The New Method and Application of Friction Torque for Extended Reach Well

Abstract

The extended reach well has the characteristics of long horizontal displacement, big hold angle and long open hole. The forecast and control of friction torque is one of the key factors of successful drilling of extended reach well. Based on the characteristics of extended reach well, considering the effect of drill string stiffness and drill string buckling on the friction & torque of the tube, a modified 3D soft-string calculation model for friction & torque of the extended reach well is proposed. The corresponding software has been programmed, and the model is applied in well A. The calculation result shows that the new method’s calculation result is consistent with the experimental result, and the torque and hook load errors are within 10%. The method could satisfy the engineering requirement, which provide a good guidance for the friction & torque analysis in the process of profile optimal design and drilling operation for the extended reach well. Key words : Extended reach well; Friction＆torque; Drill string stiffness; Drill string buckling; Drilling operation