Rock-breaking analysis model of new drill bit with tornado-like bottomhole model

摘要

For improving the rock-breaking efficiency of oil and gas drill bits, a new drill bit is presented with tornado-like bottomhole model (named swirling cutting bit). The new drill bit cutter breaks rock with shocking and cutting effect during the drilling process, and the elements on largest ring cross the borehole center with high speed. It can effectively improve the center rock-breaking efficiency. Meanwhile, for all cutters on different rings breaking rock at the same time, it can optimize the rock-breaking volume of each element and improve the bit service life. To analyze the interaction features between cutters and rock, the position equations are established by the cylindrical coordinates and complex movement principles, and then the velocity and acceleration equations can be obtained. Based on the numerical example results, this paper analyzes the bottomhole model, the contact section, and the distribution features of velocities and accelerations on different rings. By analyzing the acceleration results, we can study the failure mechanism of cutters. At the same time, lab experiments test the bottomhole model and rock-breaking features, and it verifies the accuracy of calculation method and equations. Moreover, the analysis method and models are also applicable to other types of bits or composite bits, and the inputting parameters need corresponding adjustment for different type of bits.