Adamantane Hydrocarbons as Indicators of Oil Genesis in the Open System

Abstract

Hydrocarbons of the adamantane structure are referred to as hydrocarbon biomarkers. However, they differ from other biomarkers in that no analogues of hydrocarbons of adamantane structure in wildlife have been found. These hydrocarbons are assumed to have been formed because of structural rearrangements and at the polycyclic naphthenic hydrocarbons molecules fragmentation. Adamantane hydrocarbons, regardless of the deposit location, are featured by the pronounced nonequilibrium composition. This is, although in laboratory experiments at sufficiently low temperatures (180-220°C) equilibrium is reached within a few days. All these testify to the fact that the formation of adamantane structures has proceeded very fast, in the kinetic regime, and is most likely to associate with the processes of hydrocarbons migration into the deposit. Researchers of adamantane hydrocarbons indicate the option of adamantane structures formation in migration processes, though not specifying the mechanism of their development. It has been suggested that the formation of adamantane hydrocarbons proceeds dynamically in a stream of deep fluids in the supercritical state. The isomeric composition of alkyl adamantanes is determined by the time of contact with the rocks, as well as their catalytic activity. This can confirm the earlier assumption on oil genesis in thermodynamically open system.