Tag: porosity

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INFLUENCE OF THE PORE STRUCTURE OF FOSSIL ORGANIC MATTER ON METHANOGENESIS IN FREE-CHAIN RADICAL REACTIONS

Home > Archive > No. 2 (202) 2026 > 62–75

Geology & Geochemistry of Combustible Minerals No. 2 (202) 2026, 62–75

ISSN 0869-0774 (Print), ISSN 2786-8621 (Online)

https://doi.org/10.15407/ggcm2026.202.062

Myroslava YAKOVENKOa, Yurii KHOKHAb, Oleksandr LYUBCHAKc

Institute of Geology and Geochemistry of Combustible Minerals of the National Academy of Sciences of Ukraine, Lviv, Ukraine

a e-mail: myroslavakoshil@ukr.net, https://orcid.org/0000-0001-8967-0489
b e-mail: khoha_yury@ukr.net, https://orcid.org/0000-0002-8997-9766
c e-mail: oleksandr.lyubchak@gmail.com, https://orcid.org/0000-0002-0700-6929

Abstract

The paper considers the role of pore structure in the formation of local thermobaric conditions that may support methane generation in fossil organic matter through chain free-radical reactions. The gas–organic matter system is treated as a heterogeneous dispersed medium in which nano-, micro- and mesopores cannot be described only by bulk pressure and temperature. A dimensionless pore-pressure coefficient π = Pp/P∞ is used, where Pp is the pore pressure and P∞ is the geostatic pressure. The value π = 1 corresponds to equality between pore and geostatic pressures, whereas π < 1 indicates a pore-pressure deficit; therefore, 1 − π can be interpreted as a relative measure of rarefaction. Model data are analysed for pore diameters of 0.5, 1, 2, 5, 10, 20, 50, 100 and 1000 nm within the depth range 0–10 km. Additional trends are discussed for peat and brown coal, medium-rank coal and anthracite under heat flows of 40 and 100 mW/m2. The results show that pore size is the main factor controlling the deviation of pore pressure from geostatic pressure. In pores of 0.5–2 nm, π remains far below unity even at a depth of 10 km, whereas pores of 100–1000 nm approach a quasi-equilibrium state. A higher heat flow slightly lowers π in small pores and can promote the formation of free radicals, but this effect is secondary to the geometric restriction imposed by pore size and shape. The evolution from peat and brown coal to anthracite is therefore interpreted not only as a change in sorption capacity and transport properties, but also as a change in the abundance of local pore domains favourable to the mechanical destruction of organic matter, radical stabilization, and methane generation. The proposed interpretation links pore-scale pressure heterogeneity with the kinetics of homolytic reactions and provides a basis for further quantitative modelling of methane formation in a three-phase coal matrix.

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Keywords

coal, peat, anthracite, porosity, methane, pore pressure, rarefaction, free radicals, geostatic pressure, heat flow

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Received: April 21, 2026
Accepted: May 08, 2026
Published: May 29, 2026

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INCREASE OF HYDROCARBON PRODUCTION FROM RESERVOIR ROCKS FORMED IN THIN-LAYERED NEOGENE DEPOSITS OF THE BILCHE-VOLYTSKA AREA OF THE FORECARPATHIAN

Home > Archive > No. 3–4 (199–200) 2025 > 5–12

Geology & Geochemistry of Combustible Minerals No. 3–4 (199–200) 2025, 5–12

https://doi.org/10.15407/ggcm2025.199-200.005

Dmytro FEDORYSHYN1, Oleksandr TRUBENKO2, Serhii FEDORYSHYN3, Taras LINKO4

1, 2, 3 Ivano-Frankivsk National Technical University of Oil and Gas, Ivano-Frankivsk, Ukraine,
e-mail: 1dmytro.fedoryshyn@nung.edu.ua; 2geotom@nung.edu.ua; 3serhii.fedoryshyn@nung.edu.ua
4 JSC “Tysmenytsiagas”, Tysmenytsia, Ukraine,
e-mail: 4taras.lenko-a103-23@nung.edu.ua

Abstract

The paper addresses to the topical scientific and practical issue of enhancing the efficiency of hydrocarbon recovery from reservoir rocks formed in thin-bedded Neogene deposits of the Bilche-Volytska zone in the Precarpathian Basin. The reservoirs in this region are characterized by complex lithological structure, significant layering, variability in granulometric composition, and generally low filtration and storage properties. An additional complicating factor is the high heterogeneity of the strata, which manifests itself in both horizontal and vertical directions, significantly affecting the efficiency of oil and gas extraction using traditional methods.

