Critical-Buckling-Load Assessment of Drillstrings in Different Wellbores by Use of the Explicit Finite-Element Method

Abstract

Previous theoretical formulations for sinusoidal and helical buckling of drillstrings 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 nonlinearities. However, traditional FEA methods use shell or solid elements for this problem and are computationally expensive. In this paper, an explicit FEA that is based on beam and connector elements implemented in the Abaqus software (2012) is used to study the problem in different wellbores. The wellbore geometry, formation stiffness, friction load, and friction-induced torque are modeled with connector elements. A typical drillstring in vertical, inclined, horizontal, and curved wellbores is simulated, and the explicit FEA results for sinusoidal-and helical-buckling loads are compared with different theoretical formulations and experimental results in the literature. The effects of length, inclination angle, and string effective weight caused by buoyancy as well as the effect of tool joints in straight and curved wellbores are also studied and compared with present formulations and published experimental results. A full-scale well-buckling test has also been simulated, and load-transfer data are compared with the real-world results. Overall, it is demonstrated that the use of explicit FEA can efficiently study drillstring buckling behavior in straight-and curved-wellbore conditions. Purpose and ScopeThe purpose of this paper is to demonstrate the efficacy of the use of the explicit FEA method to model the buckling behavior of

A review of down-hole tubular string buckling in well engineering

“…When the length between two adjacent connectors reaches the critical value where the tubular string is just in point contact with the wellbore, the critical buckling load achieves its minimum value. Gao's results were proved to be in good agreement with numerical calculation (Daily et al 2013;Hajianmaleki and Daily 2014).…”

Experimental Investigation and Analysis of Dynamic Buckling of Drill String in Horizontal Well

“…Buckling can intensify the bending stress and lead to fatigue over time. More importantly, buckled shapes exert larger side forces than unbuckled which increases friction losses and can lead to the lockup of the string and the potential loss of equipment and section of the well [1][2][3]. The buckling includes the static buckling and the dynamic buckling.…”

Numerical simulation of the drill string buckling behavior in horizontal wells considering the orthotropic friction

“…Firstly, the gravity is applied in 10seconds. Secondly, a small transverse force P=0.02×mg sin(0.5πt) is loaded in the middle of the drill string in another 10 seconds, acting as a trigger for the onset of the buckling [8]. Finally, the drill string is compressed along the x-direction with a steady speed of 0.2 mm/s until the fully helical buckling occurs.…”

“…For comparison, the force-displacement curve of the top end is selected to characterize the critical buckling forces [8]. As seen in Fig.…”

“…Later, Gao and Miska [6,7] considered the effect of the tangential friction, and induced the formulations for the sinusoidal and helical buckling force. Recently, Hajianmaleki and Daily [8] studied the critical buckling and the axial force transfer issue using the finite element model established in Abaqus. Miller et al [9], based on the finite element method, researched the buckling behavior of the Kirchhoff rod constrained in a horizontal pipe under the influence of the isotropic friction.…”