A Reservoir Engineering Study in Gabbro Zone (Northern Part of Larderello Field)
Gabbro zone, located north of the old geothermal field of Larderello, was explored after 1960 by several wells. The geology of this area is briefly described. Only a few wells were productive. The extension of research showed that the high productivity zone is surrounded by dry or low productivity wells (Fig. 1). Therefore it can be said that the wells inside the circle in Fig. 1 are producing from a reservoir closed in on every side except that of the old Larderello area. In particular, 90% of production is concentrated in an area smaller than 1 km{sup 2}. The non-commercial wells have been shut-in since they were first drilled. The producing wells deliver superheated steam at a well-head pressure between 5 and 8 ata (kg/cm{sup 2}a) and at a temperature of 230º C. This work sets out to analyze shut-in pressure and flow-rate declines. The hypothesis of a closed gas reservoir, as assumed in the analysis, does not seem to work in our case, especially in view of the fact that an unknown amount of fluid is flowing from this area toward the old Larderello zone. Some sort of water recharge, a feeding from deep subvertical fractures, or the initial presence of liquid and steam simultaneously in the reservoir, must be admitted. 8 figs.
- Research Organization:
- C.N.R., Istituto Internazionale per le Ricerche Geotermiche, Pisa Italy; ENEL, Centro Ricerca Geotermica, Pisa, Italy; ENEL, Gruppo Minerario Larderello, Larderello, Italy
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 887385
- Report Number(s):
- SGP-TR-20-21
- Country of Publication:
- United States
- Language:
- English
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