Compositional Kinetics of The Bazhenov Kerogen Thermal Destruction: The Effect of Organic Matter Maturity

Abstract

Summary The work is devoted to the experimental study of the compositional kinetics of kerogen thermal transformation to petroleum for 5 samples from the Bazhenov formation (West Siberia Petroleum Basin). Rock samples containing kerogen of different maturity show gradual change of the bulk kinetic spectra shape from nearly symmetric for immature kerogen to asymmetrical for overmature kerogen (constant frequency factor А = 1×1014 s-1 have been used). For compositional spectra calculation, total HC yield was divided to 4 pseudo-components: gas С1-C5, С6, oil С7-С15 and heavy hydrocarbons С16+, derived from results of pyro-GC-TOFMS/FID analyses. For immature sample, percentage of gas in kerogen decomposition products is 35%, parts of С6, С7-С15, C16+ are 7, 42 and 16 %, respectively. Considering samples from immature to overmature, we noticed a decrease of gas and C16+ percent in the products, along with increasing C6. The main products are oil hydrocarbons С7-С15, the maximum in oil window is 49%. The obtained compositional kinetic spectra are used in petroleum system modeling of hydrocarbons generation during geological history. The results could be applied for the simulation of organic matter transformation into oil and gas in the technological process of thermal EOR (steam, supercritical water, high pressure air injection).