EBFire® switches are designed to allow multiple, independently fired, perforating guns in a single trip. They are disposable and polarity discriminating which allows sequential firing control. Two main types of switches are available depending on the nature of perforating operations being conducted. They are the pressure switch and dual diode switch.
Pressure switches work by utilizing pressure shock waves generated by the detonation of perforating guns. The shock wave actuates an arming piston by pushing it to make contact with the proceeding detonator. A diode is connected to each switch such that all the guns do not initiate at once – only one gun will initiate per firing sequence. Therefore positive (+) and negative (-) pressure switches are available to control firing selectivity. It is very important that they are correctly placed within the gun string such that each gun is selected and fired at the correct depth.
This type of switch can only be used in hollow steel carrier perforating guns. Any length of gun and any number of switches can be used at any one time, the only limitations being rig height, surface equipment setup and wireline cable strength.
Dual Diode Switch
The dual diode switch is designed such that no outside influence is required to fire either of the perforating guns. This allows a setting tool to be fired below a perforating gun, fire the second gun in the string in the event of rathole issues, or if there are problems with the lower gun.
Two diodes are used inside the switch to discriminate between a positive (+) firing and negative (-) firing. As the dual diode switch uses a hardwired circuit, it is always in contact (and armed) with both the upper and lower detonator. Only one dual diode can be used in a gunstring and it must be placed between the first two detonators fired in the gunstring.
If more than two guns are used, then the dual diode must be placed between the first two detonators to be fired and pressure switches used between the upper guns in the gunstring.