Gas Bearing Complexes Research Articles

Geochemistry and origin of natural gas in the arctic area of West Siberia

Results obtained in the studies of gas composition in the hydrocarbon pools of the Jurassic–Cretaceous sediments in the Arctic regions of West Siberia are reported. The specific features of gas composition in hydrocarbon pools are shown. The main features of the vertical and lateral gas zoning in the Aptian–Albian–Cenomanian, Berriasian–Hauterivian and Jurassic oil and gas bearing complexes are revealed. Generalization of the data on the geochemistry of hydrocarbon gases (the features of component composition, the isotope composition of methane), along with the published data of the geological and geochemical investigation of the Arctic regions of West Siberia, allows us to consider the highly mature Triassic–Middle Jurassic coaly matter as the source of the dry hydrocarbon gases of the Lower and Middle Jurassic complex. Either the Triassic–Middle Jurassic sediments or the Upper Jurassic beds, enriched with the aquatic organic matter, could be involved in the formation of Upper Jurassic and Lower Cretaceous pools. The low-maturity terrestrial (carbonaceous) organic matter of the Cretaceous sediments generated the major amount of light-isotope gases in the Aptian–Albian–Cenomanian sediments. In addition, the source of those gases could be methane formed during oil biodegradation.

Oil and gas complexes as a material expression of geofluid dynamic systems

The purpose of the present research is to analyze the geofluid dynamic concept of oil and gas formation. The research uses the author's data on the structure, composition and thickness of multi-aged oil and gas complexes of the Siberian platform (Russia). The oil and gas complexes identified as a result of the integrated geological, geochemical and geophysical studies carried out under oil and gas geological zoning and operational work are presented as a material expression of geofluid dynamic systems. Any geofluid dynamic system includes hydrocarbon generation centers, oil and gas migration routes, types of reservoirs and traps, lithological composition of reservoir rocks and reservoir cap rocks Also it is controlled by a favorable combination of their appearance in geological time and space. An ordinary fluid dynamic system is presented by hydrocarbon solutions generated by oil and gas generation centers, which are examples of a trivial defluidization of oil and gas source rocks of a sedimentary basin. This study allowed to be the first who has identified the elements of multi-age geofluid dynamic systems, presented their material expression in the form of multi-age oil and gas bearing complexes as well as analyzed the composition of hydrocarbons on the example of individual deposits of variousoil and gas-bearing areas. Besides, possible generation centers of hydrocarbon fluids and ways of their migration were investigated. Oil fields of different ages of the oil and gas bearing provinces of the Siberian Platform feature different composition and density, whereas according to numerous available data, they belong to a single genetic type, which is characterized by the predominance of methane hydrocarbons.

Oil and gas bearing complexes of the pre jurassic deposits of Southern Mangistau and their characteristics

The article is devoted to the features of the geological structure on the example of the analysis of the pre-Jurassic complex of the South Mangistau with recommendations for determining the further direction of prospecting and exploration.

Evaluation of hydrocarbon resources of the Devonian terrigenous rock basin of Perm Region

The geological structure of the Devonian terrigenous complex within the Bashkirian arch located in the well-explored southern part of Perm Krai has been considered in the paper. Due to the limited extent and complex structure of the bulk of reservoir rock in the prospective horizons, these deposits are explored unevenly, usually alongside with the overlying oil and gas bearing complexes. On the basis of the performed analysis of systematic data, the authors justify quantitative parameters for evaluation of non-localized resources after the method of comparative geological analogies in the Devonian terrigenous deposits. The estimated quantity of hydrocarbon resources in the territory under study unequivocally defines it as prospective for exploration and discovery of reserves in the Devonian oil and gas bearing complex. Therefore, the authors have identified areas for priority prospect evaluation survey taking into account the extent of the most promising facies zones of deltaic channels and beach bars.

