Patent ID: 9175528
Filing Date: 2015-11-03
Classification: E21B

Abstract:
1. A system for lifting drilling mud from a subsea wellbore comprising: a mud pump in fluid communication with a flow of mud from the subsea wellbore; a working fluid supply line in communication with the mud pump and having a supply of working fluid; a working fluid discharge line in communication with the mud pump and having a flow of working fluid discharged from the mud pump, the working fluid discharge line having a flow meter and a control valve; and a pressure control circuit having a pressurization line at an upstream end in communication with the working fluid supply line and a bypass line at a downstream end in selective communication with the working fluid discharge line at a point upstream of the control valve; the control valve adjustable in response to a flow rate of the working fluid as measured by the flow meter of the working fluid discharge line to reduce flow through the control valve and increase pressure in the working fluid discharge line.