Addressable switch assembly for wellbore systems and method

1. A method for controlling a target switch assembly in a chain of switch assemblies, the method comprising:

distributing the chain of switch assemblies in a wellbore;

placing a controller at a head of the wellbore;

making a first decision, at the controller, to actuate a corresponding detonator of the target switch assembly;

transmitting, from the controller to the target switch assembly, a fire command to activate the corresponding detonator; and

making a second decision, locally, at the target switch assembly, whether or not to activate the detonator, after the fire command from the controller is received, based on whether or not a voltage measured by the target switch assembly at the target switch assembly is larger than a threshold voltage.

2. The method of claim 1 , wherein each switch assembly of the chain of switch assemblies has a unique digital address.

3. The method of claim 1 , wherein each switch assembly of the chain of switch assemblies includes a detonator switch and a thru-line switch.

4. The method of claim 3 , wherein the detonator switch activates the corresponding detonator and the thru-line switch allows a voltage in a thru-line to pass from the target switch assembly to an adjacent switch assembly.

5. The method of claim 1 , wherein a thru-line extends from the controller to the target switch assembly and the fire command is transmitted along the thru-line.

6. The method of claim 1 , further comprising:

measuring the voltage, at the target switch assembly, of a thru-line that extends from the controller to the target switch assembly.

7. The method of claim 6 , further comprising:

when the measured voltage is larger than the threshold voltage, actuating the corresponding detonator.

8. The method of claim 1 , further comprising:

starting a first timer upon receiving the fire command,

wherein the first timer counts a given first time period.

9. The method of claim 8 , further comprising:

measuring the voltage, at the target switch assembly, of a thru-line that extends from the controller to the target switch assembly; and

when the measured voltage is larger than the threshold voltage, and when the first time period has not lapsed, actuating the corresponding detonator.

10. The method of claim 9 , further comprising:

starting a second timer when the detonator is actuated.

11. The method of claim 10 , further comprising:

switching off a detonator switch when a second time period of the second timer has elapsed.

12. The method of claim 8 , further comprising:

measuring the voltage, at the switch assembly, of a thru-line that extends from the controller to the target switch assembly; and

when the measured voltage is larger than the threshold voltage, but the first time period has lapsed, not actuating the corresponding detonator.

13. The method of claim 8 , further comprising:

measuring the voltage, at the target switch assembly, of a thru-line that extends from the controller to the target switch assembly; and

when the measured voltage is not larger than the threshold voltage, not actuating the corresponding detonator.

14. The method of claim 8 , further comprising:

starting a second timer upon receiving the fire command,

wherein the second timer counts a given second time period, which is shorter than the first time period.

15. The method of claim 14 , further comprising:

sending status information from the target switch assembly to the controller when the second time period has elapsed.

16. The method of claim 1 , further comprising:

inserting into the fire command, at the controller, a digital address of the target switch assembly.