scholarly journals Secondary alterations of deep buried Lower Carboniferous terrigenous rocks in some areas of the Dnieper-Donets basin

2019 ◽  
Keyword(s):  
Influencing Factors ◽  
Pore Space ◽  
Great Depth ◽  
Donets Basin ◽  
Reservoir Properties ◽  
Reservoir Rocks ◽  
Terrigenous Rocks ◽  
Porosity And Permeability ◽  
Hydrocarbon Deposits ◽  
Epigenetic Processes

Problematics. Due to the ambiguous understanding of the nature and void space distribution within reservoir rocks, prediction of prospective deep buried and low permeable reservoirs becomes more uncertain. There are many factors influencing on the pore space, such as primary rock composition, hydrogeological regime, tectonic processes, geological time, epigenetic processes etc. Moreover, in explanation of different factors the influence of secondary reservoirs formation, systematization problems become more essential. Either, it is important to identify ‘working’ conditions of influencing factors to make the prediction of hydrocarbon deposits at great depth more certain. Finding universal criteria of prospective secondary reservoir rocks identification will allow us to enhance the discovery rate of deep buried hydrocarbon deposits. Analysis of previous studies. Many researches were devoted to epigenetic processes in the second part of XXth century. There were described major secondary alterations which may occur at great depth. Recent publications showed the expansion of previous knowledge about epigenetic processes and their influence on the secondary deep buried reservoir formation. Some scientists state that major influencing factors on reservoir quality are tectonic and primary mineral composition, others bring epigenetic imposed processes to the top of influencing factors. Purpose. The purpose of the research is to study secondary alterations and find possible zonation based on the alteration intensity of Carboniferous (Viséan and Serpukhovian) rocks within Central part of the Dnieper-Donets basin. Methods. During this research we studied 43 thin sections of Carboniferous sandstones from cores of Central part of the Dnieper-Donets basin, using polarizing microscope. Alteration stage analyses were used for determination of mineral sequence transformations. Results. Carboniferous (Viséan and Serpukhovian) sandstones discovered by deep wells within Solokhivsko-Dykanskyi and Berezivsko-Kotelevskyi archs in Central part of the Dnieper-Donets depression have been studied. Microscopic studies have shown widespread development of imposed epigenetic alterations in terrigenous rocks. The involvement of laboratory evaluation of porosity and permeability, as well as the values of formation temperatures, allowed us to determine the main trends of secondary processes effect on reservoir properties of rocks. It is shown that the development of secondary microfracturing, kaolinitization and sideritization increases the value of porosity and permeability. Dissolution, regeneration and redeposition of quartz are accompanied by calcitization and lead to the significant decrease of the reservoir properties of terrigenous rocks and formation of secondary epigenetic seals. Sideritization facilitates the development of secondary reservoirs at great depth, meanwhile calcitization leads to decrease of the pore space. Bitumoids and pyrite presence may be the evidence of hydrocarbon migration process. Combination of the research results with thermobaric data retrieved directly from borehole measurements as well as theoretically calculated on Bilske gas condensate field shows that formation of epigenetic seal in the temperature interval of 110-120 °C is caused by quartz dissolution and intensive calcitization of terrigenous rocks. Consequently, secondary reservoir rocks below the epigenetic seal have local spreading caused by microfracturing, sideritization and calcitization. Specific secondary sandy reservoirs of Berezivske gas condensate field are located within 110 and 120 °C isotherm. They occurred in acid environment leading to dissolution of calcite cement and intense sandstone kaolinitization. Such favorable conditions for secondary porosity formation may occur as a result of possible tectonic movements inversion which triggered the development of regressive epigenesis.

scholarly journals PETROGRAPHIC CHARACTERISTICS OF THE RESERVOIR ROCKS IN THE BAT-UPPER JURASSIC DEPOSITS OF THE SOUTH OF WESTERN-SIBERIAN PETROLEUM BASIN

2019 ◽  
Vol 2 (1) ◽  
pp. 25-31
Author(s):  
Lyudmila Vakulenko ◽  
Aleksey Popov ◽  
Sergey Rodyakin ◽  
Evgeniy Khabarov ◽  
Peter Yan
Keyword(s):  
Oil And Gas ◽  
Upper Jurassic ◽  
The South ◽  
Reservoir Properties ◽  
Petrographic Composition ◽  
Reservoir Rocks ◽  
Regional Sources ◽  
Porosity And Permeability ◽  
Maximum Parameters ◽  
Petroleum Basin

