Flow control system and method for use in a wellbore

1. A system for use in a wellbore, comprising:

a perforating gun string having a large internal flow path;

a packer mounted to the perforating gun string; and

a valve system mounted to the perforating gun string to control flow between an interior and an exterior of the perforating gun string via at least one radial port extending through a wall of the perforating gun string, the valve system comprising a valve controlled by an activation device responsive to a pressure and time signal, the activation device having electronics to detect both pressure inputs and the timing of the pressure inputs for matching against a predetermined signature, the activation device responding by selectively controlling an activation port that may be opened to enable actuation of the valve by hydrostatic pressure in the wellbore, the valve system being located in a perforating gun string housing so the valve system remains outside of the large internal flow path when actuated between open and closed states, the activation device being mounted in a slot within an outer surface of the perforating gun string housing to maintain the large internal flow path.

2. The system as recited in claim 1 , wherein the pressure and time signal comprises low pressure pulse signals sent downhole according to a specific time sequence.

3. The system as recited in claim 1 , wherein the valve is maintained in an open position when the valve system is moved downhole into the wellbore.

4. The system as recited in claim 3 , wherein the valve comprises a retention mechanism to hold the valve in a shifted position once actuated to the shifted position.

5. The system as recited in claim 1 , wherein the valve system further comprises a second valve and a second activation device.

6. The system as recited in claim 5 , wherein the valve is maintained in an open position and the second valve is maintained in a closed position when the valve system is moved downhole into the wellbore.

7. The system as recited in claim 1 , wherein the valve system further comprises a retention mechanism to maintain the valve in a desired state during deployment into the wellbore.

8. The system as recited in claim 5 , wherein the pressure and time signal comprises at least two unique pressure and time signals to enable independent control of the valve and the second valve.

9. A method of employing a perforating system, comprising:

coupling a perforating gun string to a valve system, the perforating gun string having a large internal flow path;

locating the valve system in a perforating gun string housing so the valve system remains outside of the large internal flow path when actuated between open and closed states;

moving the perforating gun string and the valve system to a desired location in wellbore;

detecting a predetermined signature of pressure inputs provided with a specific timing, wherein detecting is accomplished with an actuation device removably mounted in a housing slot along an exterior surface of the perforating gun string housing through which the large internal flow path extends, the housing slot being formed outside the large internal flow path to avoid restricting the large internal flow path; and

actuating the valve system upon detection of the predetermined signature by opening an activation port that actuates a valve of the valve system by hydrostatic pressure of the wellbore.

10. The method as recited in claim 9 , wherein actuating comprises opening or closing a valve of the valve system in response to a plurality of low pressure pulses applied according to a predetermined time sequence.

11. The method as recited in claim 9 , wherein actuating comprises actuating at least two valves via unique pressure and time signals.

12. The method as recited in claim 9 , wherein moving comprises running the perforating gun string and the valve system downhole with the valve open between the wellbore and an interior of the gun string.

13. A method of employing a perforating system, comprising:

coupling a perforating gun string to a valve system, the perforating gun string having a large internal flow path;

locating the valve system in a perforating gun string housing so the valve system remains outside of the large internal flow path when actuated between open and closed states;

moving the perforating gun string and the valve system to a desired location in wellbore, wherein moving comprises running the perforating gun string and the valve system downhole with the valve open between the wellbore and an interior of the gun string;

detecting a predetermined signature of pressure inputs provided with a specific timing, wherein detecting is accomplished with an actuation device removably mounted in a housing slot of a housing through which the large internal flow path extends, the housing slot being formed outside the large internal flow path to avoid restricting the large internal flow path;

actuating the valve system upon detection of the predetermined signature by opening an activation port that actuates a valve of the valve system by hydrostatic pressure of the wellbore

pumping a cushion fluid downhole through the perforating gun string and out into the wellbore through the valve;

sealing a region of the wellbore with a packer;

closing the valve via the pressure and time signal to trap a desired pressure in the region; and

firing a perforating gun of the perforating gun string.