Study on Dynamic Behavior of a Titanium Alloy Drill Pipe in Complex Wells

Traditional steel drill pipes can no longer meet the requirements of complex wells with ultradeep, ultrahigh pressure, and long horizontal section; hence, titanium alloy drill pipes are an ideal substitute. This paper explores how titanium drill pipes behave in complex wells. The extrusion and tensile test of titanium alloy pipe was first established. Then, based on the experimental data, the downhole mechanical behavior of a titanium alloy drill pipe was studied from the buckling, contact force, and operating friction with an actual complex well. Meanwhile, the mechanism of friction reduction is analyzed and discussed. The research achievements indicate that the strength of a titanium alloy drill pipe is equal to that of a steel pipe and has good plastic deformation capacity. The titanium alloy drill pipe is more prone to buckling during operation, but it has a smaller contact force, which can effectively reduce the operation friction. It was found that the influent of buckling on slide force was much less than of the gravity and stiffness by mechanism analysis. The research achievements can provide specific theoretical and practical references for the revelation of the mechanical behavior and functional performance of titanium alloy drill pipe in the field operation.