Important Factor of Variation of Physico-Chemical Properties of Oils.

The causes of variation of physico-chemical properties of oils of the Apsheron petroleum and gas-bearing region are, for the first time, considered from the point of view of thermal equilibrium of hydrocarbon systems, using the example of the deposits of the Kirmaku-Bakkhar anticlinal zone. The point is that a considerable change in the structural plane of the South Caspian depression basin in the Upper Pliocene-Quaternary period, caused by intensive bulging up of the edge zones and dipping of its central parts, has resulted in changes of the thermodynamic conditions of the strata systems. In the tectonic elements that rose highest, i. e. in the zones of intensive thermodynamic relief, the low-boiling hydrocarbons, possessing high vapor elasticity, owing to the impairment of the equilibrium of hydrocarbon systems, were separated from the oil and migrated upwards through the rock strata, where they saturated the upper intervals of the section. This mechanism fully explains the principal regularities in the geochemistry of petroleum in the Apsheron oil and gas-bearing region.