Double shoulder drill pipe joint(DSJ)is a novel thread structure which appears in recent years.Its strength reduced efficiently while the structure design is not appropriately,for the DSJ’s mechanical behaviors weren...Double shoulder drill pipe joint(DSJ)is a novel thread structure which appears in recent years.Its strength reduced efficiently while the structure design is not appropriately,for the DSJ’s mechanical behaviors weren’t well studied.In this paper a 3D whole structure finite element model of DSJ was established based on the Principle of Virtual Work,and validated the model’s computing results by experimental results.The authors analyzed the stress and strain distribution with the 3D whole structure finite element model’s computing results under torque moment,compression force,tension load,and bend moment.And then acquired the DSJ’s mechanical behaviors under each load.The research works of this paper refer accordance to recognize and design the DSJ.展开更多
Based on the three-dimensional elastic-plastic finite element analysis of the 8"(203.2 mm)drill collar joint,this paper studies the mechanical characteristics of the pin and box of NC56 drill collar joints under ...Based on the three-dimensional elastic-plastic finite element analysis of the 8"(203.2 mm)drill collar joint,this paper studies the mechanical characteristics of the pin and box of NC56 drill collar joints under complex load conditions,as well as the downhole secondary makeup features,and calculates the downhole equivalent impact torque with the relative offset at the shoulder of internal and external threads.On the basis of verifying the correctness of the calculation results by using measured results in Well GT1,the prediction model of the downhole equivalent impact torque is formed and applied in the first extra-deep well with a depth over 10000 m in China(Well SDTK1).The results indicate that under complex loads,the stress distribution in drill collar joints is uneven,with relatively higher von Mises stress at the shoulder and the threads close to the shoulder.For 203.2 mm drill collar joints pre-tightened according to the make-up torque recommended by American Petroleum Institute standards,when the downhole equivalent impact torque exceeds 65 kN·m,the preload balance of the joint is disrupted,leading to secondary make-up of the joint.As the downhole equivalent impact torque increases,the relative offset at the shoulder of internal and external threads increases.The calculation results reveal that there exists significant downhole impact torque in Well SDTK1 with complex loading environment.It is necessary to use double shoulder collar joints to improve the impact torque resistance of the joint or optimize the operating parameters to reduce the downhole impact torque,and effectively prevent drilling tool failure.展开更多
API standard threads are the most commonly used thread configurations for drill pipe joints in the petroleum industry.Recently with the increasing application of horizontal wells and extended-reach wells in drilling e...API standard threads are the most commonly used thread configurations for drill pipe joints in the petroleum industry.Recently with the increasing application of horizontal wells and extended-reach wells in drilling engineering,drill pipe joint threads are subjected to complex loads,and drill pipe joint thread breakage accidents occur frequently.The API NC38 threaded pair used in the SU36-8-4H2 well suffered a fracture accident.Macroscopic analysis found that the fracture sites were located near the root of the first engagement pin-thread where the stress was greatest.Therefore,it is necessary to find an alternative method to reduce the largest stress of NC38 threads.Then,a new design method of unequal taper thread(UTT)pairs is proposed that the taper of pin thread,slightly smaller than the taper of matched-box thread,is not equal to one of box-thread.In the UTT pairs of API NC38 thread,the taper of box thread is kept as the standard taper of 1:6,but the taper of pin thread is,respectively,1:6.1(UTT-I),1:6.2(UTT-Ⅱ),1:6.3(UTT-Ⅲ)and 1:6.4(UTT-IV).The 3D finite element models of four UTT pairs and one standard pair based on NC38 thread were developed,and the mechanical properties of five thread pairs bearing such typical working loads as torque,axial compression,axial tension,bending moment,internal and external pressure,were analyzed.The results show that four UTT pairs are superior to the standard pair of API NC38,and UTT-Ⅲ has the most performance in all of four UTT pairs.Compared with the standard pair of API NC38,UTT-Ⅲ pair can improve the bearing capacity such as torsion strength,compression strength,tensile strength,bending strength,strength against internal and external pressure,by 24.8%,13.2%,22%,9.99%and 14.2%,respectively.The new design method of UTT pair enhances the bearing capacity of API NC38 thread,and has been applied in Changqing Drilling Company of CNPC Chuanqing Drilling Engineering Company Limited.The UTT-thread pair method is not only applicable for API series threads to improve the con展开更多
基金This research is supported by Scientific Research Starting Project of SWPU(No.2017QHZ012)Major Project by Education Office of Sichuan Province(No.17ZA0418)+1 种基金supported by the Natural Science Fund for Outstanding Youth Science Fund(Grant No.51222406)Scientific Research Innovation Team Project of Sichuan Colleges and Universities(2017TD0014).
