Study on energy-saving mechanism and decoupling control scheme of compensation drawworks for deepwater drilling

Key words:  deepwater drilling  drawworks  heave compensation  bit feed  energy recovery

Abstract:

In order to solve the technical problems of electrodynamic compensation drawworks for deepwater drilling including high energy consumption, serious wear of wire rope and motion coupling, a new type of hydraulic power system based on energy recovery is putforward according to the analysis on energy-saving potential of electrodynamic compensation drawworks under different processes of offshore drilling operations. The hydraulic power system can recover and reuse the gravitational potential energy and inertial kinetic energy of system in the process of different drilling operations. The software and hardwaredecoupling control schemes which can realize the decoupling control of heave compensation movement and automatic bit feed movement are putforward according to the analysis on motion coupling mechanism of electrodynamic compensation drawworks. Then, the key structural parameters of the drawworks compensation system are calculated, and the principle prototype of compensation drawworks and the test system are developed. Simulation and experimental studies on the compensation drawworks are carried out under different sea conditions and working states. The results show that the new type of hydraulic power system has significant energy saving effect compared with the electrodynamic compensation drawworks. The service life of wire rope is increased by using the drawworks drum with large diameter. Moreover, the control effect of hardware decoupling schemes based on the differential planetary transmission and dual drawworks is good, which can meet the performance requirements of the offshore floating drilling.