On December 13th, 2017, the first subhorizontal geothermal well, designed and supervised by GPC IP, has been completed on the Paris suburban Cachan site for its customer DALKIA (EDF Group).
The well architecture is a World premiere in geothermal engineering as it achieves a 1 001 m long, 87° slanted, 8"1/2 openhole drain in the Dogger/Bathonian, Mid Jurassic, oolithic limestone, target reservoir, at a 1 550 m true vertical depth.
The concept, first published in February 2011(1) at the Stanford Geothermal Engineering Workshop, proved rewarding, further to well tests, evidencing a 450 m3/hr nominal discharge and a 16 MWth rated capacity.
This well will be further replicated by an injection well of similar architecture.
The new doublet, managed by a DALKIA/City of Cachan JV (DALKIA operator) will replace two, 34 year old, existing geothermal district heating doublets.
Pierre UNGEMACH & Miklos ANTICS
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