Research On Performance Of TC27 Titanium Alloy Drill Pipe Based On Deep Sea Drilling

With the development of oil and gas fields gradually moving toward deep sea,ultra-deep sea,and offshore oil that strongly corroded environment,the demand for new types of drill pipe in the oil drilling field is increasingly urgent.The titanium alloy material stands out with its outstanding properties.Therefore,the investigation and application of titanium alloy drill pipe in deep sea oil and gas fields,the status quo of research on the corrosion mechanical properties of materials,and the development status of drill pipe vibration theory are carried out.Using the test method,through the steps of material selection,material processing and test method design,the tensile test of the new material TC27 titanium alloy and the corrosion test under H₂S/CO₂ environment were carried out,and the engineering stress-strain curve and stress corrosion were obtained.The results show that the TC27 titanium alloy material has low density,high specific strength,and high tensile strength,and has good corrosion resistance.Based on the theory of material mechanics and vibration mechanics,the natural frequency distribution equations of the longitudinal,lateral and torsional vibrations of the TC27 titanium alloy drill pipe that with or without fluid damping are deduced respectively,and the frequency distribution equations of the two cases were calculated and compared by using MATLAB programming method.The results show that the three vibration frequencies of TC27 titanium alloy drill pipe are reduced by the fluid damping effect.Using ANSYS software,PIPE59 unit is used to model the 2120m TC27 titanium alloy drill pipe,and the influence of different TC27titanium alloy drill pipe size on natural frequency of drill pipe longitudinal vibration is simulated.It was found that the natural frequency of each order of longitudinal vibration is basically constant.The effect of the length variation of the drill stem of different TC27titanium alloys on the natural frequency of the transverse vibration was simulated.It is found that the longer the drill rod length,the lower the natural frequency.The torsional vibration of the different drill collar length proportion of the drill pipe is simulated.The smaller drill collar length proportion,the lower natural frequency of the torsion vibration except the first-order.By selecting the dynamic harmonics response of the different nodes,it is shown that the TC27 titanium alloy drill rod has the largest amplitude change at the natural frequency between all three vibration modes and may cause the greatest damage.The K_ISSCC?stress intensity factor critical value?of the TC27 titanium alloy material obtained by combining the depth of the model node and the stress corrosion test is calculated according to the actual operating conditions to obtain the corrosion fatigue life of the material.