Mechanistic Approach in Designing BHA's and Forecasting Wellbore Position

Abstract

Abstract BHA bending analysis and drilling ahead prediction are important topics because they can improve drilling efficiency and help prevent unplanned borehole deviation. Without them, there is extra risk of undesirable deviation which can cause severe drilling problems and greatly increase the cost of drilling. This paper presents the analytical basis and field applications of an integrated computer method in directional drilling. The method includes two-dimensional BHA bending analysis for designing BHAs and predicting their deviation tendencies, and a heuristic formation-bit interaction model for forecasting the future wellbore position while drilling. Using this computer method, parametric studies are performed on several single and multi-stabilizer bottom hole assemblies to demonstrate the effects of stabilizer placement and wear, WOB (weight on bit), hole angle, and borehole current curvature on the deviation tendency of these assemblies. Predicted wellbore positions from the drilling ahead model are compared with actual field data for two directional wells.