Application of Cellular Automata Modeling to Simulate Bottom Hole Assembly Performance

Bottom hole assembly (BHA) component failures continue to afflict the oil and gas industry, annually involving huge amount of direct and consequential cost. However, actual assemblies and drilling situations are too complex to rely on the simpler idealizations that do not account for varying collar dimensions, material properties, and multistabilizer arrangements. Recognizing this, cellular automata (CA), an idealizations of complex systems which is especially advantageous for modeling complex dynamic problems, is used to simulate BHA performance in this paper. At first, a drill string dynamic model is established, and the collision conditions between the drilling string and well wall are obtained. Then a new numerical solution method based on CA is proposed to solve the model. In the end, a practical example with a widely used tower type BHA is given, successfully solved, and the computational results are presented. The solutions for this assembly show various reaction forces, displacements and the position of tangent points. From the side force at the bit, the general inclination tendency can be determined, and the stability of the BHA can also be evaluated by the position of tangent points and their forces. This new method has advantages of programming simply, applying boundary condition easily, small calculation storage space and rapid convergence rate etc.