An ROP Improvement Technology Based on Adaptive Matching Between the Rock-Breaking Energy of Bits and Rock Features

In view of the demand for the rate of penetration (ROP) improvement in deep, ultra-deep, and complex formations, a ROP improvement technology based on adaptive matching between rock-breaking energy of bits and the rock features was proposed considering the change in the drillability of deep rock. Based on the analysis of torque characteristics of bit during rock breaking, an adaptive matching tool was developed. The energy could be stored and released by the planetary gear and torsion spring in the tool, and could be stored in advance during drilling in lithologically homogeneous formations. In addition, energy could be released during drilling in gravel layers or heterogeneous formations to help rock breaking. The statics and dynamics performance tests verified the structural reliability of the tool and the feasibility of realizing the ROP improvement mechanism. Field test results in a deep shale gas well show that the ROP by the proposed technology is increased by 83% compared with that by conventional methods used in adjacent wells. The effectiveness of the tool in improving ROP and stabilizing bit performance is verified. As a result, the successful development of the tool and ROP improvement technology based on adaptive matching between rock-breaking energy of bits and rock features provides effective theoretical support and alternative technical approaches for improving ROP in deep, ultra-deep, and complex formations.