Finite Element Method for Simulating the Effects of Torque and Drag On Buckling of Tubular inside Borehole of an Oil and Gas Wells

摘要

Tubular buckled inside wellbore section of oil or gas wells may cause problems such as: Casing wear/failure, Eliminates the transmission of axial load to the Bit, Drillpipe fatigue, Bit direction change, Severe drag and torque, Tubing seal failure, Connection failure. According to what mentioned above, it would be necessary to make an investigation on the effect of drag and/or torque on buckling of tubular inside horizontal wellbore (the so-called torque-drag-buckling relationship), the study depends mainly on conducting experimental tests and develop Finite Element Model, and utilize the results to predict the tubular behavior under different circumstances of torque and drag, also these results were compared and verified with some of theoretical approaches. Results obtained from this study indicates that torsion load had a little effect on buckling of tubular in horizontal section, this effect increase with decrease in pipe stiffness. Helical buckling tends to increase highly drag force, and thus eliminates transmission of axial load to the bit. Drag force tend to increase with torsion load as a result drag increase helical buckling. For prediction of helical buckling Lubinski and Woods, Gao Deli and Chen et. al provided a good agreement with one-end hinge condition, and Dellinger equation is the best for two-end hinge boundary condition.