Problems of migration of Polish crude oils on the basis of geochemical correlation data and carbon isotope composition

Abstract

A method for the correlation of crude oils has been worked out on the basis of analyses of 120 crude oils from 4 geological regions of Poland. The first stage of the correlation consists in selection of crude oils into groups or families on the basis of structural and group composition of the hydrocarbon part of the crude oil, i.e., on its Y and X values. The family consists of crude oils which undergo the same chemical metamorphism and derive from the same source material. The second stage of the correlation refers to a differentiation of crude oils, within the family, according to their degree of metamorphism. In the third stage, probability calculus has been applied with the aim of distinguishing crude oils of about the same age (generations of crude oils). The results of the correlation made in 4 regions are presented, as is also the carbon isotope composition of 35 crude oils. Geochemical and geological data have been compared and conclusions have been drawn from these. Carboniferous sediments have been estimated as source rocks for crude oils from the Carpathian flysch and the Carpathian foreland. Formation of the older generation ( A) of crudes began in the Early Cretaceous; that of the younger generation ( B) in the older Pliocene. Silurian sediments have been estimated as source rocks for crude oils from the synclinorium of Lublin. Formation of the crudes began in the Late Carboniferous. The Hauptdolomite of the Zechstein is regarded as a source rock for crude oils from the Sudetic foreland monocline. Formation of these crudes began in the Jurassic, and migration and accumulation occurred within the source rocks. Migration channels in each region are discussed and perspective areas for crude oil exploration are proposed.