Taking into account the world-wide energy crisis, the search and rational use of cheap
andecologically pollution-free renewable energy sources are extremely important. Among
these sources the geothermal energy is of great potentialities. Tbilisi has a high
potential of geothermal sources, which have been in use since ancient times. The major
areas of utilization are balneology and local heating of community and residential
buildings. It also should be noted that most of the geothermal wells are non-operational.
Therefore, a re-assessment of the geothermal potential of the Tbilisi deposit is of
major importance from the standpoint of economic development based upon renewable,
ecological cleaner energy sources. Field hydrogeophysical investigations (tentative
testing, regime hydrodynamic and hydrochemical observations) have been carried out
to assess the main thermo-hydrodynamic parameters of water containing horizons. In
the field and laboratory conditions thermal properties of aquifer matrix rocks as
well as vertical and horizontal zonality of thermal flow have been investigated.During
testing the hydrodynamic influence of well Lisi 5 on wells Lisi 7 and 8, as well as
on well Saburtalo 1 was established. It appears that wells Saburtalo 4 and 6 are out
of influence area, they are not influenced by well Lisi 5, which points to their independent
regime. For the proper characterization of this water regime and assessing its influence
area additional testing should be carried out in the future.Based on previous and
newly obtained geologic, hydrogeological and geophysical data, 3D model of Tbilisi
thermal region was created which takes into account complexity of area, its separation
into domains by faults, and their different hydrodynamic zonality. For modeling computer
softwares such as Feflow 5.3, AquiferTestPro, etc. have been applied, which enabled
to define hydrothermal resources and assess hydraulic parameters of water containing
layers. As a result of modeling work, the 10-year perspective of thermal deposit
of Tbilisi was assessed at the present conditions of exploitation.In the whole region
subsidence of water horizon is expected. For example, in the Lisi district, if mean
yearly discharge (exploitation rate) is preserved, water table drops by 2-5 m and
the released thermal energy decreases from 5.5*1020 to 1.578*1017
J. According to the simulated geothermal circulation system, when the used water
of well 5 (1690 m3/day cooled down to 30 0C) was reinjected
to the well 1 with negative level, ‘cooling of horizon and subsidence’ tendency became
slower. Therefore, in the future creation and implementation of geothermal circulation
systems are recommended. This will help to achieve economical and ecologically approved
exploitation of geothermal resources.
