Domanik Deposits Research Articles

Effect of Hydrothermal Treatment and Prolonged Extraction on the Generation of Hydrocarbons from High-Carbon Low-Permeability Rocks from Domanik Deposits

Effect of Hydrothermal Treatment and Prolonged Extraction on the Generation of Hydrocarbons from High-Carbon Low-Permeability Rocks from Domanik Deposits

Geochemical properties of the upper devonian deposits (Semiluk, Mendym and Kynovian horizons) of the Volga-Ural province for improving the Romashkinskoye oil field development efficiency

This paper presents the results of geochemical and petrophysical studies of the Semiluk-Mendym (Domanik) and Kynovian deposits of the Frasnian age of the Devonian system at the Romashkinskoye giant oil field of the Republic of Tatarstan. The biomarker composition of the organic matter of the rocks is shown, its catagenetic maturity and facies conditions of its formation are assessed. In addition, the composition of saturated biomarkers (alkanes, steranes, and triterpanes) of Devonian oils were studied. The correlation «oil-organic matter of rocks» was carried out for oils of the Domanik and Kynovian horizons. It is shown that the differences in the biomarker composition of oils from the Domanik and Kynovian horizons are of practical importance in the field development process, since this allows optimizing the oil production process by evaluating the contributions of oil inflows from different reservoirs. Keywords: Domanik deposits; oil geochemical research; biomarkers; alkanes; terpanes.

Geochemistry of hydrocarbons-biomarkers and carbon isotopes of organic matter in the Domanik Deposits of the Timan-Pechora Basin

It has been established that the average values of some hydrocarbons biomarker coefficients of bitumens from the Domanik deposits and oils from the Domanik–Tournaisian complex coincide. These are the proportions of C27–C29 steranes, tri-/pentacyclanes ratio, and coefficients 2 × С17/С16 + С18 and 2 × С27/С26 + С28 calculated from n-alkane composition. Such indicators as the Pr/Ph, (Pr + Ph)/(n‑C17 + n‑C18), dia-/reg-steranes, and the sterane/hopane ratios in oils are slightly lower than in the bitumen. The average values of δ13C in asphaltene, resin, aromatic hydrocarbons, and aliphatic hydrocarbons fractions from oils of the Domanik genotype and in the studied bitumens are similar. The carbon isotope composition of asphaltenes in oils is depleted in 13С compared to those of resins and aromatic hydrocarbons, and vice versa in bitumens. A heterogeneous composition of the bacterial flora in the sediments of the Domanik Sea is suggested. In some places, species with high concentrations of diplopterol or hexafunctional bacteriohopanes likely dominated over bacteriohopantetrol.

Geochemistry of Hydrocarbons-Biomarkers and Carbon Isotopes of Organic Matter in the Domanik Deposits of the Timan–Pechora Basin

Geochemistry of Hydrocarbons-Biomarkers and Carbon Isotopes of Organic Matter in the Domanik Deposits of the Timan–Pechora Basin

Influence of Supercritical Water on the Composition and Distribution of Microelements in Resins, Asphaltenes, Kerogens, and Rocks of Tatarstan Domanik Deposits of Different Lithological Types

A comparative study of changes in the microelemental composition and distribution in resins, asphaltenes, and kerogens from Tatarstan Domanik rocks, occurring under the action of supercritical water (SCW) at 374°С and a pressure of 22–24 MPa, was made. The samples studied belong to different lithological types; they were taken from carbonate–siliceous deposits of the Romashkino and Tavel oilfields and from carbonate deposits of the Bavly oilfield. The specific features of distribution of different microelements (MEs) in rocks and rock organic matter (OM) components were revealed by inductively coupled plasma mass spectrometry (ICP-MS). The major MEs are Fe > Ti > Ni > Zn > V > Cr > Cu with the concentrations from 100 to 8600 ppm. The total ME content of rocks from these deposits is 1.14, 0.23, and 0.38%, respectively. The ME content of resins and asphaltenes does not exceed 0.3 and 2%, respectively. The highest ME content, 8%, is observed in kerogens. The carbonate–siliceous rocks from different deposits with Сorg 7.07 and 1.90% differ from the carbonate rock with low Сorg (0.33%) in that the ME concentration in them is maximal. On the other hand, the ME content of resins and asphaltenes from the carbonate rocks is higher compared to the carbonate–siliceous rock samples. The concentrations of Fe, Cu, As, Se, Pb, and Bi in kerogens of all the types decrease under the action of SCW. In the transformed resins and asphaltenes from carbonate–siliceous rocks, the V and Ni concentrations appreciably decrease, whereas in kerogens their concentrations do not change noticeably. The demetalation processes lead to the ME redistribution between the OM components and mineral surface of the rocks.

