Analysis On Mechanical Properties Of Positive Displacement Motor Assembly And Its Applicationin Coal Mine Engineering Hole

During directional drilling in the coal mine engineering hole ,the lateral force on bit is one of major mechanical properties of the positive displacement motor assembly (PDM), which includes the bent sub-positive displacement motor assembly (BS-PDM) and the bent housing-positive displacement motor assembly (BH-PDM). On the basis of the basic mechanics equation ,the forced condition of the PDM is analysed,and mechanics and mathematical models are set up for two dimension and three dimension static analysis of the two types under small deflection,and their weighted residual solutions are given.In this paper,the author used MATLAB to design calculation programme. The quantitative analysis of the major parameters influencing on the lateral force on the bit are made. These parameters includes bit pressure, hole curvature, inclination angle, bending sub angle, tool face setting angle, the distance between bit and curved joint, equivalent stiffness of PDM and stiffness of dirlling tool upside of curved joint ,etc. Comparing BS-PDM with BH-PDM, this paper analysed the ability of creating inclination of the two type. Combining with the engineering of the coal mine hole, this paper applied the conclusions to guide the direction drilling and achieved favorable effect,and the practical measured datum testified the validity of theoretics analysis. The major conclusions of the analyses on mechanical properties of PDM assembly in this paper are valuble and guidable to the design and construction of directional drilling in the coal mine engineering hole.