In the autumn of 2015, Tarr Ltd contacted Zolmat Bt requesting that the protective pipe of their optical cable between Paks and Géderlak, necessary for a communication network development, be installed under the river basin of the Danube for lack of a nearby bridge…
We installed a protective pipe for their optical cable necessary for a communication network development under the river basin of the Danube with directional drilling.
Local circumstances presented the implementation with challenges such as mobilisation within municipal boundaries, a planned borehole into great depths in a hard sandstone layer, the restricted options for contact with the outgoing end, and the challenging deadline.
A borehole planned to go deep does not allow for the use of „walk-over” type radio probes; furthermore, reception of any signals and the autumn fog, sometimes persisting for days, restricted our options of directing the drilling from a boat. The solution to these issues was the cutting-edge gyro-compass drilling control system, since this cable probe remains unaffected by all external circumstances such as interference or depth, and it doesn’t even need a valuation field.
By using the gyro-compass control system, theoretically even drilling down to 5,000 metres can be accomplished.
The hard sandstone layer was quickly “eaten up” by a drilling engine with a gear suitable for the transport capacity of a betonite pump, considering that the 710 metres of the entire borehole was drilled in less than 4 working days. (The drilling engine is an equipment that transforms betonite flow through a row of blades into a rotating motion, where the drill tip can be directly attached to the front.)
The amount of bentonite needed for the continuous cleaning of this rather long borehole was reduced to its minimum by recycling. This equipment separates the extruded sand and soil from the still usable drilling mud by a row of sieves. The efficiency of this system has a great impact even in an average case of drilling, let alone here where the drilling engine required extra attention for any quartz (sand) particles may erode the blades of the drilling engine, damaging the equipment in a matter of days.