Study on the Potential of Shallow Geothermic Reservoirs in Milos Island

Industry: Renewable Energy Sources

Location: Greece

Duration: 3 years (2002 – 2004)

Amethyst SIEE in association with Energy Mining Enviro Ltd. , GSDP, Center for Renewable Energy Resources, Aristotelian University of Thessaloniki, Datamine Intl, and GeoScience Ltd. carried out a study on the potential of shallow geothermic reservoirs in the Island of Milos. The project was undertaken and completed in multiple phases:

• All relevant historical and geological data concerning the Milos Island were gathered, thoroughly studied and evaluated, with the primary aim of information filtering and the consequential production of the database “tools” that would assist us in the following steps.
• Following the initial stages of data-mining the development of a GIS-based and oriented architecture for hosting the aforementioned database “tools” was initiated. A great number of high definition data were imported into the database so as to be used either in the field or as the primary Knowledge Base for the digital geothermal model. The imported data include:

• The topography of the entire island of Milos in 2 categories: one crude 40-m contour map and one delineated 4-m contour map of high resolution with separate focus-terrain libraries. This data was thoroughly digitized and converted into a Digital Terrain Model – a three dimensional representation of the island’s surface.
• The geology of the entire island in the form of a complete, electronic format, interactive geological map with the full tectonic characters, etc. / including a library with digital cross-sections covering the focus areas
• The temperature profile of the entire island subsurface in the form of a potential contour map of the geothermal gradient (including the actual well loggings at about 60 sites with temperature readings every 10 m along with historical data of the old production wells – in total over 500 temperature reading values)
• The geochemistry and all related characteristics of the entire island based on fluid and gas analyses at approximately 100 sites
• The geophysics and related methods results for the entire island (resistivity/iso-potential, gravimetrics, geo-electrical, seismic, magnetotellurics, etc.
• The production wells of all  historical fields including coordinates, lithology, drilling and casing technical characteristics, general info during well development and production, full loggings data, chemical analyses results, geothermal characters and production well data such as pressure, temperature, enthalpy, emissions, etc.
• New production wells – focus field, including coordinates, lithology, drilling and casing technical characteristics, general info during well development and production, full loggings data, chemical analyses results, production well data (as in the above). In total 5-8 wells (1-3 exploration, 2-3 production, 2 re-injection) were realized and 1200 m to be drilled, over 1000 values of recorded data
• All relative documentation was also provided (where available in English) that included the Thesis on the modeling of the «Zefyria-Agrilies» geothermal field (adjacent site) that had already undergone exploration and pilot exploitation.

 

• Using the above data a desk study was conducted to estimate the extent and characteristics of the geothermal reservoir.  The study was focused primarily on the upcoming phase of drilling, however the historical data in the Knowledge Base was used to confirm/reject validity of assumptions and modeled parameters (by GeoScience Ltd in cooperation with Datamine and Amethyst).  The Geothermal parameters that were estimated included a) Permeability, b) Pressure, c) Water flow rate, d) Water/Steam Phase ratio, e) Fluid Salinity and Acidity, f) Temperature, g) Specific Enthalpy of Fluids and h) Resistivity among others

The general scope of the desk study was:

• To utilize all existing info & relative data from geological, geophysical, geochemistry and bore hole (exploration & production) investigations, available from studies in the greater region of Milos.
• To derive information from exploration and production drillholes conducted during this project, which would later be incorporated in the general plan of the area and compared with existing data.   
• To estimate the geothermal reservoir in the field of interest, taking into account the requirements of the project.

 

• The Reservoir potential was assessed, in order to ascertain the suitability and capacity of the geothermal field for power generation, as this is the primary objective of the project. Secondarily, low enthalpy applications (heating) from this resource were also researched.

Finally, the results of the reservoir modeling desk study in turn were converted in a suitable format and included into the Knowledge Base.  The presentation of the final results was made in portable 3D viewable format, in addition to a written report. 
The client received a user-interactive database of fixed results which allowed certain sensitivities of reservoir potential to be assessed.

Following the completion of the preliminary study, Energy Mining Enviro Ltd. was assigned the task of realizing the project. Alexandros Papakostas, who at the time was also vice-chairman of MILOS S.A., undertook the complete licensing of all technical aspects (drilling, monitoring etc.), as well as the environmental licensing and monitoring that was required by the Greek legislation and authorities. This involved the close examination of all the technical and environmental parameters of the proposed project, such as:

• The probing of the area, to assure the existence of liquids of adequate volume and temperature.
• The definition of the physical and chemical characteristics of the geothermal fluids, which would be of outmost importance for the success of the project
• The efficient recycling of all liquids after their use, which included their redirection into the geothermal reservoir.
•  To assure the protection of both the natural environment and the natural resources of the island.

 

Fragou Law Firm was entirely responsible at the time for preparing all necessary legal documents for the lease of the project’s area, while also providing legal counsel and acting as a mediator between the contractor, the local officials and the Ministries of Development and Environment.