FAIL-SAFE CONTROL OF SAFETY VALVE FOR DEEP INSTALLATION WITH TWO CONTROL LINES Russian patent published in 2013 - IPC E21B34/10 F15B15/02 

FIELD: oil and gas industry.

SUBSTANCE: hydraulic control system for an underground safety valve has control lines hydraulically interconnected with the valve. The first control line transmits hydraulic pressure bringing the valve into action, and the other control line transmits hydraulic pressure compensating hydrostatic pressure corresponding to the first control line. The control controls hydraulic interconnected between two control lines. The control prevents hydraulic interconnected from the first one to a balancing control line whole tightness of the second line is being maintained. When the second line fails, the safety valve can fail in an open position. In this case, the control provides relief of hydraulic pressure from the first line to the second line.

EFFECT: change-over of the safety valve to a closed position at failure of the first line and provision of possible reloading of the second line at recovery of its tightness.

29 cl, 10 dwg