Safety valve control system and method of use

A control system for controlling fluid flow through a flow line at a wellsite, the control system comprising:

• a fluid supply;
• a first fluid line in fluid communication with the fluid supply;
• a pump in fluid communication with the first fluid line and configured to pump fluid from the fluid supply to one or more wellheads through the first fluid line;
• a second fluid line in fluid communication with the first fluid line at a location downstream of the pump and configured to relieve fluid from the first fluid line;
• a safety valve in-line with the second fluid line and normally maintained in a closed position to close fluid flow through the second fluid line;
• a valve actuator configured to move the safety valve into the closed position by fluid supplied to the valve actuator and configured to move the safety valve into an open position by a biasing member disposed in the valve actuator;
• an electronic controller assembly programmed with a predetermined condition and configured to receive a signal from a transducer connected to the first fluid line, wherein the signal corresponds to a measured physical property;
• a valve assembly in communication with the controller assembly;
• and
• a fluid drive assembly in communication with the controller assembly, wherein the controller assembly is operable to actuate the fluid drive assembly to supply fluid to the valve actuator to move the safety valve into the closed position, and wherein the controller assembly is operable to actuate the valve assembly in response to a comparison of the measured physical property to the predetermined condition to release fluid from the valve actuator so that the biasing member moves the safety valve into the open position, forces fluid out of the valve actuator, and thereby opens fluid flow through the second fluid line to relieve fluid from the first fluid line.

A method for controlling fluid flow through a flow line at a wellsite, the method comprising:

• providing a control system comprising:
• a fluid supply;
• a first fluid line in fluid communication with the fluid supply;
• a pump in fluid communication with the first fluid line and configured to pump fluid from the fluid supply to one or more wellheads through the first fluid line;
• a second fluid line in fluid communication with the first fluid line at a location downstream of the pump and configured to relieve fluid from the first fluid line;
• a safety valve in-line with the second fluid line,
• a valve actuator configured to actuate the safety valve,
• an electronic controller assembly,
• a fluid drive assembly, and
• a valve assembly;
• supplying fluid to the valve actuator using the fluid drive assembly to actuate the valve actuator to move the safety valve into a closed position;
• maintaining the safety valve in the closed position to close fluid flow through the second fluid line;
• monitoring a physical property in the first fluid line using the controller assembly;
• and
• actuating the valve assembly using the controller assembly to release fluid from the valve actuator so that a biasing member disposed in the valve actuator moves the safety valve into an open position, forces fluid out of the valve actuator, and thereby opens fluid flow through the second fluid line based upon a comparison of the monitored physical property to a predetermined condition to relieve fluid from the first fluid line.