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.

The wellbore friction, torque and drag, between drill string and the wellbore wall is the most important issue which limits the drilling industry to go beyond a certain measured depth.The calculation and analysis of torque and drag were considered to be very important in drilling and well design. A variety of models (soft, stiffness, mixed and finite element) have been used to determine the torque and drag. A FEA (Finite Element Analysis) model of the drill string to simulate it’s working behavior, involving contacts between the drillstring and borehole wall was developed, this FE Model was to be compared with computational model of torque and drag, and to be verified with experimental results.The drillstring displacements calculated by the FEA model matches those from commercial software in petroleum industry (Landmark). The model developed and discussed in this paper can be used for predicting torque and drag inside wellbores of oil and gas wells, and it will also benefit in preplanning simulation of oil and gas well drilling operations.

The Bottom Hole Assembly (BHA) design is consider a very important subject in the planning of any oil and gas well, and any mistake in BHA design will lead to additional increase in drilling cost, due to corrections needed in well trajectory.This study was intended to predict the trajectory path, by analyzing the tendency of the BHA to build, hold, or drop the angle of inclination. The other task of this work was to measure the effect of formation strength on wellbore trajectory. In this work finite element model (FEM) results are evaluated and verified using lab data supported with results obtained from some published analytical and numerical solutions and also verified with worldwide utilized software in Oil Industry (Landmark). The FE results significantly match with tubular mechanic lab data. The BHA model permits prediction of wellbore curvature based on both BHA mechanical behavior and geological influences.

The wellbore friction, torque and drag, between drill string and the wellbore wall is the most important issue which limits the drilling industry to go beyond a certain measured depth. The calculation and analysis of torque and drag were considered to be very important in drilling and well design. A variety of models (soft, stiffness, mixed and finite element) have been used to determine the torque and drag. a FEA (Finite Element Analysis) model of the drill string to simulate it’s working behavior, involving contacts between the drillstring and borehole wall was developed, this FE Model was to be compared with computational model of torque and drag, and to be verified with experimental results. The drillstring displacements calculated by the FEA model matches those from commercial software in petroleum industry (Landmark). The model developed and discussed in this paper can be used for predicting torque and drag inside wellbores of oil and gas wells, and it will also benefit in preplanning simulation of oil and gas well drilling operations.