Research And Design Of Composite Cylinder Heave Compensation System For Drilling

Semi-submersible platform, drilling ship and other floating drilling devices are mostly used to drill in the deep-sea oil development. The heave motion of drilling platforms is caused by the wave. The heave motion leads to the motion of dtill string, which results in the instability of drilling pressure and reduce the service life of drill bits, or even have to stop drilling. This increases the drilling costs. Therefore, a drill string heave compensation system is needed to compensate the heave motion.To study the relationship between the displacement of the hook and the variable quantity of drilling pressure, this paper built the dynamic model of the drill string, used the series method to solve the vibration differential equation of the drill string and obtained the relationship between the displacement of the hook and the variable quantity of drilling pressure. The maximum of the hook displacement allowed is 83.8mm in the drill string length of 10000m, which is approximately figured out by the Matlab program.Based on the research of the existing heave compensation systems, the composite cylinder heave compensation system for drilling is proposed. The main structure and hydraulic system parameters are designed and calculated, then the mathematical model is set up. On this basis, the system simulation model is simulated with Simulink. Simulation results show that the working vessel volume may be determined as 12m3, the performance of compensation system is better and meet the requirements of various drilling processes,and energy consumption is lower.The required working vessel volume is obtained by the simulation, when the compensation system is under the different sea condition. The volume value can be used as the reference value of the actual operation.To verify the simulation model and research the composite cylinder-type heave compensation system, the composite cylinder-type heave compensation system simulation experiments is designed, and several sets of hydraulic control program is put forword. The effects and energy consumption of various programs are compared through simulation experiments in order to find out the best hydraulic control scheme of composite cylinder-type heave compensation system.