Numerical Investigations on the Effect of a Cuttings Bed Remover on the Cuttings Carrying Capacity in Horizontal Drilling

Abstract

With the increasing development of the exploration of unconventional oil-gas resources, people pay more and more attention to horizontal drilling technology. During the process of horizontal drilling, when the deviation angle exceeds the critical value, the falling velocity of the cuttings in annulus will increase with the deviation angle and they are more inclined to slip to the bottom edge. If the drilling parameters are chosen improperly at the same time, the cuttings would be deposited to form a cuttings bed at the bottom edge of the annulus. The high friction and high torque caused by the cuttings bed could greatly reduce the efficiency and the safety of drilling. This paper comes up with a cuttings bed remover with helical grooves to break the cuttings bed and carry cuttings based on the normal drill pipe design, builds 3D models of the cuttings bed removers with different structure parameters to analyze the cuttings carrying capacity with CFD. In addition, an investigation about the effects of the grooves design and drill pipe rotational speed have on the cuttings carrying capacity is accomplished, the grooves design parameters include the number, the length and the helical angle of the groove, and the effects are evaluated by the flow characteristics of fluid field and transportation of cuttings. The remover structure is optimized according to the simulation results, and the good performance of cuttings bed remover is verified by a field test. The whole research about the promotion of cuttings bed remover and its application shall be of great importance to the improvement of horizontal drilling efficiency and safety.