Modeling of formation of petroleum biomarker hydrocarbons by thermolysis and thermocatalysis of bacterium biomass

Abstract

Thermolysis and thermocatalysis of the insoluble part of chemoorganoheterotrophic aerobic bacteria Arthrobacter sp. RV and Pseudomonas aeruginosa RM have been performed. The thermolyzates and thermocatalyzates of these bacteria contain the hydrocarbon biomarkers n-alkanes, isoprenanes, steranes, and terpanes. Of n-alkanes, the C9-C35 hydrocarbons with unimodal distribution formed in the products of or C9-C39n-alkanes with bimodal distribution are produced by thermolysis or thermocatalysis, respectively. n-Alkanes with odd number of carbon atoms in the molecule prevail over the even counterparts (n-C9, n-C11, n-C15, and n-C17) in the thermolysis products of both strains, whereas n-alkanes with even number of carbon atoms (n-C16, n-C18, and n-C20) dominate in the thermocatalyzates. Isoprenanes of the C13-C20 composition are generated. It is noteworthy that regular C17 isoprenane has been found for the first time among isoprenanes. The cyclic biomarker hydrocarbon steranes and terpanes are simultaneously generated, with the distribution of C27-C29 regular steranes resembles that in marine oils generated in argillaceous strata. At the same time, the adiantane to hopane ratio (H29/H30) is characteristic of the organic matter generated in carbonate strata.