Integrating Superficially Treated 2024 Aluminum Alloy in Steel Drill String to Deal with Fatigue Problem in Crooked Trajectory for Vertical Deep Well

Abstract

Drilling deep HPHT wells is the most compelling reason for drilling companies to look for alternative drill pipes that meet their requirements. Currently, with the emergence of drill pipes made of materials other than steel, a thorough study of superficially treated 2024 aluminum alloy combined with steel drill pipe in crooked well trajectory is presented in this study. Basically; this study is built on several parameters that affect fatigue resistance of a drill pipe such as fatigue endurance limit of the drill pipe material, drill pipe specification, torque and drag loads applied, dog leg severity, besides crooked trajectory. Chiefly, this paper shows a full study about 2024 aluminum alloy drill pipe and analyzes the prospect of using aluminum drill string for deep wells while the fatigue, torque and drag as well as drilling efficiency and drill string integrity stay acceptable. It also gives a better comprehension of the mechanical behavior of lightweight material for drill pipe, which can significantly improve well planning in order to drill wells with an increasing depth, length and complexity. Additionally, even though steel drill pipe has better mechanical properties in terms of density, Young’s modulus, yield and tensile strength, than 2024 aluminum alloy drill pipe, the latter has a good fatigue resistance even in the simultaneous presence of high applied torque and axial load, and severe doglegs, which makes the use of other options (Steel Drill Pipe and Titanium Drill Pipe) impractical from the fatigue failure standpoint. Finally we can assume that, there is significant cost saving with the use of Aluminum Drill Pipe compared to steel drill pipes, because the ratio of the engine power needed to supply the drilling fluid at the required pressure for ADP versus steel drill pipe is lower, leading to a reduction in fuel consumption.