Apparatus and methods for controlling and communicating with downhole devices

摘要

Apparatus and methods for controlling and communicating with one or more tools in a downhole tool string including a tractor, an auxiliary tractor tool, a logging tool, a safety sub, a release mechanism, a unit containing sensors for monitoring downhole conditions, a setting tool, and a perforating gun. Also provided are apparatus and methods for controlling and communicating with one or more perforating guns, release devices, and explosive devices in a string to be lowered into a wellbore. Control and communication are accomplished by sending signals from the surface to control switches in the control units on the tool, with redundant switches for safety, to state machines in the respective control units, “each state machine returning a signal verifying switch status to the surface. Control and power functions are accomplished with voltage of different polarities for safety.

主权项

1. A method of communicating with a switch unit located on a perforating gun, release device, or explosive device for lowering into a wellbore comprising the steps of:
sending a command to the switch unit; identifying the status of a switch with a state machine within the switch unit; identifying one or more valid commands for the status of the switch with the state machine; determining whether the command is valid for the status of the switch with the state machine; if the command is invalid, returning a signal comprising an error message from the switch unit at a current level in the range of from about 4 milliamps to about 15 milliamps; if the command is valid, controlling the position of the switch; and if the command is valid, returning a signal validating switch status from the switch unit at a current level in the range of from about 4 milliamps to about 15 milliamps.