Petrophysical modeling of rocks dominik formation as the basis of interpretation of seismic data

The paper is devoted to theoretical modeling of effective elastic properties of rock samples of domanik deposits. To determine the effective elastic properties of rocks, depending on their composition and morphological characteristics, the methods of effective medium theory were used. The aim of the work was to determine the parameters characterizing the microstructure of the investigated rock samples; creation of a seismic-geological model and calculation of reflection coefficients for it. The main attention in the work is paid to the influence of the content of kerogen and the degree of its maturity (porosity) on the measured physical quantities (velocities of elastic waves, reflection coefficients).

Features of the trace element composition of carbonaceous formations

On the example of carbon-bearing formations, the concentration of a complex of trace elements in them is estimated. Examples are given of the distribution of productive continuous reservoirs in the Ordos (China), AustinChok, Bakken (USA) basins, as well as in the Domanik deposits of the Volga-Ural oil and gas basin. The features of the formations, namely the large length of the productive intervals of the section introduced into development during horizontal drilling, as well as the high concentration of ore metals and other environmentally hazardous chemical elements both in the shale deposits themselves and in shale oil, require a new approach to the study of shale deposits in all stages of geological exploration.

Geological structure and oil and gas potential of Domanik deposits in the central part of the Volga-Ural oil and gas basin

The paper describes the structure and depositional conditions of a domanicoid high-carbon formation (HCF) in the central part of the Volga-Ural oil and gas basin. The structure of the HCF depends on the structural relatedness and paleogeographic conditions of the Late Devonian period, where the time of maximum sea level standing within the basin led to deposition of high organic carbon content intervals. The structural-facies zonation of the HCF distribution area is associated with the zone of relatively deep-water depressions, the zone of slopes, highs and the shallow water shelf with numerous bioherm buildups. The boundaries of the zones were determined by the position of large structural elements of the Tatar and Bashkir arches and depressions of the Kama-Kinel system of troughs. These zones differ not only in the distribution of the thickness of HCF deposits, but also in the nature of the distribution of intervals of the section enriched in organic matter. The maximum number of interlayers enriched by organic matter of the siliceous-carbonate rocks is observed in the section of the Frasnian and Famennian deposits within the central part of the Kama-Kinel system of troughs. Numerous of oil shows from the HCF intervals indicate the potential for further study and spotting of promising areas for hard-to-recover hydrocarbon reserves exploration.

Геохимия органического вещества аноксических бассейнов

The paleo-anoxic events influence on the accumulation of organic matter in carbonaceous marine sediments is considered. Aryl carotenoids derivatives found in bitumoids of the Upper Jurassic oil shales of the Russian Plate, Domanik deposits of the Pechora Basin, and other sequences indicate the photic zone anoxia of paleobasin waters. Dissolved hydrogen sulfide interacts with lipids and carbohydrates of the original organic matter and forms a wide range of soluble and high-molecular sulfur compounds. The analysis of the pyrolysis products composition of Jurassic oil shale sulfur-rich kerogen indicates a significant proportion of sulfur bound sugars in structure, as well as the formation of polysulfur bound n-alkyl fragments. The Domanik deposits kerogen structure is rich in sulfur bound n-alkyl fragments, producing a lot of n-alkylthiophenes and benzothiophenes under pyrolysis.

