Method for Designing the Optimal Trajectory for Drilling a Horizontal Well, Based on Particle Swarm Optimization (PSO) and Analytic Hierarchy Process (AHP)

In horizontal well drilling, the success of the drilling operation mainly depends on optimal selection of the drilling trajectory. In this paper-, we propose a method for optimizing horizontal well trajectory design based on the numerical optimization methods PSO (particle swarm optimization) and AHP (analytic hierarchy process). We selected four functions as the parameters which affect the selection of the optimal solution: the shortest length of the well trajectory, the highest target hitting accuracy, the lowest cost of drilling, and the least drilling string friction. The key parameters for a horizontal well (the KOP (kick-off point), BUR (buildup rate), and hold angle) were calculated by ththe PSO method in Matlab. Applying the AHP mathematical tool for a systematic approach to decision-making, we ranked the solutions according to the engineering and design requirements. The new method proposed in this paper lets us overcome the limitations of the optimization algorithm and to recast empirical judgments of experienced analyzers in mathematical language, thus avoiding subjectivity in selecting the best solution. The method was applied to and tested on conditions of the Yanchang field. As shown by the experimental study, the proposed method is a simple and reliable method for selecting the optimal trajectory.