The conceptual model was converted to a numerical model for simulating the regional fluid and energy balance; identify areas for exploitation; and evaluate alternative exploitation scenarios. The Tbilisi deposit simulation was carried out over a 10 year period assuming current exploitation conditions. Results indicate that future water pressures will decrease at all wells resulting in subsidence (Fig. 30.3). Balance calculations also show energy losses at the thermal field boundaries resulting in an overall negative balance for the deposit. Similar results were obtained for wells in the "Lisi" district. A second "Lisi" district scenario evaluated the exploitation with reinjection into the deposit. This involved the simulated reinjection of hot water using wells 1 and well 5 over a 10 year period. Results indicated that the "Lisi" well pressure decreases were moderate (compared to the Tblisi deposit) with increases of water temperature in well 5 (Figs. 30.4 and 30.5). As a consequence, the total thermal balance for the "Lisi" district, where reinjection was simulated, became positive (Fig. 30.6) [3].

J Precipitation GUZD Lower Eocene aquifer H-r^-l-l Middle Eocene aquifer Aquitard

Heat flux


Samgori oil field

Lisi hydrothermal field Central Tbilisi hydrothermal field Mtkvari river

325 m

Constant-head boundary

Fig. 30.3 Block diagram of conceptual model

Fig. 30.4 Variation of pressures for 10 year
Fig. 30.6 Thermal balance for reinjection during 10 years
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