Control of Down-Hole Drilling Process Using a Computationally Efficient Dynamic Programming Method

The unconventional down-hole resources such as shale oil and gas have gradually become a critical form of energy supply thanks to the recent petroleum technology advancement. Its economically viable and reliable production highly depends on the proper operation and control of the down-hole drilling system. The trend of deeper drilling in a complex environment requires a more effective and reliable control optimization scheme, either for predrilling planning or for online optimal control. Given the nonlinear nature of the drilling system, such an optimal control is not trivial. In this paper, we present a method based on dynamic programming (DP) that can lead to a computationally efficient drilling control optimization. A drilling dynamics model that can enable this method is first constructed, and the DP algorithm is customized so that much improved computational efficiency can be achieved compared with using standard DP. A higher-order dynamics model is then used to validate the effectiveness of the optimized control, and the control robustness is also evaluated by adding perturbations to the model. The results verify that the proposed approach is effective and efficient to solve the down-hole drilling control optimization problem.