2 1/8" MDT tractor

The MDT is a wireline-deployed system used to convey downhole tools into difficult well profiles. It is modular enabling a number of sections (actuators and drive arms/wheels) to be connected below the MDT electronics section, providing greater force to convey the tools along the well.

The electronics cartridge for the MDT contains a highly efficient (97%) electric motor that controls the clutch and motor assembly of the tool; it also houses tool telemetry boards.

Surface monitoring and control

Signals from the MDT and associated sensors are compressed downhole in the electronics cartridge for transmission to surface, enabling the logging engineer to monitor various tractor functions in real-time. There is also a surface-controlled switch mechanism, within the electronics cartridge, that isolates the tractor from its passenger tools during the logging survey.

Optimised for maximum tractor force

The drive arm and wheels of the actuator section are optimised to provide the maximum tractor force to drive the MDT and passenger toolstring combination along the well. They open when power is applied to the clutch and close when it is switched off. There is also a fail-safe mechanism automatically disengaging the clutch if power is lost - that completely closes the drive arm - enabling the tractor to be retrieved back to surface. The arms are available in different sizes to match the casings internal diameter and, in complex completions, each pair of arms can be selected for different casing sizes adding extra flexibility. Every tractor is temperature tested and qualified on a test track whilst pulling a heavy load.

Facilitating access to difficult areas

Low friction four arm centralizers and knuckle joints specifically designed to operate with the MDT can be included in the tool configuration to aid access in difficult areas of the well. CCL and head tension readings are also available with the MDT. These are used for depth control and over-pull indication respectively.

Versatile software

Seawell uses WEST software to plan MDT operations in highly deviated or horizontal wells. The software can be used to identify operational considerations such as optimum MDT configuration, the depth at which the MDT should be activated and plot the tractor and cable forces. WEST can be used as part of the pre-job planning and also in real-time during the logging operation.

Key features & benefits

• Helicopter transportable
• Low cost alternative to coiled tubing operations
• Integrated CCL and head tension measurements
• Modular drive sections
• WEST simulation software available to aid pre-job planning
• Proven record of success and reliability
• Pure electro-mechanical design, no hydraulics issues
• Energy efficient, can run on 7/32" mono-conductor cable
• Fully bi-directional
• Real time control and monitoring of downhole conditions (head tension, electronics temp, speed, etc).