The Haute-Sorne Project planned to drill in 2017 (GVL-1) the first of a 2-well geothermal doublet connected through an EGS. Water was intended to be circulated between the two wells, in a closed-loop system used for power generation. GVL-1 wanted to prove the feasibility of the Geo Energie Suisse downhole heat exchanger concept.
GVL-1 was planned to be drilled to a final vertical depth of 5 000 m. The final bottom hole static temperature (BHST) must be a minimum of 170°C. The well should have been drilled vertically until the top of the granite basement would have been reached and steered to intersect a maximum number of natural fissures and deviated to 55° from vertical.
The injection/production drain was not planned to be cased. The open hole drained should have been sectioned with a completion string using water swelling elastomer and slickline operated mechanical sleeves. The intended completion design would have called for 30 individual sections spread over a 1 500 m long drain. Each section should have been stimulated independently by injecting defined volumes of fresh water, according to a pumping sequence. An extensive seismic monitoring programme was planned, that would have taken place before, during and after the drilling, completion and stimulation operations.
The tense in above text has been adapted to reflect the originally intended procedure. None of the activities described have been carried out yet.