The features of the petrographic composition of the bath-upper Jurassic silt-sand rocks exposed by wells in the South of the West Siberian oil and gas basin are considered. The study is focused on the parameters that had a significant influence on the reservoir properties of rocks: granulometric and mineral-petrographic composition of the clastic part of rocks, cement content, structure and composition. Some conclusions are drawn on the spatial distribution of rocks of different composition within the subisochronous sedimentary complexes. It is assumed that significant variations in their composition are caused by a complex combination of varying degrees of interdependent factors: influence of local and regional sources of clastic material, peculiarities of redistribution of material during its transportation and sedimentation, and post-sedimentation changes. Most variable values of reservoir properties, with a recorded maximum parameters of porosity and permeability are obtained for the rocks of Medium-Upper Oxford complex on Verkhnetarskaya, Dedovskaya, Basinskaya, Veselovskaya, to a lesser extent, Kasmanskaya, Vostochnaya and Tai-Dasskaya drilling sites.

scholarly journals Insight into Heterogeneous Calcite Cementation of Turbidite Channel-Fills from UAV Photogrammetry

Geosciences ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 236 ◽  
Author(s):  
Mattia Marini ◽  
Giovanna Della Porta ◽  
Fabrizio Felletti ◽  
Benedetta Marcella Grasso ◽  
Marica Franzini ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Volume Fraction ◽  
Pore Space ◽  
Burial Depth ◽  
Channel Axis ◽  
Reservoir Properties ◽  
Hydrocarbon Reservoir ◽  
Cumulative Volume ◽  
Porosity And Permeability ◽  
Calcite Cement

Diagenesis is a key controlling factor on sandstone porosity and permeability. Understanding type, paragenetic sequence and spatial patterns of cements is thus important for assessing sandstone hydrocarbon reservoir properties. In this study Unmanned Aerial Vehicle (UAV) photogrammetry is used to evaluate the shape and spatial distribution of calcite concretions developed within the sand-prone fill of a turbidite channel. The studied channel-fill is entrenched into hemipelagic marlstones and include a lower conglomeratic sandstone loaded with marlstone rip-ups and an upper fill featuring a range of turbidite bed types, which, up-section and off the channel axis, are progressively finer grained and less amalgamated. Concretion shape analysis highlighted a continuum of equant to oblate shapes with flat-lying major axes and a cumulative volume fraction of ca. 22%. Equant to sub-equant concretions are ubiquitous and occur at different heights within beds, often developing around marlstone rip-ups. Conversely, elongated concretions are either strata-bound concretions or completely cemented beds which become volumetrically dominant up section and off the channel axis. The interparticle pore-space of concretions represents on average ca. 22% and is tightly filled by poikilotopic and blocky calcite cement precipitated near to maximum burial depth, whereas host sandstones lack calcite cements and show smectite clay cement and an average preserved porosity of ca. 15%. The oxygen and carbon isotopes of calcite cements point to the marlstone as the main source of carbonate ions, suggesting concretions developed during burial by either diffusion from rip-ups and mud caps or recrystallization of, matrix micrite. Results suggest that the process by which the carbonate-rich component was eroded from the substrate and trapped within the channel-fill is a key control on spatial distribution of calcite concretions, likely to reflect on spatial variability of reservoir properties.

scholarly journals Liquid and Gas Corrected Permeability Correlation for Heterogeneous Carbonate Reservoir Rocks

2020 ◽  
pp. 36-50
Author(s):  
Sadonya Jamal Mustafa ◽  
Fraidoon Rashid ◽  
Khalid Mahmmud Ismail
Keyword(s):  
Gas Permeability ◽  
Carbonate Reservoir ◽  
Reservoir Rock ◽  
Reservoir Properties ◽  
Reservoir Rocks ◽  
Rock Types ◽  
Liquid Permeability ◽  
Porosity And Permeability ◽  
Permeability Distribution ◽  
Reservoir Type

