The Research And Application Of PDC Bit In Compound Drilling

Composite drilling mode can not only have continuous control of well track and reduce the times of tirpping, but also increase the rate of penetrate , which is a kind of high-efficiency controllable drilling way earning widespread respect and being used widely in practical application. The conventional PDC bits have been designed according to the turntable well driving, so it needs higher torque.Under the conditions of certain bit pressure, the mud motors could happen the phenomenons of despinning and braking easily, so that they can't reach the expected effect of the composite drilling. Combined with the formation drillability evaluation of Qingyang block and the special needs of composite drilling skills, it is significant to develop the new type of composite PDC bit for improving the drilling rate of the whole Qingyang block.Downhole flow field is the place that the hydraulics issue of bits can be directly displayed. According to the analysis of flowing phenomenon in the downhole flow field, we can find the problem of bit hydraulics, match the jets reasonably and design the chip area.Because of pdc downhole flow field is the complicated 3d non-free strands of jet turbulent flow field,it's difficult to get the flow characteristics of the jet with the theoretical and experimental methods. Through developing technology research of PDC bit downhole flow field simulation analysis , this project established a mathematical model for optimal design of hydraulic parameters of PDC bit , developed a optimization design software about PDC bit hydraulic parameters , and provided the reliable theory basis and method for hydraulic structure optimization design of the PDC bit . The result has important engineering practical significance in guiding the hydraulic structure optimization design and improving the performance of the PDC bit .