The paper provides a detailed analysis of the geological prerequisites for the formation of thin-bedded sandstone-siltstone complexes, including their petrophysical characteristics, such as porosity, permeability, cementation type, and fluid saturation degree. Considerable attention is paid to the study of the filtration properties of rocks in the context of the spatial variability of reservoir parameters that determine the productive potential of wells. The influence of structural and tectonic factors on the formation of traps and the distribution of reservoir zones is considered separately.

The main factors limiting well yields in such geological conditions are analyzed, and possible ways to optimize development are considered. Improving geological and geophysical models, applying modern intensification methods, in particular hydraulic fracturing and acid treatment, as well as introducing technologies for detailed zoning of productive intervals, are promising areas for improving production efficiency. The work emphasizes the importance of a comprehensive approach that combines geological analysis, laboratory research, and modelling of filtration processes to ensure the rational and efficient development of resources in this complex category of reservoirs.

Full Text

Keywords

rock, pore space, porosity, electrical resistivity, clay content

Referenses

Fedyshyn, V. O. (2005). Nyzkoporysti porody-kolektory hazu promyslovoho pryznachennia. Kyiv: UkrDHRI. [in Ukrainian]

Fedoryshyn, D. D., Fedoryshyn, S. D., Starostin, A. V., & Koval, Ya. M. (2006). Prychyny nyzkoomnosti porid-kolektoriv ta otsinka kharakteru yikh nasychennia v umovakh naftohazovykh rodovyshch Ukrainy. Rozvidka ta rozrobka naftovykh i hazovykh rodovyshch, 3, 35–40. [in Ukrainian]

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ASSESSMENT OF THE DYNAMICS OF WATER-OIL CONTACTS AND ESTABLISHMENT OF EFFECTIVE THICKNESSES ACCORDING TO THE RESULTS OF COMPREHENSIVE GEOPHYSICAL RESEARCH

Home > Archive > No. 3–4 (191–192) 2023 > 31–36

Geology & Geochemistry of Combustible Minerals No. 3–4 (191–192) 2023, 31–36

https://doi.org/10.15407/ggcm2023.191-192.031

Dmytro FEDORYSHYN1, Ihor MYKHAILOVSKYI2, Serhii FEDORYSHYN3, Oleksandr TRUBENKO4

1, 3, 4 Ivano-Frankivsk National Technical University of Oil and Gas, Ivano-Frankivsk, Ukraine
2 LLC “BURPROEKT”, Lviv, Ukraine
e-mail: 1dmytro.fedoryshyn@nung.edu.ua; 2burproekt@ukr.net; 3serhii.fedoryshyn@nung.edu.ua; 4geotom@nung.edu.ua

Abstract

The purpose of the work is to assess the reliability of the results of geological and geophysical studies of complex-constructed Neogene deposits by electrical methods and to develop optimally reliable approaches to the selection of hydrocarbon-saturated rocks with an assessment of their reservoir parameters. In addition, to establish the factors that affect the ambiguity of geological and geophysical conclusions in the process of research of complex lithological and stratigraphic strata, which ultimately causes the omission of reservoir rocks saturated with hydrocarbons. The obtained experimental results of the research of the core material taken from the wells of the adjacent gas condensate fields made it possible to identify the main factors and parameters that determine the filtration-capacity parameters of Neogene deposits. Based on the above, there is a need to substantiate and develop methodological aspects of the use of electrical methods to determine the nature of reservoir rock saturation and to determine the dynamics of water-gas-condensate contacts. The subject of research is the electrical parameters of water- and gas-saturated reservoir rocks. In addition, the substantiation of the effect of pressure and temperature on the performance of electrical methods in the process of researching complex-constructed Neogene reservoir rocks and the peculiarities of the dynamics of changes in water-oil and gas-water contacts. The decrease in oil and gas production from complex geological sections is due to both economic and technological factors that arise in the process of researching the lithological and stratigraphic strata of the Bilche-Volytsa zone. The geological structure of the above-mentioned territories is extremely complex and represents, in particular in the Bilche-Volitsa zone, a classically expressed wing of the platform type, weakly dislocated by upper Miocene molasses.

Full Text

Keywords

geophysical studies of monomictic and polymictic reservoir rocks of complex structure, gamma spectrometry, litho-stratigraphic section, clay content, water saturation, porosity, resistivity

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