Optimal Design of the Flow Field of Bi-center Bit

Bottom-hole flow field is determined by the hydraulic structure of PDC bit, it is one of the important factors that affect the performance of the bit. The flow field optimizing is an important means of improving the hydraulic performance of drill bit. Because of the complicated structure, the performance of bi-center bit is different from conventional bit, thus its flow field is necessary to be optimized. In this paper, an evaluation method of the bottom-hole flow field of the bi-center bit is proposed, the relationships between flow distribution, nozzle angle and cuttings carrying effect are studied with numerical simulation method, the reflux distributions of the bottom-hole flow field are obtained under the different combinations of different size nozzles and nozzle spray angles, the hydraulic structure of the bit is optimized according to the numerical simulation results, then an optimal hydraulic structure of bi-center bit is obtained