Research On Multi-objective Optimization Technology For Complex Well Trajectory

One of Petroleum drilling engineering's key technologies is the well trajectory parameters optimization.In order to achieve optimal technical and economic indicators for the drilling process,it refers to use the scientific optimization methods through while drilling logging data and well logging data,analyze various factors affecting the direction of the well trajectory,and select the most appropriate well trajectory parameters.In the actual drilling engineering,this paper takes double-inclined seven-segment complex well trajectory under the premise of ensuring the safe operation of the drilling and the wellbore,analyzes and compares the existing objective functions such as optimal trajectory length,optimal horizontal well trace,minimum friction torque and maximum drainage area,builds the single-objective optimization model and multi-objective optimization model respectively with the constraints of drilling tools,target targets,depth of kick off point and total design vertical depth.The main research results and contents of the model as follows:(1)Taking the shortest true measuring depth as the optimized objective function and using the constrained single-objective particle swarm optimization algorithm,which obtain the global optimal result of TMD is 1.48*10~4 ft.The comparison optimization results prove that the introduction of the new algorithm speeds up the optimization and meets the real-time requirements of optimization.(2)With the minimum true control torque as the optimized objective function,which obtain the global optimal result of true control torque is 1.18*10~4 N*ft.The improved particle swarm optimization algorithm is used to optimize the parameters such as wellbore,inclination,well azimuth and well segment curvature,and the result of optimizing the true control torque is better.The algorithm runs fast and takes a short time.(3)According to the actual drilling tool combination and complex well design constraints,propose an improved multi-objective particle swarm optimization algorithm with the well trajectory optimization objective functions of min{true measuring depth,true control torque},which realize the optimal combination of the wellbore trajectory parameters such as wellbore,inclination,azimuth and wellbore curvature,guide the actual drilling process.Through the research on the single-objective,multi-objective optimization model and optimization method of the wellbore trajectory,this paper lay the foundation of the multi-objective dynamic optimization of the interactive while drilling wellbore trajectory and realize the precise control of the wellbore trajectory,rectification,anti-collision and improvement of the target rate.