Deviation Performance Analysis Of Directional Rotary Steering Drilling System

Rotary-steerable drilling technology is a sign of automation and intelligence in modem drilling engineering and represents the leading level of today's oil drilling engineering.The point-the-bit rotary-steerable drilling tool itself has many advantages,making it the development direction of future rotary-steerable drilling tool.Nowadays,foreign point-the-bit rotary-steerable drilling tools are maturing and are gradually expanding their scope of application.Although domestic companies have done a lot of research,there is still no point-to-point rotary-steerable drilling tool that has been put into commercial applications in the true sense.At present,the conventional point-the-bit rotary-steerable drilling system has the problems of poor deflecting performance and high operating cost,make it difficult to completely replace the traditional motor directional drilling tool.The emergence of high build-up rate point-the-bit rotary-steerable drilling tool has effectively solved this problem.However,research in this field in our country has only just begun.We have not yet mastered core technologies and urgently need to strengthen research.The analysis of deflecting performance of point-the-bit rotary-steerable drilling tools is an important research content in the design process of such tools.This paper elaborates on a set of methods for analyzing the deflecting performance of point-the-bit rotary-steerable drilling tools which bending moment is discontinuous.Firstly,a set of typical normal build-up rate and high build-up rate point-the-bit rotary-steerable drilling tools from abroad which bending moment is discontinuous are selected,abstracted and simplified in terms of their structure,and the special boundary conditions of the tool and beam theory of the vertical and horizontal bending method are used to establish the analysis.Through programming and calculation,the bit lateral force and ultimate curvature of the tool under different working conditions can be obtained.Then,the deflecting ability of the two point-the-bit rotary-steerable drilling tools was compared,and the main factors that caused the different deflecting ability were analyzed.At the same time,the effects of drilling pressure,well inclination,well curvature,tool eccentricity and tool body bending angle on the deflecting performance of point-the-bit rotary-steerable drilling tools are summarized.Through the investigation of point-the-bit rotary-steerable drilling tools at home and abroad,and based on the influencing factors and laws of the deflecting performance of point-the-bit rotary-steerable drilling tools obtained through analysis of the model established,this paper proposes a design scheme for a high build-up rate point-the-bit rotary-steerable drilling tool and studies its guiding mechanism.The proposed method,which is used to analyze the deflecting performance of the point-the-bit rotary-steerable drilling tools,is applied to analyze the designed tool.The results show that the design scheme can achieve the level of build-up rate of foreign similar products,and it provides a way of thinking on high build-rate point-the-bit rotary-steerable drilling tool's research and development.Based on the analysis method of the deflecting performance of the point-the-bit rotary-steerable drilling tool which bending moment is discontinuous elaborated in this paper,a set of software was developed,and the practicality of the software is verified by an example.The software can accurately analyze the deflecting performance of several sets of point-the-bit rotary-steerable drilling tools at home and abroad,and provide a computing platform for the design of the point-the-bit rotary-steerable drilling tools.