Communication Microcomponents Underground Waters of the West Siberian Megabasin with the Staging of Oil Formation

Analysis of the conditions of migration of microcomponents in the underground waters at different lithogenesis stages shows that the redistribution of substance becomes most active starting at the later stages of diagenesis and the early stages of catagenesis (after N.B. Vassoevich). The main oil forming stage thus appears from the point of view of underground water geochemistry as a period of maximum enrichment of the waters in trace elements and organic matter.

Microcomponents of underground waters are very clear indicators of the processes in the oil formation. The set-in of the main stage is marked by a distinct jump in microcomponents concentration, which in West Siberia occurs at depths of 1500-2000 m.

A more detailed study of microcomponents distribution in waters, taking account of the temperature regimes in the various areas of the West Siberian basin, shows a differentiation in the depth of the concentration jump (in the Urals province, 1000-1500 m; in the Nizhnevartovsky province, 1500-2000 m; and in the Surgut province, 2000-2500 m). By the absence of decaying branches in the graph formation of oil we have predicted "big oil" in the north of Western Siberia.

The attenuating stage in the microcomponents concentration pattern differs less sharply from the main one than the preliminary stage does, although the drop in the content is clear in the Urals province at depths of more than 2000 m, and in the Surgut and Nizhnevartovsky, beneath 2500 m. Regional factors of the evolution of the geochemical picture of underground waters are intrinsically linked with lithogenesis and the stage in oil formation. This allows underground water geochemistry data to be used in solving theoretical problems of oil and gas geology and in making regional forecasts of oil gas prospects.