Composition and Distribution of Microelements in Rocks, Extracts, and Asphaltenes from Domanik Deposits of Various Lithologo-Facial Types of Romashkino Oilfield

Abstract

Abstract: Comparative studies were made of the microelement composition of rock samplesfrom Domanik deposits of different lithologo-facial types: from Semiluki–Mendym(Domanik) deposits of the Berezovskaya area and from carbonate domanikoiddeposits of the Dankovo–Lebedyan horizon of the Zelenogorskaya area of theRomashkino oilfield. These samples differ in the organic matter (OM) content andin the content and composition of petroleum hydrocarbons (HCs) and kerogen.Distinctive features of the composition and distribution of biogenic, rareearth, and radioactive microelements (MEs) in the initial rocks, rock extracts,and asphaltenes recovered from them were revealed. The Domanik carbonate–silicarock of the Berezovskaya area, in contrast to the carbonate rock of theZelenogorskaya area, is characterized by diversity and high concentrations ofall the ME groups with the highest content of V, Ti, Fe, Zn, Ni, Cu, Cr, Ba, Mo,and Mn. In the carbonate rock from domanikoid deposits of the Zelenogorskayaarea, the concentration of these MEs is considerably lower, as well as theconcentrations of rare earth and radioactive elements; the group of highlyvolatile chalcophilic MEs including Ge, Ga, As, Se, Cd, Sb, Te, Re, Hg, Tl, andBi is virtually absent. Both types of rocks contain Sr. In the extracts andasphaltenes, V, Ni, Fe, and Zn are the most abundant MEs. The highestconcentrations of V, Ni, and Zn were detected in carbenes and carboids of theBerezovskaya area. The ME composition suggests different conditions of the OMtransformation and ME accumulation in rocks from Domanik deposits of differentlithologo-facial types due to different intensity of the development of tectonicprocesses and supply of deep hydrothermal fluids into the deposit strata on theexamined territory of the Romashkino oilfield.