| Title | Innovative Reservoir Management in Superheated Steam Geothermal System: Micro-reinjection and Push&pull Production |
|---|---|
| Authors | Maurizio CEI, Sara MONTOMOLI, Fabio SARTORI |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Larderello, Valle Secolo, reinjection, micro-reinjection, push-pull, reservoir management |
| Abstract | The Larderello geothermal system is one of the few geothermal systems in the world characterized by a reservoir dominated by superheated steam. The long exploitation history of Larderello, which has been in operation for over 100 years, has led to a general reduction in reservoir pressure, contributing to increase the overheating of geothermal fluid, particularly in the historical area of Valle Secolo. Thanks to these favorable thermodynamic conditions, reinjection has been a fundamental tool for the resource management in Valle Secolo area for over 30 years. In fact, water injection into the geothermal system partially compensates steam extraction and helps to reduce the reservoir pressure decline. The stabilization of electricity production and reduction in pressure decline in Valle Secolo is a check of the effectiveness of reinjection strategy. High and uniformly distributed permeability is necessary to obtain a significant return in terms of secondary vapor produced by the injected water and to avoid break-through between injection and production. Unfortunately, not all the areas in exploitation in Larderello match this requirement. In the last few years, Enel Green Power has tested and implemented innovative reinjection methods that allow energy extraction where favorable thermodynamic conditions exist in the reservoir, even where an appropriate homogeneous permeability is absent. In particular, in this paper the Micro-reinjection technique and the Push&Pull strategy are described in details. Micro-reinjection is based on direct break-through between the reinjection and production wells, while the Push&Pull strategy uses existing unproductive or low steam productive wells that are characterized by high reservoir temperatures. Overall micro-reinjection and Push & Pull applications allow increasing about 10 MW until today. |