The Castelnuovo pilot concession is aimed at demonstrating the possibility of total reinjection of the geothermal fluid (brine and NCGs) in the same geothermal reservoir. According to Italian laws, these pilot plants must be limited to 5 MWe power output. The Castelnuovo-Mensano reservoir, however, is considerably large, so that the preliminary reservoir simulations have shown that it has the capacity of effectively retaining the reinjected gas flow rate, which – with careful management – should be confined into the permeable rock porosity or in local gas cavities, helping to maintain the original reservoir pressure.
The resource is expected to be saturated vapour at a pressure within the 60-80 bar range, 280°C temperature at about 3500 m depth. At well head, the expected resource conditions are 10.3 bars pressure and 180 °C temperature. The NCG mass content is estimated at about 8%, of which about 7.8% is CO2 and 0.2% H2S.
The project is waiting for the final approval from the Italian Ministry; according with the result achieved from the integrated modelling performed within the GECO project has been shown the feasibility of the total re-injection closed-loop system and the ORC binary power plant minimizing the visual impact on the landscape.
Figure 4 – Re-injection system
Figure 5 – Rendering of the planned geothermal power plant