Downhole fluid flow control device

A method of operating a fluid flow control device, the method comprising the steps of:

• (i) providing a fluid flow control device for a downhole apparatus, the device comprising:
• a body portion comprising a first fluid flow port and a second fluid flow port;
• a fluid flow path from the first fluid flow port to the second fluid flow port;
• and
• a valve member located in the fluid flow path and configured to be movable from a first, closed position in which the fluid flow path is blocked by the valve member, and a second, open position in which the fluid flow path is open;
• a trigger mechanism operable, by moving a trigger member from a first position to a second position, to convert the valve member from a secured state, in which the valve member cannot be moved, and an unsecured state, in which the valve member can be moved;
• wherein the valve member is configured to be movable from the first, closed position to the second, open position in response to a valve pressure cycle comprising:
• application of a positive differential pressure from the first flow port to the second flow port;
• and
• removal of the positive differential pressure;
• wherein the trigger member is movable from the first trigger position to the second trigger position in response to a trigger pressure cycle;
• (ii) arranging the first fluid flow port to receive fluid from a source of fluid;
• (iii) arranging the second fluid flow port to receive fluid from another source of fluid;
• (iv) applying the trigger pressure cycle to move the trigger member from the first trigger position to the second trigger position, to convert the valve member to the unsecured state;
• and
• (v) applying the valve pressure cycle to the valve member to move the valve member from the first, closed position to the second, open position.

A method of controlling the flow of fluid from a first region of a downhole apparatus to a second region, the method comprising the steps of:

• (i) providing a downhole apparatus comprising a fluid flow control device for a downhole apparatus, the device comprising:
• a body portion comprising a first fluid flow port and a second fluid flow port;
• a fluid flow path from the first fluid flow port to the second fluid flow port;
• and
• a valve member located in the fluid flow path and configured to be movable from a first, closed position in which the fluid flow path is blocked by the valve member, and a second, open position in which the fluid flow path is open;
• a trigger mechanism operable, by moving a trigger member from a first position to a second position, to convert the valve member from a secured state, in which the valve member cannot be moved, and an unsecured state, in which the valve member can be moved;
• wherein the valve member is configured to be movable from the first, closed position to the second, open position in response to a valve pressure cycle comprising:
• application of a positive differential pressure from the first flow port to the second flow port;
• and
• removal of the positive differential pressure;
• wherein the trigger member is movable from the first trigger position to the second trigger position in response to a trigger pressure cycle;
• (ii) arranging the first fluid flow port to receive fluid from a first region of the downhole apparatus;
• (iii) arranging the second fluid flow port to receive fluid from a second region of the downhole apparatus;
• (iv) applying the trigger pressure cycle to move the trigger member from the first trigger position to the second trigger position, to convert the valve member to the unsecured state;
• and
• (v) applying the valve pressure cycle to the valve member to move the valve member from the first, closed position to the second, open position.