Hydrocarbon Composition of Products Formed by Transformation of the Organic Matter of Rocks from Tatarstan Domanik Deposits in Supercritical Water

Hydrocarbon Composition of Products Formed by Transformation of the Organic Matter of Rocks from Tatarstan Domanik Deposits in Supercritical Water

On the classification diversity of oil and gas trappers and geochemical criteria for the productivity of shale formations

The article considers the classification attributes of non-anticlinal traps on the basis of analytical research and critical analysis of literary sources. A certain excess of classification definitions and characteristics of traps, used by researchers both to describe universal schemes and for specific oil and gas basins, and their frequent discrepancies reasonably lead ultimately to an enlargement of types and subtypes of traps, combining them into three main classes of accumulations: continuous and quasi-continuous (unconventional) and discontinuous (conventional). It is noted that in combination with geophysical, seismostratigraphic, paleogeographic, paleotectonic, hydrogeological and other methods of studying the genesis and morphology of traps, and their search, geochemical methods of forecasting and searching for hydrocarbon accumulations at all stages of prospecting and exploration are now widely introduced. The practical possibilities of geochemical methods for evaluating the effective productivity of thin traps of carbonaceous formations are shown on the example of the Bazhenov and Domanik deposits of Russia, as well as the shale plays of the Bakken, Eagle and others in the United States. Keywords: non-anticlinal traps; thin traps; reservoirs; oil and gas; classification of traps; carbonaceous formations; geochemical studies.

Organic Matter of Domanik Deposits of the Timan–Pechora Basin: the Oil Window Conditions

Abstract —A comprehensive study of Domanik deposits of the Timan–Pechora Basin has been carried out. The examined composition of hydrocarbon biomarkers, chemical structure of kerogen, carbon isotope composition, and rock lithology, the Rock-Eval pyrolysis data, and the contents of bitumen and Corg in the rocks give an insight into the geochemical processes in the oil window in the Domanik deposits, which took place at Tmax = 435–450 °C. The bitumen coefficient βCB is maximum in this temperature interval, reaching 30%. The obtained data on the distribution of polycyclic biomarkers in the Domanik rocks and the bitumen and Rock-Eval pyrolysis data allowed determining the boundary values of biomarker maturity coefficients in the study of the maturation of organic matter of the rocks. The carbon isotope composition of bitumen fractions in the Domanik rocks is considered, and the bimodal distribution of the δ13C values of the bitumen is shown.

Structure and Assessment of the Oil Potential of Carbonaceous Carbonate-Siliceous Domanik Deposits in the Volga–Ural Oil and Gas Province

Abstract —The paper considers the regularities in the structure and conditions of formation of Domanik carbonaceous carbonate-siliceous productive deposits. They are shown to occur in the stratigraphic interval from middle Frasnian to upper Famennian. The highly persistent structure of their sections for many kilometers within specific sedimentation zones and the drastic changes in the structure at the boundaries of the zones are justified. Lithological classification of rocks is considered. Methods and results of combined paleontological, lithological, geochemical, and petrophysical core studies are presented, as well as interpretation of well logging data and seismic-survey materials used in the assessment of oil resources and identification of oil- and gas-promising zones and areas. The conducted studies have proved significant oil resources in the Domanik productive sequence; their extraction might compensate for the decline in oil production from conventional pools.

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

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

A New Indicator of the Maturity of Organic Matter from Domanik Deposits

Abstract —Study of the aromatic fraction of Late Devonian oils and organic matter from domanik deposits of the Timan–Pechora petroleum province has revealed compounds whose proportion depends on the degree of OM transformation, namely, 1,1,7,8-tetramethyl-1,2,3,4-tetrahydrophenanthrene (1,1,7,8-TMHP) and 1,2,8-trimethylphenanthrene (1,2,8-TMP). It has been established that 1,1,7,8-TMHP dominates over 1,2,8-TMP in the immature OM; as the thermal maturation of OM increases, 1,2,8-TMP begins to prevail. The same pattern is observed for the Late Devonian oils. An increase in the ratio of 1,2,8-TMP to 1,1,7,8-TMHP with the growing thermal maturation of OM and the transition of one compound into another permit using this ratio as an additional indicator of OM maturity in domanik rocks.

