Objective
Demonstration of the possibility of utilizing the fluid of Latera (high temperature and medium salinity) for electrical purposes, with an increase of the share of electric power produced with alternative sources.
It is planned:
- to install a back pressure turbine of 4,5 Mw capacity supply in vapour by the well L3D
- to test a plant for scaling inhibitor injection to prevent or at least reduce the scaling phenomenon
- to get the remaining water into the well L2 by means of a pipeline between L2 and L3D.
Obtaining useful information (both with regard to plants and corrosion and concerning the chemism of the fluid for the scaling aspect) for subsequent design and realization of a double flash geothermal power plant to be built in the Latera area.
Energy savings expected are 6,500 TOE/year with a corresponding payback of 5 years.
The wells L2, L3D, L4, L10 and L11 have proved to be productive, producing a two-phase mixture of water, steam and gas with an enthalpy of about 0.9 - 1 MJ/Kg (L2, L3D, L4), steam and gas (L10) or mainly CO2 (L11). Well L3, however, was non-commercial; wells L14, L14 bis, Valentano 2 and Gradoli 2 are reinjection wells and the remaining wells L1, L5 and L6 are sterile.
During the production tests, scaling phenomena were noted on the inside of the wells, in the pipes, and in the atmospheric separators (mainly CaCO3 scaling; silica scaling should not be a serious problem, unless the brine temperature falls well below 100 deg. C.).
To solve the carbonate scaling problem, experimentation was carried out successfully on the injection of scaling inhibitor at wellhead, and will be performed downhole; as a precautionary measure against silica scaling, reinjection under pressure at high temperature was tested, with a positive outcome.
The results obtained so far with the experimental single-flash geothermal power plant have been quite good; net energy output was about 10 million KWh in the first year of operation. A payback period of 4 years is envisaged for the investment outlays for the production (4.5 MW) and reinjection plants, with an energy saving of 6,500 TOE/year.
The reinjection of waste water, after an initial period, was shifted over to well L14 bis, in order to regain L2 as a production well.
The modifications for supplying the power plant not only from well L3D but also L2 are now being made in order to permit long production testing of the latter well.
In the light of the encouraging results obtained so far, a 15 MW double-flash power plant will be installed in the near future, parallel to the drilling of new field development wells.
The possible installation of a second power plant will be assessed after a sufficient period of operation; should the decision be affirmative, a total capacity of 45-50 MW could be installed in the medium term.
It shouldbe mentioned that following completion of the first unit, a considerable quantity of water at about 120 deg.C. will be available (1000 - 1200 t/h), with a potential energy saving of 80,000 TOE/year, after its use for electricity generation. Utilization of this residual heat for district heating will therefore be studied. Further electricity generation could also be achieved with binary cycle energy converters with R 114 as intermediate fluid, utilizing the residual water coming from the second flash, upstream from the thermal utilization.
In the geothermal research area named "Latera" (Northern Latium), in an ENEL-AGIP joint venture, a geothermal reservoir of the water dominated type with high enthalpy and medium salinity was found. On the basis of the studies and the geological, geophysical and geochemical surveys carried out, a number of wells were drilled in the Latera geothermal area, 9 of which are productive, among them Latera 3D and Latera 2. As a result of the production tests conducted on these wells and the outcome of the exploratory drillings performed in the zone, it was decided to build a demonstration plant for the production of electric energy by means of a flash vapor cycle, to be sited in proximity to well Latera 3D.
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
00198 ROMA
Italy