Spec Sheet:

Precision Mechanical Applications

Switch Sub


Conveyance of Seismic geophone arrays 

The Switch Sub is a multi-conductor device that enables the tractor conveyance of non-rigid downhole seismic geophone arrays into highly deviated and horizontal wells. The Switch Sub is positioned at the top of the toolstring (between the cable head and geophone array) and the PowerTrac® tractor is placed below the seismic tools.

The device has two positions controllable via surface command:

  • In tractor mode, it connects the wireline to a spare feedthrough in the seismic toolstring to transmit power to the tractor.
  • In logging mode, the wireline is connected directly to the seismic toolstring and the tractor below is isolated.
  • In operation, the PowerTrac® tractor tows the seismic toolstring to the required station acquisition depth. Surface commands are then sent to the sub to switch from tractor conveyance mode to seismic data acquisition mode.


  • Downhole seismic array acquisition in highly deviated and horizontal wells



  • Placed between cable head and logging tools
  • Surface controlled
  • PowerTrac® placed below the tools



  • High quality borehole seismic acquisition in deviated or horizontal wells


Service Name

Switch Sub 371

Tool body outer diameter

3.15 inches/80.0mm


2.50 ft./0.76m

Minimum restriction ID

3.28 inches/83.3mm

Pressure rating

15,000 psi/1,034 bar

Temperature rating

177 °C/350 °F

Electrical feed through


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