Research On The Torsional Performance Of Aluminum Alloy Drill Pipe

Oil drill pipe is the important equipment for oil and gas exploration and production,a lot of problems exist in conventional steel drill pipe,such as:poor corrosion resistance,over weight of hook load.Aluninum alloy drill pipe(ADP) has the advantages of high specific strength(ultimate breaking strength and relative density ratio),ligth weigth,small friction value with the wall,small bending stress,good resistance of H2S and CO2 corrosion and so on.Therefore ADP has a greater advantage than steel drill pipe in certain well conditions.Domestic ADP reseach starts late,there is no large-scale promotion,reasons mainly are:imperfection of reaserch on material and mechanical properties, weak torsional performance and lack of mature calculation formula,higher assembly requirement and condition of hot assembly.What affects ADP’s torisional performance mostly is primarily the torsional performance of tool joint,this article studies the torsional performance based on the assembly interference value.ADP and common steel drill pipe have significantly different in structure,material and assembly method.This article analyzes the status of ADP at home and abroad,and compares they two from the perspective of the mechanical properties and torsional principle.Combined with the existing method of analysis and calculation,based on the calculation of thick cylinder connection with interference,this article makes analytical calculation of the ADP interference by dividing the pipe into segments.The results make a unity for the formulas with the fewest calculation parameters,and improve the computing operability and usability.Model of the ADP joint is built and analyzed by MSC.MARC.This article comprehensively compares the five parameters of make-up torque,contact pressure,force on each thread,SCF and sealindex,then selects out the optimal interference with best joint’s performance.Results of the simulation is verified through hot assembly test and make-down test.FEA method is used for analysis of the hot assembly,and quantitatively analyzes the temperature and deformation during the assembly process,which has a guiding role for thermal assembly.Results of this study has important guiding significance for the development of ADP especially for the assembly interference study.Method of combining the sample test and FEA will provide useful technical support for the future development and promotion of the ADP.