Main directions of searching for hydrocarbons in Nadym-Pursk oil and gas region

Nadym-Pursk oil and gas region has been one of the main areas for the production of hydrocarbon raw materials since the sixties of the last century. A significant part of hydrocarbon deposits is at the final stage of field development. An increase in gas and oil production is possible subject to the discovery of new fields. The search for new hydrocarbon deposits must be carried out taking into account an integrated research approach, primarily the interpretation of seismic exploration, the creation of geological models of sedimentary basins, the study of geodynamic processes and thermobaric parameters. Statistical analysis of geological parameters of oil and gas bearing complexes revealed that the most promising direction of search are active zones — blocks with the maximum sedimentary section and accumulation rate. In these zones abnormal reservoir pressures and high reservoir temperatures are recorded. The Cretaceous oil and gas megacomplex is one of the main prospecting targets. New discovery of hydrocarbon deposits are associated with both additional exploration of old fields and the search for new prospects on the shelf of the north. An important area of geological exploration is the productive layer of the Lower-Berezovskaya subformation, in which gas deposits were discovered in unconventional reservoirs.

OIL AND GAS COMPLEXES OF THE ALDANO-MAY OIL AND GAS REGION

The article discusses the history of the geological study of the Aldan-Maya oil and gas region, during which numerous signs of oil and gas potential were identified. The description of oil and gas bearing complexes of sedimentary strata is given. It is shown that the prospects for the discovery of new oil and gas fields in the Aldan-Maya oil and gas bearing area were assessed quite high.

CLASTIC HETEROFACIAL SEDIMENTS IN THE SEDIMENTARY COMPLEXES OF THE SOUTHERN OIL AND GAS REGION OF UKRAINE

In this article the author carried out sedimentary and genetic modeling of facies parameters within heterogeneous geological bodies based on the analysis of geological and geophysical materials in the Southern Ukrainian oil and gas region. Special attention was paid to clastic facies and parameters demonstrating the degree of heterogeneity and a wide range of facial settings of the sedimentation basin. The data from lithological, geochemical, and geophysical field studies of wells was interpreted to predict hydrocarbon traps. This resulted in the facial diagnostic of the groups of geological bodies of clastic rocks coexisting with sediments of both tectonic and ridge morphological structure of the study area. Such diagnostics allowed us to build a prognostic lithologicfacial (sedimentation) section. Based on the modeling of the Vendian top (Vendian is a stratigraphic unit partially corresponding to Ediacaran) and the Jurassic base, a schematic map of the Paleozoic sediments was constructed for the first time, which made it possible to identify zones of the potential distribution of the former reef structures. The article presents the spatial forecast of hydrocarbon reservoir distribution in geological bodies of oil and gas bearing complexes within the PreDobruja Trough. The data allow forecasting a large number of traps, mainly small ones, formed by clusters of cavernous dolomites, limestones, and mixed rocks confined to certain cyclical elements and, in particular, associated with diastems. Most of such traps are caused by metasomatic dolomitization and paleokarst.

Estimation of prospects of oil and gas production of Barents Sea shelf by results of seismic measurement by 3D common dept point method

The article shows the tectonic confinement of the research area and its position from the point of view of petroleum geological classification, and the main oil and gas bearing complexes are identified. According to the Triassic, Jurassic-Barremian and Aptian-Albian-Cenomanian oil and gas bearing complexes, a seismic-geological model was given, the conditions for the formation of deposits were considered, prospective objects were identified, and the optimal volume of exploratory drilling was planned. The complex of features indicates the presence of vertical migration of hydrocarbons, which contribute to the formation of secondary hydrocarbon deposits in the Cretaceous section.

Forecasting of reservoir pressures of oil and gas bearing complexes in northern part of West Siberia for safety oil and gas deposits exploration and development

In the paper the features of reservoir pressures changes in the northern part of West Siberian oil-and gas province are described. This research is based on the results of hydrodynamic studies in prospecting and explorating wells in Yamal-Nenets Autonomous District. In the Cenomanian, Albian, Aptian and in the top of Neocomian deposits, according to the research, reservoir pressure is usually equal to hydrostatic pressure. At the bottom of the Neocomian and Jurassic deposits zones with abnormally high reservoir pressures (AHRP) are distinguished within Gydan and Yamal Peninsula and in the Nadym-Pur-Taz interfluve. Authors performed the unique zoning of the territory of the Yamal-Nenets Autonomous District according to the patterns of changes of reservoir pressures in the section of the sedimentary cover. The performed zoning and structural modeling allow authors to create a set of the initial reservoir pressures maps for the main oil and gas bearing complexes of the northern part of West Siberia. The results of the survey should improve the efficiency of exploration drilling by preventing complications and accidents during this operation in zones with abnormally high reservoir pressures. In addition, the results of the study can be used to estimate gas resources within prospective areas of Yamal-Nenets Autonomous District.

