Research on the factors influencing the skew-making ability of structural bent-angle drilling tools and structural optimization

Abstract

The structural bent-angle drilling tool is a new type of directional drilling tool developed independently, in order to improve its build-up rate and better play its trajectory capacity, in order to successfully achieve directional drilling. To this end, this paper establishes a mechanical model of structural bent-angle drilling tools by using the longitudinal and transverse bending method of BHA continuous beams, conducts a study on the influencing factors of their skewing ability, and grasps the influence law of drilling tool structure on their skewing ability. In addition, in order to study the build-up rate of structural bent-angle drilling tools under the action of multiple factors, the drilling tool structure is optimized based on orthogonal tests. The results show that the lateral force of the bit decreases with the increase of the curvature of the well body and the decrease of the structure bending angle, the bit pressure and the diameter of the near bit holder. The build-up rate increases with the increase of the structure bending angle, the bit pressure, the diameter of the near bit holder and the distance from the bit to the near bit holder. The structure bending angle is the main factor affecting the build-up rate of the structure bending angle drilling tool, and the build-up rate of the optimized structure (structural bend angle(γ)=0.9°, bit pressure(PB)=6t, near drill bit holder diameter(D1)=0.215m, distance from drill bit to near drill bit holder(L1)=0.6m) is 8.3939°/30m, which is 65.5% higher than the original structure (γ=0.5°; PB=3t; D1=0.212m; L1=0.6137m)(2.8949°/30m). The research results can lay the theoretical foundation for improving the build-up rate of structural bent angle drilling tools.