Chemistry of a low temperature geothermal reservoir: The Triassic sandstone aquifer at Melleray, FR
The Triassic sandstone aquifer offers on a regional scale, a large potential for low-temperature geothermal exploitation in the Paris Basin. The Na-Cl water n the aquifer has highly variable mineralization (TDS = 4 to 110 g/l) and a wide range of temperature (50º to >100ºC). Chemical studies have been carried out on the Melleray site near Orléans, where a single wel was producing a Na-Cl geothermal water (TDS = 35 g/l) at a wellhead temperature of 72ºC to provide heat for greenhouses. The purpose of these studies is to understand the chemical phenomena occurring in the geothermal loop and to determine the treatment of the fluid and the exploitation procedures necessary for proper reinjection conditions to be achieved. During the tests performed after the drilling operations, chemical variations in the fluid were noticed between several producing zones in the aquifer. Daily geochemical monitoring of the fluid was carried out during two periods of differing exploitation conditions, respectively pumping at 148 m{sup 3}/h and artesian flow at 36 m{sup 3}/h. Vertical heterogeneities of the aquifer can explain the variations observed for the high flowrate. Filtration experiments revealed that the particle load varies with the discharge rate and that over 95 weight % of the particles are smaller than 1 micrometer. The chemistry of the particles varies greatly, according to their origin as corrosion products from the well casing, particles drawn out of the rock or minerals newly formed through water-rock reactions. Finally, small-scale oxidation experiments were carried out on the geothermal fluid to observe the behavior of Fe and SiO{sub 2} and to favour particle aggregates for easier filtration or decantation processes.
- Research Organization:
- Institut Mixte de Recherches Geothermiques, Orleans Cedex, FR
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AS07-84ID12529
- OSTI ID:
- 887299
- Report Number(s):
- SGP-TR-113-44
- Resource Relation:
- Conference: Proceedings, thirteenth workshop on geothermal reservoir engineering, Stanford University, Stanford, CA, January 19-21, 1988
- Country of Publication:
- United States
- Language:
- English
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Chemical study of a low temperature geothermal fluid in a triassic sandstone aquifer; Scaling potential and fluid treatment (Melleray, France)
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