Utilization of thermal waters from oil deposits of the caucasus

Abstract

During the exploitation of many gas-oil fields of the Caucasus a great quantity of thermal water is obtained. This water, with great economical effect, is sometimes used for hot water supplying of industrial and agricultural enterprises and for heating different commercial services etc. Great prospects for a wide utilization of thermal waters are opened in connection with the developing of the oil deposits, namely of the productive horizons of the Middle Miocene deposits. From only one oil field (in the October district of the north Caucasus) 5.6–6.2 million m 3 of water is annually extracted together with the oil. During the whole period of development up to the 1st of January 1969, 260 million m 3 of water at the head of many wells is higher than 80 °C. The extraction of heat by water out of the interior of the oil field amounted to 15.8·10 12 cal for the 55 year period. For generating the same quantity of heat it would be necessary to burn 1.58 million tons of mazut, or 2.3 million tons of coal, or about 2.0 billion m 3 of natural gas. The development, over many years, of Middle Miocene deposits led to a considerable decrease of hydrodynamic levels and expansion of cones of depressions for scores of kilometers. As a result of this there followed the reduction of yield and even the exhausting of many thermal springs. Approximately 90% of the large total recovery of the aggregate amount of liquid from Middle Miocene deposits was from 3–4 levels. A sharp reduction in the recovery of liquid from levels and in connection with the considerable development of some deposits resulted in the increase of hydrodynamic levels. Water of the earlier productive horizons are now the source of thermal supplying of some industrial enterprises. Long regime observations of thermohydrodynamic parameters showed high reliability of hydrodynamic systems in the Neogene deposits. It was observed that while using thermal waters it is necessary to make up their reserves artificially. To determine allowable recovery of thermal water and, in connection with this, to determine the quantity of water injected into the stratum for the recovery of its resources, thermal calculations have been made according to the scheme including convection, transportation of heat in the stratum and heat transfer of the surrounding rocks in the vertical direction. The calculations showed that the most favourable conditions of work of the considered hydrodynamic system, the Black Mountains - Peredovoy ridges, can be created by recovery and injection of 100,000 or 50,000 m 3 water per day. The linear distance between the injected and exploited wells is 5000 meters. At the injection and the extraction of 25,000 m 3 water/day, the temperature of the level will not appreciably decrease. In the near future in the Caucasus, side by side with the direct utilization of thermal energy of the underground waters, the extraction from them of iodine, bromine and other elements can be organized. Thermal mineral waters can have a still wider use for balneology purposes.