Force Analysis And Build-up Rate Prediction Of Single Bend PDM Drill Assembly

With the booming development of the economy and society,the demand for oil and gas resources is increasing in the world,and the consumption of these is increasing year by year.In order to meet the needs of economic and social development,countries all over the world have increased their efforts to exploit oil and gas resources,as a result,there are fewer and fewer oil and gas resources are easy to be exploited,horizontal well,directional well,multilateral well and extended reach well have developed rapidly.In the process of drilling,it is necessary to control the well trajectory accurately.At present,the main technology of well trajectory control in our country is conventional steering drilling tools,and the single bend PDM drill tool is one of the most widely used deflecting tool.Therefore,the key to control the well trajectory is to analyze the stress and accurately predict the build-up rate of single bend PDM drill assembly.First of all,this paper introduced the purpose and significance of the research,the present situation of statics analysis about the BHA and the development of the build-up rate prediction are also briefly analyzed.In view of the initial bending and structural angle of the BHA,according to the criterion of equal deformation energy,the initial bending is equivalent to uniform load,and the concentrated force is used to equivalent the structure angle according to the equal bending moment.Considering the problem of variable stiffness in drilling,the single bend PDM drill assembly is simplified as the beam subjected to axial and transverse bending load,and the mechanical model of single bend PDM drill assembly is established.According to the mechanical model,the three-moment equation of the single bend PDM drill assembly is established with the boundary condition and the continuous condition,and the formula of the side force is obtained.Taking the single bend PDM drill assembly with single stabilizer and double stabilizers as an example,the effects of the structure parameters,drilling pressure and well trajectory on the side force of the bit and limit build-up rate of the single bend PDM drill assembly are studied,and verified by actual drilling data.In addition,the software of force analysis and build-up rate prediction of single bend PDM drill assembly is developed by using the mixed programming technology of C # and Matlab.The single factor analysis and sensitivity analysis of single bend PDM drill assembly are carried out,and the calculation efficiency of build-up rate prediction is improved.Based on the study of force analysis and build-up rate prediction of the single bend PDM drill assembly,the limit build-up rate is obtained,and the influence of various factors on the build-up trend is pointed out.The research in this paper can guide the drilling operation,and have certain guiding significance for the structure optimization of single bend PDM drill assembly and optimization of drilling parameters in the drilling.