Models of hydrocarbon systems in the Russian Platform–Ural junction zone

The paper presents results of the numerical basin modeling of hydrocarbon generation-accumulation systems in four oil- and gas-bearing complexes in the Russian Platform–Ural junction zone: Lower Devonian–Frasnian, Frasnian–Tournaisian, Visean–Bashkirian, and Lower Permian. For each oil- and gas-bearing complex, the study area has been ranked in terms of the petroleum potential.

Distribution of aromatic hydrocarbons in the context of sediments of oil and gas bearing complexes (on the example of Krasnoleninsky arch deposits)

On the base of unique geochemical studies of the core samples from two exploration wells interstratal movement of heavy oil hydrocarbons has been revealed in the section of Rogozhnik-ov and North-Rogozhnikov deposits of the Krasnoleninsk dome (West Siberia). Geochemical model of vertical migration of heavy oil hydrocarbons has been plotted where those compounds have been distinguished which are capable of interstratal movement, the form of migration has been proposed and the distance of movement of substances in the section has been estimated. The distance of vertical interstratal migration of aromatic hydrocarbons makes it possible to recommend their anomalous concentrations as direct prospecting criteria. Migration of oil hydrocarbons from the sedimentary cover to basement deposits has been revealed.

OIL AND GAS POTENTIAL OF SEDIMENTARY BASINS OF THE URAL-MONGOLIAN MOBILE BELT

The sedimentary basins of the Ural-Mongolian mobile belt fall into two groups: near-geosynclinal folded and intrageosynclinal folded. In the present structural plan the first group includes two planetary-scale belts of oil and gas accumulation, the Ural and Yenisey. The main regional oil- and gas-bearing complexes of the Ural belt are transgressive middle Devonian-early Frasnian clastic rocks, containing up to 18-20% initial oil and gas reserves in categories A + B + Ci + C2; regressive-transgressive early-middle Visean clastic formations (12-15%); inundational Bashkirian-Visean (22-25%) and Late Carboniferous-Early Permian (21-25%) carbonate rocks. The main regional oil- and gas-bearing complexes of the Yenisey belt are related to mainly clastic transgressive Vendian-early Cambrian rocks (40-50% of initial potential hydrocarbon reserves) and inundational Cambrian evaporite-carbonate formations (up to 25%). All the epi-geosynclinal sedimentary basins belong to the second group; they are mainly heterogenet...

Evolution of West Siberian Petroliferous in the Phanerozoic

Evolution of a basin implies interaction of two general processes: the process of crust collapse with regeneration of geosyncline belts, and the process of cratonization of the crust. The process of geosyncline belt regeneration with partial displacement across the area occurred three times in western Siberia. The first displacement is dated as long as 1.6 Ga, the second one took place at 650 Ma, and the third at 500 Ma. There were three cratonizations of the first rank: 680 Ma, 520 Ma, and 250 Ma. The last, Hercynian, cratonization has been more intensive in the southern part of the region and has resulted in Triassic-Middle Jurassic taphrogenesis on the background of arched uplifts. Organic-matter transformation and formation of oil and gas pools repeated in the Paleozoic and Mesozoic. In the Cenozoic, the formation of oil and gas pools took place only locally. The process intensity varied depending on the basin geodynamics and geothermal regime. This caused a considerable range of oil and gas interval and resources in different regions. The distribution of hydrocarbon pools is of regular character only in separate oil- and gas-bearing complexes, except the secondary pools which are confined to Paleozoic basement weathered rocks occurring in allmore » areas of the petroliferous basin. The largest hydrocarbon pools of Lower Jurassic deposits are more common in the western regions, and pools of Upper Jurassic deposits occur in the eastern ones.« less

Lower Cretaceous stratigraphic oil- and gas-bearing complexes of the West Siberian Platform

Lower Cretaceous stratigraphic oil- and gas-bearing complexes of the West Siberian Platform