下长期剧烈振动容易导致其疲劳失效,但目前多数研究均通过微分方程计算BHA疲劳寿命,与现场实际工况差距较大。为了更准确地预测BHA的疲劳寿命,借助以有限元法为基础的钻柱动力学理论,考虑钻柱初始裂纹缺陷,建立了基于钻柱动力学的底部钻具组合疲劳寿命预测模型,利用Newmark-β法对动力学模型进行求解,并与其他文献的研究结果进行对比,验证了模型的准确性;研究了钻压、转速、初始裂纹深度及稳定器安装位置等关键参数对底部钻具组合疲劳寿命的影响规律。研究结果表明:BHA横向振动比纵向振动更大,横向振动是BHA疲劳失效的主要原因;越靠近钻头横向振动越大,所以近钻头处BHA疲劳寿命更短;钻压越大,中和点下部BHA疲劳寿命缩短越显著;转速越大BHA疲劳寿命越短,低转速范围内转速对BHA疲劳寿命影响较小,高转速范围内转速对BHA疲劳寿命影响较大;具有更大初始裂纹深度的BHA,其疲劳寿命会更短;安装稳定器可以延长近钻头处BHA的疲劳寿命,算例中稳定器安装在距离钻头9 m的位置最佳。研究成果可为优选钻井参数以及确保钻柱安全提供一定的理论指导。
The bottom hole assembly(BHA)is prone to fatigue failure due to long-term severe vibration in the wellbore.Most studies use the differential equation to calculate the fatigue life of BHA,which has a large difference from the actual working conditions on site.In order to more accurately predict the fatigue life of BHA,with the help of the finite element method based drill string dynamics theory,and considering the initial crack defect of drill string,a fatigue life prediction model of BHA based on drill string dynamics was built,the Newmark-βmethod was used to solve the dynamic model,and the accuracy of the model was verified by comparing the results with those in other references.Moreover,the influences of key parameters such as weight on bit(WOB),rotary speed,initial crack size and stabilizer installation position on the fatigue life of BHA were analyzed.The study results show that the transverse vibration of BHA is larger than the longitudinal vibration,and the transverse vibration is the main reason for the fatigue failure of BHA.The closer to the bit,the greater the transverse vibration is;so,the fatigue life of BHA near the bit is shorter.The larger the WOB,the more obvious the reduction of the fatigue life of BHA at the lower neutral point is.The larger the rotary speed,the shorter the fatigue life of BHA is.In the low rotary speed range,the rotary speed has little effect on the fatigue life of BHA;in the high rotary speed range,the rotary speed has great effect on the fatigue life of BHA.The larger the initial crack size on BHA,the shorter the fatigue life of BHA is.The installation of stabilizer can prolong the fatigue life of BHA near the bit.In the example,the effect is the best when the stabilizer is installed at the position of 9 m from the bit.The study results provide certain theoretical guidance for optimizing drilling parameters and ensuring drill string safety.
作者
毛良杰
甘伦科
幸雪松
李隽
Mao Liangjie;Gan Lunke;Xing Xuesong;Li Juan(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation,Southwest Petroleum University;Beijing Research Center,CNOOC Limited;PetroChina Research Institute of Petroleum Exploration&Development)
出处
《石油机械》
北大核心
2022年第9期1-9,共9页
China Petroleum Machinery
基金
国家重点研发计划资助项目“深海水合物开采立管水动力载荷分析和甲烷气体演化风险监测技术研究”(2019YFC0312303)
中国石油-西南石油大学创新联合体科技合作项目(2020CX040204)
中国石油科技创新基金资助项目“天然气水合物开采立管动力特性及安全控制技术研究”(2020D-5007-0210)
四川省重点研发项目“复杂构造背景深层页岩气储层地应力场分析关键技术研究与应用”(21ZDYF3109)、“川渝地区复杂地层页岩气勘探开发高效钻井关键技术研究”(21SYSX0054)联合资助
中海油项目“文昌油田群井壁稳定性及安全钻井工艺研究”(CCL2022RCPS0139PSN)。
