Multi-objective Optimization of the Drilling Process Considering Rate of Penetration Fluctuation

In order to improve drilling efficiency while ensuring production safety, a multi-objective optimization method for drilling process is proposed in this paper. This method takes maximizing rate of penetration (ROP) and minimizing ROP fluctuation as the optimization objectives, it uses weight on bit (WOB) as a decision variable. Firstly, taking into account the motion characteristics of drill string and the rock breaking mechanism of bit, an axial drill string model is established. Secondly, amplitude spectrograms and variational mode decomposition are employed to extract valid signals from actual drilling data. Thirdly, a multi-objective optimization model for drilling process is developed based on the axial drill string model and the valid signals. Non-dominated sorting genetic algorithm-II (NSGA-II) is employed to solve the multi-objective optimization model. Finally, in order to validate the effectiveness of the proposed method, this paper carries out simulations using actual drilling data from a well site in Xiangyang, Hubei Province.