Research And Design Of Crown-block Heave Compensation Test-bed

When well drilling is operating in deep sea,the drilling ship or semi-submersible platform would have 6 degrees of freedom movements:surging,swaying,heave,pitch,roll and heading motion.The drill string would generate periodical shuttle movement driven by the heave motion of the drilling platform,which causes the variation of the drilling pressure,decreases the drilling efficiency and reduces the service life of the bit.The bit can even detach from the well bottom and cause accidents in harsh sea conditions.Therefore heave compensation device need to equipped on drilling platform to offset the heave motion of the drilling platform,ensure the vertical position stable and keep the drilling operation working smoothly.The load,compensation etc.of the test-bed are determined using similarity theory and based on the structure parameters and working parameters of the heave compensation device.Then a scheme is designed to enable the verification of the compensation effect in laboratory and the hydraulic system is designed.The force analysis model is built in Simulink based on the design parameters of the test-bed and the force of heave compensation cylinder on crown block is obtained.Then the working area of the passive compensation chamber of the heave compensation cylinder is established.The calculating model of accumulator volume and compensation power is built in Simulink based on the force of the heave compensation cylinder and the working are of the cylinder.And the calculation result shows that when the accumulator volume is 200 liter,the energy consumption of the compensation system and the space occupation are relatively small.According to the force of the heave compensation cylinder and the system working pressure,the structural parameters of the compensation cylinder such as diameters of the inside and outside cylinders,wall thickness,hydraulic fluid size,length of the cylinder are established referring to design methods of cylinders in mechanical design handbook.The sea elements,load simulated cylinder and heave simulated cylinder are selected based on their own force and working principle.Then the three-dimensional model of each elements and the test-bed is built in SolidWorks.Importing the three-dimensional model of the test-bed into ADAMS,the mechanical simulation model is built,the hydraulic system model is built in AMESim and the co-simulation model is completed.After running the co-simulation model,the compensation effect and energy consumption is obtained.The simulation result shows that the passive compensation effect is not ideal,the active and semi-active compensation effect is very good,the energy consumption of the semi-active compensation is significantly small compared with the active compensation and the energy consumption of the semi-active compensation reducing with the increasing of the accumulator volume.