Prediction of Performance of Rotary Bottom Hole Assembly For Directional Well

Abstract

A finite element model was constructed to predict inclination tendency for multistabilizer rotary BHA in three dimensions, static condition. The bottom hole assembly was idealized with beam element capable of resisting axial forces, bending moments about the two principal axes, and twisting moments about its centroidal axis. Bit and stabilizer were treated as contact point and restricted from movement in all directions. Each element is loaded with gravity and normal contact forces.

          Model validation showed closer agreement between the model and Jiazhi's method (analytic) for slick, single, and two stabilizers BHA, compared to Akgun results. Predictions with finite element model showed that for building assembly, the weight on bit had small effect on bit side force especially in high angle wells. Also inclination tendency (building, dropping) would depend on position of the stabilizer, diameter of drillcollar behind the bit, and number of stabilizers.