Field Comparison of 2-D and 3-D Methods for the Borehole Friction Evaluation in Directional Wells

Abstract

ABSTRACT The two new general procedures for the borehole drag prediction, based on the borehole friction factor concept were compared. The procedures employed iteration over the directional survey stations, numerical integration between the stations and mathematical models of the axial loads within a moving pipe in the borehole. The models considered several new effects such as hydrodynamic viscous drag, contact surface, and the bearing angle component of dogleg severity. The study addressed the extent and conditions under which the two-dimensional and the three-dimensional procedures diverged significantly. The method was based on the computer calculated values of the borehole friction factor from the measured hook loads. The field data used included four casing runs from the offshore locations in the Gulf Coast area. In addition, the systematic theoretical study was performed with over 100 computer-simulated directional wells. The study revealed a good agrement between 2-D and 3-D procedures for most common drilling conditions. Two 2-D model's accuracy was mostly affected by the bearing angle component of shallow doglegs. In addition, the reliability of the borehole friction factor field assessment was mainly controlled by the inclination angle and the length of the slant hole section of a well.