How do the geological and geophysical signatures of permeable fractures in granitic basement evolve after long periods of natural circulation? Insights from the Rittershoffen geothermal wells (France)

Geothermal Energy

Science – Society – Technology

Table 2 Structural analysis of the GRT-2 granitic basement with the caliper

GRT-2	Corrected caliper			Acoustic image logs			Accuracy
	Density (fract/m)	Dip direction		Density (fract/m)	Dip direction		Dip direction	dip
	Density (fract/m)	Set 1	Set 2	Density (fract/m)	Set 1	Set 2	Dip direction	dip
ZONE 1: 38 m (2196–2227 m TVD)	0.2	N274°E	N61°E	0.6	N263°E	N74°E	± 11°	± 5°
ZONE 2: 60 m (2360–2409 m TVD)	0.3	N272°E	N70°E	0.9	N265°E	N81°E	± 9°	± 13°
ZONE 3: 40 m (2472–2504 m TVD)	0.15	N52°E		No data			± 10	± 9°
ZONE 4: 40 m (2504–2535 m TVD)	0.17	N80°E		No data			± 10	± 9°

Comparison of the structural analyses and their accuracies as calculated from the caliper and acoustic image logs (zones 1 and 2). Structural analysis from caliper data only (zones 3 and 4)