文摘Double shoulder drill pipe joint(DSJ)is a novel thread structure which appears in recent years.Its strength reduced efficiently while the structure design is not appropriately,for the DSJ’s mechanical behaviors weren’t well studied.In this paper a 3D whole structure finite element model of DSJ was established based on the Principle of Virtual Work,and validated the model’s computing results by experimental results.The authors analyzed the stress and strain distribution with the 3D whole structure finite element model’s computing results under torque moment,compression force,tension load,and bend moment.And then acquired the DSJ’s mechanical behaviors under each load.The research works of this paper refer accordance to recognize and design the DSJ.
基金Supported by the National Natural Science Foundation of China(52174003,52374008).
文摘Based on the three-dimensional elastic-plastic finite element analysis of the 8"(203.2 mm)drill collar joint,this paper studies the mechanical characteristics of the pin and box of NC56 drill collar joints under complex load conditions,as well as the downhole secondary makeup features,and calculates the downhole equivalent impact torque with the relative offset at the shoulder of internal and external threads.On the basis of verifying the correctness of the calculation results by using measured results in Well GT1,the prediction model of the downhole equivalent impact torque is formed and applied in the first extra-deep well with a depth over 10000 m in China(Well SDTK1).The results indicate that under complex loads,the stress distribution in drill collar joints is uneven,with relatively higher von Mises stress at the shoulder and the threads close to the shoulder.For 203.2 mm drill collar joints pre-tightened according to the make-up torque recommended by American Petroleum Institute standards,when the downhole equivalent impact torque exceeds 65 kN·m,the preload balance of the joint is disrupted,leading to secondary make-up of the joint.As the downhole equivalent impact torque increases,the relative offset at the shoulder of internal and external threads increases.The calculation results reveal that there exists significant downhole impact torque in Well SDTK1 with complex loading environment.It is necessary to use double shoulder collar joints to improve the impact torque resistance of the joint or optimize the operating parameters to reduce the downhole impact torque,and effectively prevent drilling tool failure.
基金the financial support from the Open Foundation of Cooperative Innovation Center of Unconventional Oil and Gas,Yangtze University(Ministry of Education of China&Hubei Province),(No.UOGBX2022-05,UOG2022-26 and UOGBX2022-04)the National Natural Science Foundation of China(No.51974035,U1262108 and U1762214)the key R&D program of Hubei Province(No.2020BAB055).
文摘API standard threads are the most commonly used thread configurations for drill pipe joints in the petroleum industry.Recently with the increasing application of horizontal wells and extended-reach wells in drilling engineering,drill pipe joint threads are subjected to complex loads,and drill pipe joint thread breakage accidents occur frequently.The API NC38 threaded pair used in the SU36-8-4H2 well suffered a fracture accident.Macroscopic analysis found that the fracture sites were located near the root of the first engagement pin-thread where the stress was greatest.Therefore,it is necessary to find an alternative method to reduce the largest stress of NC38 threads.Then,a new design method of unequal taper thread(UTT)pairs is proposed that the taper of pin thread,slightly smaller than the taper of matched-box thread,is not equal to one of box-thread.In the UTT pairs of API NC38 thread,the taper of box thread is kept as the standard taper of 1:6,but the taper of pin thread is,respectively,1:6.1(UTT-I),1:6.2(UTT-Ⅱ),1:6.3(UTT-Ⅲ)and 1:6.4(UTT-IV).The 3D finite element models of four UTT pairs and one standard pair based on NC38 thread were developed,and the mechanical properties of five thread pairs bearing such typical working loads as torque,axial compression,axial tension,bending moment,internal and external pressure,were analyzed.The results show that four UTT pairs are superior to the standard pair of API NC38,and UTT-Ⅲ has the most performance in all of four UTT pairs.Compared with the standard pair of API NC38,UTT-Ⅲ pair can improve the bearing capacity such as torsion strength,compression strength,tensile strength,bending strength,strength against internal and external pressure,by 24.8%,13.2%,22%,9.99%and 14.2%,respectively.The new design method of UTT pair enhances the bearing capacity of API NC38 thread,and has been applied in Changqing Drilling Company of CNPC Chuanqing Drilling Engineering Company Limited.The UTT-thread pair method is not only applicable for API series threads to improve the con
