Optimization design of dynamic control parameters for multi-gradient drilling

Key words:  drilling  dynamic parameter optimization  particle swarm optimization algorithm  cyclone separator  narrow safe density window

Abstract:

In order to determine the important control parameters in multi-gradient drilling and optimize drilling efficiency, a dynamic parameter optimization model was established. In the improved model, the maximum drilling depth after the adjustment of the control parameters for a single drill bit trip and the maximum drilling depth under the same well structure were set as the optimized subjects. The position of cyclone and drilling fluid density were set as the optimizing parameters, and the constraint relationship between the drilling fluid cyclic equivalent density and safe density window as well as the drill bit life expectancy were the constraints. The optimization model was solved by a particle swarm optimization algorithm. The results of case study show that there are optimal position of the cyclone separator and density of the drilling fluid after each adjustment to make the drilling depth of each single trip longest. With the increase of the number of the adjustments, the optimal position of the cyclone separator from the drill bit and the optimal density of the drilling fluid are gradually increased, but the maximum drilling depth of the single trip is gradually reduced. The design of cyclone separator and bit life expectancy should be coordinated to avoid waste of rising and drilling.