Abstract:
Drilling operations in fractured formations in the Sichuan–Chongqing region are frequently accompanied by severe lost circulation, resulting in prolonged non-productive time and increased drilling costs. Efficient control of lost circulation has therefore become one of the major challenges restricting drilling efficiency in these formations.To address this issue, a vector push-type PDC drill bit was developed based on the design concept of increased blade number, weakened gauge protection, and enlarged hydraulic nozzles. The proposed bit utilizes the scraping, pressing, and vector push actions generated by the plugging blade during drilling to continuously force the plugging material into leakage channels, thereby improving plugging efficiency. Taking each blade as the basic load-bearing unit, the lateral cutting forces acting on individual blades were vectorially optimized so that the resultant lateral force was directed toward the plugging blade. Meanwhile, the inclination angle between the plugging blade and the borehole wall was optimized to enhance the directional extrusion and embedding capability of the plugging material. Based on this design concept, a complete personalized design methodology was established, including cutter layout optimization, cutting mechanics analysis, and numerical simulation of the flow field.The simulation results demonstrate that the proposed drill bit maintains favorable drilling performance while providing stable lateral supporting force and excellent operational stability. Laboratory drilling tests and field applications further verified its engineering feasibility and plugging performance. Field results indicate that the vector push-type PDC drill bit effectively enhances the squeeze-plugging capability, reduces lost-circulation treatment time, saves more than two drilling trips per well, shortens the overall complex-operation cycle, and significantly lowers drilling costs.