Nicholls Countryside Construction

Nicholls Countryside Construction

Geodrilling International - Installation of Closed-loop Borehole Probes


Courtesy of Nicholls Countryside Construction

The installation of closed-loop borehole probes is a challenge on almost any project. With many domestic clients requiring a large meterage of borehole to be installed in a small site, Nicholls Boreholes has found that the traditional manual installation of closed-loop borehole probes is no longer a safe or acceptable option.

The company has developed the Loop Feeder, a hydraulically-driven, robustly designed solution for the safe and efficient installation of borehole probes.

Although initially designed to meet the needs of its own drillers, Nicholls Boreholes identified a gap in the market for such a machine and has developed a system that will integrate seamlessly into the existing hydraulic circuits and controls on many drill rigs, from a variety of manufacturers.

The problem

Any driller with experience in closedloop installation will recognise the manual installation of borehole probes as one of the most tiring, and perhaps one of the most dangerous parts of the job.

The process often involves the entire drill crew, inevitably at the end of a full day of drilling, trying to push the geothermal probe through the drilling fluid to depth in the borehole.

As the probe goes deeper, it becomes more buoyant. Therefore, the deeper the installed depth, the harder the installation becomes. Furthermore, a geothermal driller's worst nightmare would be if, having started to run the borehole probe, it does not meet the required depth for the project.

The manual extraction of the probe is almost harder than the installation since it has to be lifted rather than allowed to sink to a depth, where the buoyancy of the probe equals its weight. With the health and safety of its employees paramount, Nicholls Boreholes, required an alternative installation and removal method.

How is it used

The Loop Feeder is a patented and CE-marked, mechanical, hydraulically driven machine, which assists with the insertion and extraction of geothermal borehole probes and grouting tremie into pre-drilled boreholes.

The feeder is clamped into the top jaw' of a geothermal drilling rig and attached hydraulically to the existing rig controls. It then uses the power from the drilling rig to operate. The Loop Feeder i~ compatible with the vast majority of modern drilling rigs. Measuring just 1,000mm x SOOmmx 270mm and weighing 80kg, the machine is easy to transport.

The Loop Feeder carries many benefits, both for the drillers on the rigs and the drilling company as a whole. By using the Loop Feeder, drillers no longer have to blow the water out of the pre-tested probes to pull them out manually.

They can simply reverse the Loop Feeder and remove the probe without strain.

Having a more reliable method of installing probes to depth reduces the likelihood of having to redrill the borehole, which greatly improves efficiency on site.

Furthermore, the installation of probes with the Loop Feeder requires fewer staff, presenting an additional cost saving. Nicholls Boreholes has found that on airdrilled holes, where there is a significant depth to the watertable, a greater level of control can be achieved when inserting borehole probes with the Loop Feeder.

This will stop the probe from heading uncontrollably to the bottom of the borehole, preventing damage to the probe and reducing any risk to the operatives.

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