Fully electric through the Netherlands: TERRA-JET DJ 66e in HDD operation

Over 250 meters for a new district heating pipeline

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In the Netherlands, the all-electric TERRA-JET DJ 66e HDD drilling rig was used for the trenchless installation of a district heating pipeline. The project involved a drilling distance of over 400 meters and the pullback of a pipeline with a diameter of over 315 mm. The combination of a challenging drilling path, precise steering, and a properly sized borehole placed high demands on the machine, tracking system, and drilling crew. At the same time, the project provided the ideal opportunity to demonstrate the performance of an all-electric drive concept under real-world job site conditions.

TERRA-JET DJ 66e – 30 tons of all-electric drilling power

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With the TERRA-JET DJ 66e, TERRA is consistently focusing on the electrification of high-performance HDD drilling rigs. The 30-ton rig operates entirely on electricity, combining high drilling performance with a modern, locally emission-free drive concept. With a thrust and pullback force of 300 kN, a maximum torque of 12,500 Nm, and a rotation speed of up to 230 rpm, the DJ 66e is designed for demanding and long HDD bores. The electric drive offers a decisive advantage, especially on job sites: the required power is available immediately and can be precisely controlled. At the same time, the machine operates significantly quieter than a comparable diesel-hydraulic drilling rig and produces no local exhaust emissions during electric operation. The project in the Netherlands thus demonstrated not only the machine's performance but also that electrification and heavy-duty HDD applications can go hand in hand.

Pilot bore with Brownline Gyro Steering Tool

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A key prerequisite for the successful completion of the more than 400-meter-long bore was the precise steering of the pilot hole. For this, the Brownline Gyro Steering Tool was used. Unlike classic walk-over tracking systems, this system operates based on gyro technology and does not rely on a magnetic field at the ground surface. The position and orientation of the drill head are determined during the drilling process and combined with the distance already drilled. This allows the actual path of the pilot bore to be continuously determined and the drill head to be steered precisely along the planned route. Brownline specifies an accuracy of 0.01° for inclination and 0.04° for azimuth for the Gyro Steering Tool. Since the system operates independently of magnetic fields, it is particularly suitable for longer and complex HDD bores as well as for projects where conventional tracking methods reach their limits. This made the high performance of the DJ 66e and the precise gyro-compass steering the perfect match during the pilot bore.

Step-by-step borehole enlargement

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After the successful completion of the pilot bore, the reaming process began. The initially relatively small pilot channel was expanded to the diameter required for the district heating pipeline in a single reaming pass. It was during this phase that the DJ 66e was able to demonstrate its power reserves. During reaming, high torque must be reliably transmitted to the drill string and the reamer, while sufficient pulling force must be available at the same time. With up to 12,500 Nm of torque and 300 kN of pullback force, the all-electric drilling rig has the necessary reserves for such demanding reaming work. In addition, up to 1,000 l/min of drilling fluid volume is available (externally).

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Ready for the district heating pipeline pullback

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Once the reaming work was complete, the district heating pipe was pulled through the entire drilled section. This meant the connection, spanning more than 400 meters, was completed entirely without the need for trenches. This project in the Netherlands demonstrates the potential that electric drive technology now offers for high-performance HDD applications. From the precise pilot bore using a gyro compass and the individual reaming stages to the final pipe pull, the machine, tracking technology, and drilling crew functioned as a perfectly synchronized system. For the TERRA-JET DJ 66e, this project marks another step toward a new generation of high-performance HDD drilling rigs: full drilling power – fully electric.