Critical Buckling Load Assessment Of Drill Strings In Different Wellbores Using The Explicit Finite Element Method

Abstract

Abstract Previous theoretical formulations for sinusoidal and helical buckling of drill strings vary significantly and are mostly proposed for frictionless pipes without tool joints. Finite element analysis (FEA) methods have the ability to consider geometric details and large deflections. However, traditional FEA methods use shell or solid dimensional elements for this problem and are computationally expensive. In this paper, an explicit FEA based on beam and connector elements implemented in the Abaqus software is employed to study the buckling of drill strings in different wellbores. The wellbore geometry, stiffness, friction load, and friction induced torque are modeled using connector elements. A typical drill string in vertical, inclined, horizontal, and curved wellbores is simulated and the explicit FEA results for sinusoidal and helical buckling loads are compared to different theoretical formulations and experimental results in the literature. The effects of length, inclination angle and string effective weight due to buoyancy as well as the effect of tool joints in straight and curved wellbores is also studied and compared to present formulations and published experimental results. Overall, it is demonstrated that using explicit FEA can efficiently study drill strings buckling behavior in straight and curved wellbore conditions.