This paper gives an overview of the current "state-of-the-art" in geochemical basin evaluation in the USSR.

First, I review the origin of oil and gas accumulations, as related to source-rock type and richness, the degree of maturation of the organic matter, and the changes occurring during migration. The dispersed organic matter in shale or carbonate formations is considered to be the source material for the oil and gas, migration taking place as a solution in formation water (aquabitumoids).

Next, I give a semi-quantitative approach to the calculation of hydrocarbon charge and accumulation efficiency in sedimentary basins, illustrated with examples from Siberian basins. The cornerstone of these methods is determining the bitumoid (extractable organic matter) content of the presumed source beds and its change due to progressing maturation and expulsion. Comparisons between calculated effective expulsion from the source formations and oil and gas field distributions indicate that the richer deposits are concentrated in those parts of the basins where most oil charge was expelled.

Finally, this paper includes a comprehensive list of mostly Soviet literature dealing with geochemical basin evaluation.