Fundamentals of well logging data interpretation for determining prospective Frasnian-Famennian Domanik deposits

Background. In the process of studying productive Domanik deposits of the Frasnian-Famennian, numerous uncertainties arise in identifying their effective thickness. Although several approaches have been recently proposed for identifying promising intervals in Domanik sediments, e.g. determination of the effective thickness using gas logging during geological and technical studies, the use of the interpretation method presented in the article and other methods continue to develop. Therefore, studies aimed at increasing their efficiency remain to be relevant.Aim. To develop basic methodological approaches to interpretation of well logging data with the purpose of identifying promising Domanik deposits rich in mobile hydrocarbons.Materials and methods. Geological and geophysical data obtained when investigating the wells of the according to published data of geological and geophysical resources of drilled wells in the Buzuluk depression were used to build the main well logging dependencies. In addition, the materials of core and geophysical studies of wells in the Volga-Ural oil and gas basin conducted by Gazprom Neft (PJSC) were used. Extended well logging data were collected for the wells under consideration. A number of tests and core studies, including geochemical experiments, which were carried out in deposits of Fran age, the density of resources of 5—10 samples per 1 meter of core.Results. For the first time, basic methodological approaches for identifying effective oil-saturated strata in Domanik sediments according to well logging data were developed. The developed approaches are based on the integration of geological-geophysical and geochemical data characterizing the material and mineralogical composition of rocks, the content of organic matter, the group composition of hydrocarbons and the genesis of reservoirs. In the section under study, rocks saturated with hydrocarbons were identified. The hydrocarbons were different in terms of group composition, which determined their mobility. Boundary values were obtained when interpreting data obtained by well logging methods for Domanik rocks containing mobile and stationary hydrocarbons. The proposed methodological approaches were tested on other wells in the Domanik deposits in the Orenburg region. As a result of repeated practical application and testing of the developed methodology, its effectiveness was confirmed.Conclusions. The proposed basic methodological approaches for interpretation of well logging data when identifying effective oil-saturated strata were substantiated by the geological-geophysical and geochemical properties of Domanik deposits.

Comparative Analysis of the Composition of Carbon-Rich Rocks from Domanik Deposits and the Oil–Water Contact Zone Exemplified by Tatarstan’s Bavly Oilfield

Samples of carbon-rich rocks from domanik deposits and the oil–water contact zone of the Bavly field of the Republic of Tatarstan (Russia), as well as extracts from them, have been studied by thermal analysis, IR and EPR spectroscopy, and gas–liquid chromatography. Significant differences have been revealed in the chemical composition and physicochemical properties of both soluble and insoluble organic matter from various areas of the Bavly field. Compared with bitumens from the oil–water contact zone, bitumoids from domanik deposits are heavier; they are enriched in oxidized structures and contain elevated levels of isoprenoid hydrocarbons and light normal alkanes. Bitumoid asphaltenes are enriched in sulfur and nitrogen, depleted in oxygen, and characterized by an increased concentration of paramagnetic centers. These differences have to be taken into account when testing technologies for the development of domanik deposits.

Comparative Analysis of Organic Matter of Reservoir Rocks and Domanik Deposits of the Bavly Oil Field

Core material taken over a section of the Bavly multipay field of Tatarstan (Russia), and extracts from it have been studied by thermal analysis, IR and EPR spectroscopy, and gas-liquid chromatography. The trends of changes in the amount and fractional and hydrocarbon-group compositions of residual oil and oil components irreversibly adsorbed on the rock depending on the age of deposition have been revealed. In rocks from the Trans-Volgian and Dankovian–Lebedyanian horizons attributed to domanik deposits, the organic matter content has been determined with an estimate of the proportion of bitumoid and kerogen in it, and the peculiarities of their fractional and hydrocarbon-group compositions have been revealed.

Ароматические биомаркеры стеранового и гопанового рядов в верхнедевонских нефтях и битумоидах доманиковых отложений Тимано-Печорского бассейна

Ароматические биомаркеры стеранового и гопанового рядов в верхнедевонских нефтях и битумоидах доманиковых отложений Тимано-Печорского бассейна

Electron Microscopic Study of Siliceous-Carbonate Rocks of the Domanikoid Type

The methods and results of electron microscopic study of the microstructure of siliceous-carbonate rocks of the domanikoid type are shown. For this purpose, both standard methods for studying the surface of sample chips and a polished surface for microprobe studies and a specially developed method for cathode luminescence study of the pore space are used. Regularities in the catagenetic transformation of Domanik deposits are studied at the microscopic level by electron microscopy. The performed studies show that subcapillary porosity in them is formed only in fractal-cluster areas of origin of secondary (authigenic and syngenetic) carbonatization. This study substantiates the fractal-cluster approach to the probabilistic forecasting of areas of secondary carbonatization and oil-saturated pore volumes.