A method for predicting the build-up rate of single-bending positive displacement motor assembly in compound drilling

Abstract

Accurately predicting the build-up rate of single-bending positive displacement motor (PDM) assembly in compound drilling is helpful to rational design the well trajectory, realize compound drilling in long well sections and improve the rate of penetration. Based on the calculation model of corrected build-up rate of single-bending PDM assembly in sliding drilling, the build-up rate calculation method of single-bending PDM assembly in compound drilling was established by combining the trajectory measurement data of the drilled sections, and the influence law of parameters such as bending angle, weight on bit, bit anisotropy index and formation inclination on the build-up rate of compound drilling was analyzed. And the following results are obtained. First, the build-up effect of the single-bending PDM assembly during compound drilling is mainly the result of the leverage effect and pendulum effect of the drill tool assembly, as well as the natural deviation of formation. Second, the composite drilling build-up rate is related to the drilling tool structure, bit performance, drilling parameters, formation inclination and other factors. In conclusion, the factors affecting the build-up rate of conventional drilling tool assembly also have impacts on the composite drilling build-up rate of single-bending PDM assembly. The method is important for the control of well trajectory during compound drilling.