Dynamic Analyses of Directional Drilling Using Curved Beam Theorem

Directional drilling technique can provide flexibility in rig location selection as well as increase drilling and production efficiencies through extended reach to isolated reservoirs. However, as well complexity increases, analyzing the mechanical performance of the associated drillstring and its components becomes more difficult. A standard Finite element method (FEM) can accurately analyze directional drilling statics and dynamics by discretizing the structure into a series of straight beam elements. However, this method has a drawback of high computational cost. To increase the computational efficiency, this paper introduces the application of curved beam FEM to model directional drillstring. The minimum curvature method is applied to obtain directional well profiles in which the adjacent survey points are connected by circular arcs. Based upon this assumption, the curved beam is used to model the curved drillstring to minimize the discretization error and to increase the computational efficiency. Static and dynamic analyses are carried out to verify the proposed method. As compared to the straight beam approximation method, fewer elements are needed to obtain a given accuracy, leading to more efficient simulations. The utility of the proposed model is also demonstrated through analyzing realistic drilling scenarios.