A Three-Year Recharge Test by Reinjection in the Central Area of Larderello Field: Analysis of Production Data

Abstract

Reinjection experiments have been carried out at Larderello in an attempt at limiting the strong decreases in pressure and production in the intensely exploited areas of the field. The first test, lasting about 3 years, was conducted in "superheated" zone of the reservoir, injecting at a rate of 10-50 kg/s into the upper productive parts of the reservoir. Despite the fact that the nearest well is only about 150 m away and more than 85% of the injected water was recovered, no breakthrough occurred, nor was there any decrease in wellhead temperature, in the neighboring wells. On the contrary, there was an increase in both production and conversion efficiency. The contribution of the injected water to production was evaluated by tracing techniques based on variations in the isotopic composition and in the noncondensable gas content of the fluid produced.