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Table 2 Fracture zones observed through the stratigraphic analysis (log cutting) analysed with the mud logging and on the seismic profile

From: New stratigraphic interpretation of the Soultz-sous-Forêts 30-year-old geothermal wells calibrated on the recent one from Rittershoffen (Upper Rhine Graben, France)

Depth
  GPK-1
 639 m Mud logging: millimetre opened fractures with oil (also observed on the cores) at around 635 m
Log cutting: Marnes à Ovoïdes reduced in comparison with Rittershoffen (19 m on the 44 m expected)
Seismic profile: nothing observed
Fracture zone with 26 m vertical apparent offset interpreted as a fault
 1002 m Mud logging: millimetre to centimetre fractures filled with calcite, quartz, oil and bitumen, anomalies in caliper, neutron porosity and ROP, decrease of density, increase of porosity and temperature anomalies
Log cutting: Marnes Bariolées absent, top of the complex constituted by the complex of DolomiesCalcaires OndulésCouches à Myacites and base of the Dolomie à Lingules affected
Seismic profile: nothing observed
Fracture zone with 60.5 m cumulated offset interpreted as a fault
  GPK-2
 686 m Mud logging: gas anomalies around 675 m
Log cutting: Marnes à Ovoïdes reduced in comparison with Rittershoffen (22,5 m instead of 44 m expected)
Seismic profile: nothing observed
Fracture zone with 21.5 m vertical apparent offset interpreted as a fault
 793 m Mud logging: positive ROP anomaly, decrease in gas log
Log cutting: most of Keuper’s units are absent: Argiles de LevalloisGrès du Rhétien; Marnes Irisées moyennes; Argiles de Chanville; Dolomie en DallesMarnes Irisées inférieuresGrès à Roseaux
Seismic profile: nothing observed
Fracture zone with 136 m vertical apparent offset interpreted as a fault
 911 m Mud logging: big caliper and gas anomalies, mud losses which involves permeability
Log cutting: one half of the Calcaire à Entroques is absent (5 m instead of 10 m expected)
Seismic profile: nothing observed
Fracture zone with 5 m vertical apparent offset interpreted as a fault
 1064 m Mud logging: caliper and gas anomalies
Log cutting: facture zone with conglomeratic base of the Couches Intermédiaires absent and the top of the Couches de Karlstal affected
Seismic profile: nothing observed
Fracture zone with 32 m vertical apparent offset interpreted as a fault