Research on deviation correction characteristics of automatic vertical drilling tool

Abstract

The automatic vertical drilling tool can solve the problems of poor effect of conventional drilling. In order to effectively improve the ROP (rate of penetration) and quality of vertical wells, an automatic vertical drilling tool is developed in this article. This new innovative design has these performances, such as high temperature resistance, strong reliability. By analyzing the drilling trend with drill string system, the tool deflection correction ability was studied. Based on the longitudinal and horizontal bending continuous beam method, the BHA mechanical models of the automatic vertical drilling tool, including the calculation formulas of the lateral force and rotation angle, were established considering the variable cross-section treatments. The drilling trend prediction model was derived by formation interaction functions, and verified by numerical examples and experimental tests. On these bases, taking the trend angle of well inclination as the evaluation indicators, combined with the lateral force and rotation angle of drilling tool, the influencing factors of this tool deviation correction ability were analyzed. These calculation and experimental test results show that: the WOB, thrust force, bit anisotropy and formation anisotropy have a significant impact on the tool deflection correction ability. Furthermore, the research results can supply theoretical references for the vertical drilling and design of similar tools. Also, this research can provide basis for the optimization of drilling parameters, and the prediction and control of the wellbore trajectory.