Clay mineral occurrences in volcanic and granitic geothermal - - PowerPoint PPT Presentation

Clay mineral occurrences in volcanic and granitic geothermal contexts: signatures of high temperature fluid circulations in natural permeable fractures

Genter Albert1, Patrier-Mas P.², Beaufort D.², Dezayes Ch.1, Guisseau D.2, Ledesert B.3, Mas A.2, Traineau H.4

1BRGM Orléans,²Hydrasa Poitiers, 3Univ. Cergy-Pontoise, 4CFG Services

Department of Geothermal Energy (GTH) ENGINE Workshop, Volterra (Italy), April 2-4, 2007

ENGINE Workshop, Volterra (Italy), April 2-4, 2007 Department of Geothermal Energy (GTH)

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Objective

• Relationships

between clays, natural fractures and permeability

• Volcanic area of Bouillante (Guadeloupe))
• Granite basement of the EGS Soultz wells (France)

ENGINE Workshop, Volterra (Italy), April 2-4, 2007 Department of Geothermal Energy (GTH)

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Hydrothermal alteration at Bouillante

Smectite Chlorite Illite Geothermal Field data Well BO-6

ENGINE Workshop, Volterra (Italy), April 2-4, 2007 Department of Geothermal Energy (GTH)

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Clays-fractures-permeability at Soultz

3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498

F-ma F-ma F-ma F-ma

3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 Depth (m) UBI Amplitude UBI Transit Time Facies

100 200

Gamma Ray GAPI

1.70 2.20 2.70

Bulk density g/cm3

0.04 0.08

Potassium %

1 3

Uranium ppm

10 25 40

Thorium ppm

45 60 75

DT Comp µs/feet

75 100 125

DT Shear µs/feet

6.25 9.25 12.25

Caliper inch

200 300Cross Section Area cm2 45 90

Dip

• 0.5

0.5

Production log 8l/s

2

Injection log 18 l/s Permeable fracture Depth (m)

Damaged fracture zone Clays: illite + tosudite Secondary quartz deposition High porosity Brines 100g/L

Thin section - Fracture Illite, calcite, hematite Well GPK1, 3500 m