Study On Constant Drilling Pressure Control System Of Semi Submersible Drilling Platform

Oil resources are non-renewable resources, its onshore recoverable reserves arediminishing, but its demand is growing sharply. In response to the increasingly tense energysituation, humans have begun to exploit the offshore oil. The Semi Submersible DrillingPlatform for offshore drilling equipment to work normally.Deep-sea drilling, the platform will generate heaving motion which affected by waves，wind and ocean current. It harm to the drilling efficiency and quality, reduce the bit life.Therefore, we need to carry out heave compensation to drill column, in order to make themouth of the well drill string relative to the bottom displacement remain the same, thus stablebit pressure, achieve the goal that constant drilling pressure. Through the analyses andresearch of the heave compensation principle and the existing heave compensation device. Putforward the scheme that double servo winch is used to implement the drill string heavecompensation. According to the relationship between the elastic deformation of the drill stringand the weight on bit, use hook tension sensor testing tension signals，use servo motor drivenwinch which has big start torque, quick response speed of active heave compensation. Andaccording to the plan, design a set of heave compensation simulation experiment device.Offshore oil drilling simulator automatic heave compensation, made up of two partswhich are the mechanical part and monitoring system. Mechanical part including hoistingsystem, top drive, he waves simulation device, servo drive winch compensation device, drillpipe model loading device, etc; Cam mechanism to make the platform produces heavemovement up and down, drive the load drill pipe produce displacement, result in the load drillpipe inested spring the length change and the hook tension change. PLC compares the hooktension sensor signal with the given value, convert the result to electrical signal and output tothe servo motor, then adjust steering and speed of winch real-time, stabilize hook tension,realize automatic compensate and the wave interference can achieve dynamic coordinationcontrol system adopts the Profibus-DP technology, and through the King view to realizevisualization of the interface operation. This device meet the purpose that constant drillingpressure.