US Patent 10107052 Control of hydraulic power flowrate for managed pressure drilling

An assembly uses a choke to control flow of wellbore fluid in a drilling system. A controller operatively coupled to the choke can control opening/closing of the choke with hydraulic power and an actuator. The control operates the opening/closing of the choke with a choke control value to control a parameter in the drilling system, such as pressure or flow. The control measure a time for the choke to at least reach a position toward a full open/closed position during a full opening/closing operation and calculates a current opening/closing speed of the choke. When this current speed is compared to a previously stored speed, the control adjusts the choke control value for the choke based on any difference.