Tractor Communication/Control and Select Fire Perforating Switch Simulations

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.

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.