Tractor Communication/Control and Select Fire Perforating Switch Simulations

Abstract

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. 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. The state machine need not return a signal including a unique identifier.

What is claimed is: 
     
         1 . Apparatus for controlling one or more devices in a wellbore comprising:
 a surface computer;   a surface controller;   one or more control units connected to one or more devices, the control units being adapted for bi-directional communication with said surface controller over a cable, each said control unit comprising a state machine for identifying the status of the control unit, the surface controller being adapted to send commands to the control units;   characterized in that;   the state machine of each control unit is adapted to identify one or more valid commands for each status of the control unit;   the control units each being adapted to verify whether a command is valid for the status of the control unit, send an error message to the surface controller if the command is not valid for the status of the control unit, perform the command and send an uplink message to the surface controller comprising the status of the control unit if the command is valid for the status of the control unit; and   the surface controller being adapted to identify the relative position of the devices within the tool string by tracking the commands and uplink messages and remove power to the control units if it receives an error message or if does not receive an uplink message after the command is sent.   
     
     
         2 . The apparatus of  claim 1  wherein said surface computer communicates with the surface controller via wireless connection. 
     
     
         3 . The apparatus of  claim 1  wherein said surface computer and said surface controller selectively controls said control units using a sequence of commands. 
     
     
         4 . The apparatus of  claim 1  wherein each said control unit is adapted for communicating status information to said surface computer over-a cable. 
     
     
         5 . The apparatus of  claim 1  wherein the control units are electrically connected in series. 
     
     
         6 . The apparatus of  claim 1  wherein said control units access one or more than one of the following: a tractor motor; sensors for monitoring one or more of the parameters of tractor RPM, temperature, voltage, and/or current either at the surface or at the surface while tractoring; a mechanism for releasing a tractor from said cable; a mechanism for releasing one or more tools in a tool string; a unit containing sensors for monitoring downhole conditions including temperature, pressure, voltage, current, inclination, rotation, and/or acceleration; a well logging tool; an auxiliary tractor tool; a device for blocking voltage; an explosive initiator; a perforating gun including an explosive initiator; and/or a setting tool including an explosive initiator. 
     
     
         7 . The apparatus of  claim 1  wherein said control unit comprises one or more transistor switches, form-C switches, latching relays, or motorized piston switches. 
     
     
         8 . The apparatus of  claim 1  additionally comprising voltage-protected circuitry for controlling one or more switches in said control unit. 
     
     
         9 . The apparatus of  claim 8  wherein said voltage-protected circuitry comprises a shunting device and a fuse element. 
     
     
         10 . The apparatus of  claim 8  further comprising a circuit containing a transformer or one or more diodes, Zener diodes, triacs, or P- or N-channel FETs. 
     
     
         11 . The apparatus of  claim 1  wherein the state machine of each of said control units is provided with a pre-assigned identifier for each said control unit. 
     
     
         12 . The apparatus of  claim 11  wherein the pre-assigned identifier is contained in either a downlink, an uplink, or both downlink and uplink communications. 
     
     
         13 . An explosive initiator integrated with a control unit comprising:
 means for receiving a signal from a cable to which the explosive initiator is electrically connected;   characterized in that the initiator further comprises:   a microcontroller including a state machine for validating a signal from said signal receiving means;   a switch responsive to an output from said microcontroller when a signal is validated by the state machine; and   an explosive initiator connected to said switch.   
     
     
         14 . The explosive initiator of  claim 13  additionally comprising a switch for passing power, communication signals, or power and communication signals, to a device connected to the cable. 
     
     
         15 . The explosive initiator of  claim 13  wherein said switch is comprised of an explosive initiator switch and a wireline switch. 
     
     
         16 . The explosive initiator of  claim 13  wherein the state machine is provided with a pre-assigned identifier. 
     
     
         17 . An apparatus for checking the function of one or more downhole tools before lowering the tools into a wellbore comprising:
 a pre-check controller;   electrical connections between said pre-check controller and one or more downhole tools to be lowered into a wellbore; and   one or more control units mounted on each downhole tool adapted for bi-directional communication with said pre-check controller, each said control unit comprising a state machine for identifying the status of each said control unit, said pre-check controller being adapted to send a plurality of commands to the respective control units;   characterized in that;   the state machine of each control unit is adapted to identify one or more valid commands for each state of the control unit;   the control units each being adapted to verify whether a command is valid for the state of the control unit, send an error message to the pre-check controller if the command is not valid for the state of the control unit, perform the command and send an uplink message to the pre-check controller comprising the state of the control unit if the command is valid for the state of the control unit; and   the pre-check controller being adapted to identify the relative position of the devices within the tool string by tracking the commands and uplink messages and remove power to the control units if it receives an error message or if it does not receive an uplink message after the command is sent.   
     
     
         18 . The apparatus of  claim 17  additionally comprising a surface computer, said surface computer communicating with said pre-check controller via either a cable, a wireless connection, or a combination of cable and wireless connection. 
     
     
         19 . The apparatus of  claim 17  wherein the state machine of each of said control units is provided with a pre-assigned identifier for each said control unit. 
     
     
         20 . The apparatus of  claim 19  wherein the pre-assigned identifier is contained in either a downlink, an uplink, or both downlink and uplink communications. 
     
     
         21 . The apparatus of  claim 17  wherein the switches controlled by the state machine are located on either a perforating gun or setting tool.