To Improve Drilling Efficiency by Multi-objective Optimization of Operational Drilling Parameters in the Complex Geological Drilling Process

Operational drilling parameters optimization is necessary for increase drilling efficiency in complex geological drilling process. There are four key objectives to evaluate the drilling efficiency, including drilling cost, rate of penetration (ROP), drill bit life, and drill bit's specific energy. In this paper, we proposed a multi-objective optimization method to improve drilling efficiency in the complex geological drilling process considering all the four key objectives. Firstly, the characteristics of complex geological drilling process and optimization problems are analyzed to find the vital process parameters and problems for drilling efficiency optimization. Then, a multi-objective optimization model which combines the four key objectives is established. Finally, an improved nondominated sorting genetic algorithm (improved NSGA-II) is used to optimize the operational drilling parameters include weight on bit (WOB) and rotational speed (RS) to make drilling efficiency improved. The real case results demonstrate that our method increases the drilling efficiency in four key objectives and saves the simulation time. The proposed method provides the foundation for intelligent optimization control in complex geological drilling process.