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 1 Details of the geological and geophysical data sets available for the granitic basement of the GRT-1 and GRT-2 wells

	Name	Depth (MD) GRT-1	Depth (MD) GRT-2	Unit	Vertical resolution–Horizontal resolution
Mud logs	Cuttings	2215–2580 m, 122 samples	2480–3196 m, 239 samples	No unit	Sampled each 3 m in-depth
	CEC	No CEC measurements in GRT-1	2503–3151 m, 8 samples	meq/100 g	CEC measurements were performed on crushed cutting samples
	Calcite	2215–2580 m	2480–3196 m	m³/m³ (expressed in %)	Calcimeter measurements were performed on crushed cutting samples
	Mud losses	2215–2580 m	2480–3196 m	m³/h	Driller observations
	Rate of penetration (ROP)	2215–2580 m	2480–3196 m	m/h	50 cm
Geophysical logs	Gamma ray (GR)	2215–2570 m	2480–3196 m	gAPI	15 cm
	Hole diameter	2215–2580 m	2480–3008 m	Inches	15 cm 60°
	BoreHole image	2480–2865 m	2480–2865 m		1 cm 2°
	Resistivity	No resistivity log in GRT-1	2480–3196 m	ohm m	15 cm
	Porosity	2215–2577 m	2480–3196 m	m³/m³	15 cm depth of investigation: several cm (flushed zone)
	Density	2215–2580 m	2480–3196 m	g/cm	15 cm
	Temperature	2215–2470 m	2480–3169 m	°C	GRT-1 = 20 cm GRT-2 = 50 cm

The first column presents the type of data; columns two and three present the measured depth intervals in the two open-hole sections. The fourth column presents the units of the data, and the fifth column presents the resolution of the data according to the log acquisition resolution, both vertically and horizontally (in italic letters)