摘要
气体钻井具有自身特点,气体钻井钻具受高速流体冲蚀作用,钻具磨损严重,空气锤反馈的冲击波使钻具接头螺纹容易断裂,气体钻井钻具频繁失效进而影响钻进速度,增加钻井成本。基于岩石力学和气固两项流理论,对气体钻井钻具受流体冲蚀进行分析,建立了环空混合物返速模型,实例计算回压对环空返速的影响。为避免钻具受高速流体冲蚀,应使环空混合物返速介于最小携岩速度和临界冲蚀速度之间。基于力学理论,提出增大井口回压的方法,推导出钻具接头螺纹在预紧力作用下的变形协调方程,应用有限元对钻具螺纹进行应力分析,找出钻具螺纹接头各螺纹牙载荷的分布规律,得出螺纹应力集中区,给出预防钻具失效提高螺纹强度的措施。
Because of Gas drilling’s distinguishing feature, drilling tool is wornouted seriously by high velocity liquid’s erosive action and drilling tool substitute thread is cracked easily by air hammaer upward’s shock wave, all of which impact drilling speed and increase drilling cost. Based on the theory of rock mechanics and gas/ solid two -phase flow, drilling tool erosived by liquid in gas drilling is analysed, return velocity model of mixture in annular is established, return velocity in annular impacted by back pressure is calculated with illustration. In order to avert erosiving by high velocity, return velocity of mixture in annular has to be between minimal carrier velocity and interface erosive velocity. Increasing well head back pressure could decreased the drill tool’s erosiving. Based on mechanical theory,the deformation harmonization equation of drilling tool substitute thread under the influence of pretightening load is fetched. The stress of drilling tool thread is analysed by finite element. The screw thread load distribution regular pattern of drilling tool substitute thread is found out. The thread stress centralized area is obtained, which could provide measure to prevent drilling tool failure and to enhance thread strength.
作者
刘美玲
Liu Meiling(Production Engineering Research Institute of Daqing Oilfield Co.,Ltd.,Daqing Heilongjiang 163453,China)
出处
《辽宁石油化工大学学报》
CAS
2019年第2期59-62,共4页
Journal of Liaoning Petrochemical University
基金
国家科技重大专项"碳酸岩
火成岩及酸性气藏高效安全钻完井技术"(2008ZX05021-002)
关键词
钻具失效
冲蚀
环空返速
有限元分析
螺纹应力
Drilling tool failure
Erosive
Annular return velocity
Finite element analysis
Thread stress
