Sub- and supercritical water in the processes of conversion of Domanik rock organic matter

Z.R Nasyrova,A.E Chemodanov,A.V Vakhin,G.P Kayukova,V.S Litvinenko

doi:10.1051/e3sconf/202126607001

Abstract

Studies on the conversion of organic matter of high-carbon Domanik (siliceous-clay carbonate) rock of the Romashkinskoye deposit with a mineral content Corg of 7.07% in sub- and supercritical water have been carried out. It was shown that subcritical water at a temperature of 320°С and 17.0 MPa leads to a partial decomposition of the kerogenic structure, increasing the yield of bitumen from 3.12 to 3.98%, and a more complete recovery of asphaltenes and heavy C22-C30 n-alkanes from the rock sample. Supercritical water at temperatures of 374 and 420°C and pressures above 24.4 MPa leads to intensive formation of hydrocarbon and inorganic gases in the processes of kerogen decomposition, destruction of aliphatic substituents from condensed heteroatomic structures of resins and asphaltenes, and the carbonate component of Domanik rock. Degradation of the organic matter of the Domanik rock is also accompanied by the formation of saturated hydrocarbons with an increased content of light C12-C21 n-alkanes, and carbonaceous substances, such as carbene-carboids. Changes in the structure of asphaltenes and their paramagnetic properties were determined by the EPR method. The influence of sub- and supercritical water on phase changes in the composition of rock minerals, as well as on the yield and composition of formed gases, was revealed.

Highlights

Shale strata in Russia are represented by accumulations of bituminous rocks of the Bazhenov Formation of Western Siberia and Domanik deposits of the Volga-Ural oil and gas province ΀ϭϮϯ΁
Studies on the organic matter (OM) conversion of the Romashkinskoye Domanikdeposit in sub- and supercritical water environment led to the following conclusions
Subcritical water at 320°C and 17.0 MPa leads to an increase in the yield of bitumen from 3.12 to 3.98% as a result of more complete extraction of asphaltenes and heavy C22C30 n-alkanes from the rock

Summary

Introduction

Shale strata in Russia are represented by accumulations of bituminous rocks of the Bazhenov Formation of Western Siberia and Domanik deposits of the Volga-Ural oil and gas province ΀ϭϮϯ΁. At high reservoir pressures and temperatures, methane, carbon dioxide, and water can become supercritical and exhibit increased chemical activity in the processes of OM conversion [5] It was shown in [10, 12, 13] that water under supercritical conditions at temperatures above 374.3°C and pressures above 22.1 MPa can penetrate the structure of kerogen and break its structural skeleton, leading to the formation of bituminous substances. This gives reason to believe that the development of Domanik sedimentary rocks can be carried out using supercritical fluids, in particular, supercritical water. This sphere is important and relevant from the point of view of studying the processes of oil formation and in terms of developing technologies for the development of Domanik strata

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