The third test drilling on the Balmatt site was successfully completed at the end of July 2018 to a record length of 4,905 m. The pumping test of borehole 3 has shown that the underground limestone reservoir is much more complex than originally calculated.

The purpose of the third test drill was to broach the same type of Calcerous Carboniferous strata, which has shown great geothermal productivity in the first drill. This productivity is caused by natural currents in the deep subsurface. The third borehole has now shown that the flow paths are different than initially calculated. That is why the VITO experts have carried out a new seismic data acquisition campaign, from the Balmatt site to Mol-Donk. This time the sound waves were recorded with measuring devices hanging down in the third well. This method gives a much more accurate picture of the deep subsurface in comparison with the original seismic campaign from 2010, in which the registrations had to take place on the earth surface.

The researchers are now further analysing the seismic data to better understand the flow paths in the deep subsurface. If the results show where the zone is located, with identical reservoir properties as borehole 1, it can be seen whether the third borehole can be extended with a laterally drilled path. In that case, another derrick will be brought to the Balmatt site to drill into the new zone. To be continued.