Abstract: Apparatus and method are provided for select-firing of perorating guns or activating other equipment in a well, such as a bridge plug. Double-pole double-throw electronic relays, used along with diodes that block voltage below a selected level, are used to control access of positive or negative voltages to blasting caps. Firing of a blasting cap causes an open circuit across the blasting cap and shifting of a relay. Alternate application of negative and positive voltages allows activation of multiple devices in a well.

Abstract: A downhole release tool for use in conjunction with multiple select-fire perforating guns and a method for electronically actuating the release tool using either positive or negative control voltage. In a preferred embodiment, the release tool employs operating circuitry that allows actuation of the release tool by either a positive or a negative voltage at an absolute magnitude greater than the absolute magnitude of positive or negative voltages used to arm or fire the perforating guns.

Abstract: Apparatus and method are provided for selectively firing apparatus in a well when the apparatus is fired by an electrical voltage and produces light upon firing. A photoresistor or other device changes in an electrical property when the light from firing of a section of the apparatus impinges on the photoresistor or other electronic device. The change in electrical property shifts the state of a relay such that the following section of the device can be fired with a voltage of the opposite polarity to that used in firing the preceding section. A test and resetting apparatus for the select-fire apparatus is also provided.