Permeability is considered as an efficient parameter for reservoir modelling and simulation in different types of rocks. The performance of a dynamic model for estimation of reservoir properties based on liquid permeability has been widely established for reservoir rocks. Consequently, the validated module can be applied into another reservoir type with examination of the validity and applicability of the outcomes. In this study the heterogeneous carbonate reservoir rock samples of the Tertiary Baba Formation have been collected to create a new module for estimation of the brine permeability from the corrected gas permeability. In addition, three previously published equations of different reservoir rock types were evaluated using the heterogenous carbonate samples. The porosity and permeability relationships, permeability distribution, pore system and rock microstructures are the dominant factors that influenced on the limitation of these modules for calculating absolute liquid permeability from the klinkenberg-corrected permeability. The most accurate equation throughout the selected samples in this study was the heterogenous module and the lowest quality permeability estimation was derived from the sandstone module.

scholarly journals Evaluation of the geological factors impact on capacity and filtration properties of terrigenuous reservoirs of the Pre-Carpathian foredeep

2018 ◽  
pp. 25-37
Author(s):  
S. S. Kurovets ◽  
І. V. Artym
Keyword(s):  
Mineral Composition ◽  
Texture Features ◽  
Reservoir Properties ◽  
Terrigenous Rocks ◽  
Carpathian Foredeep ◽  
Porosity And Permeability ◽  
Geological Factors ◽  
Carbonate Material ◽  
Clayey Rocks ◽  
Filtration Properties

The following main geological factors that determine the reservoir properties of the terrigenous rocks of the Pre-Carpathian foredeep were identified, namely: mineral composition, structural and texture features, and thermobaric factors. The mineral composition of the rock-forming minerals, the shape, the size of the fragmented grains and pores, their mutual placement, the type of fluid and the thermodynamic state determine the reservoir properties of terrigenous rocks. The best reservoirs are sandstones, compiled with larger and sorted grains. The increase of clay and carbonate material sharply worsens the reservoir properties of rocks. Sealing and secondary processes (sieving, calcifying, pyrolysis) negatively affect the reservoir properties of rocks, reduce their porosity and permeability. Some dependencies were identified. These dependencies make it possible to predict the maximum porosity of sandstones, depending on their immersion in depth. The given porosity data of sandy-clayey rocks shows, that sorted quartz sandstones with insignificant contents of clayey and carbonate materials have greater intergranular porosity and permeability at great depths.

Clay mineralogy of Carboniferous sandstone reservoirs, onshore and offshore UK

Clay Minerals ◽  
2006 ◽  
Vol 41 (1) ◽  
pp. 417-432 ◽  
Author(s):  
H. F. Shaw
Keyword(s):  
Clay Mineralogy ◽  
Clear Correlation ◽  
Reservoir Properties ◽  
Depositional Facies ◽  
Permeability Characteristics ◽  
Reservoir Rocks ◽  
Porosity And Permeability ◽  
Reservoir Porosity ◽  
Sandstone Reservoirs ◽  
Diagenetic History

AbstractThe distribution and origin of clay minerals in Carboniferous sandstone reservoir rocks, onshore and offshore UK, is reviewed using both published and unpublished sources. The clay mineralogy for many of the Carboniferous reservoir sands tends to be similar, with the detrital clays predominantly illitic whereas the diagenetic clay assemblages are dominated by kaolin with usually lesser amounts of illite. The main exception to this pattern is found in the Dinantian sandstones of the Clair Basin where significant amounts of smectite are present. Three stages of diagenetic kaolin formation are widely recognized. Firstly eogenetic and/or telogenetic kaolinite; secondly mesogenetic kaolin; and thirdly the partial or complete transformation of kaolinite to dickite during deep burial. In addition to the formation of diagenetic clay phases, the sandstone reservoirs also display a complex diagenetic history involving cementation and dissolution processes. These have affected the reservoir properties of the sandstones but the depositional facies architecture still exerts a major recognizable influence on reservoir porosity-permeability characteristics. The abundance of kaolin cements shows no clear correlation with variations in porosity and permeability for Carboniferous reservoirs. Pore- filling smectite affects reservoir porosity and permeability in the Dinantian of the Clair Field, and could be a potential source of serious reservoir damage arising from swelling.

scholarly journals The Extent of Homogeneity in the Distribution of Petrophysical Properties that Affecting the Primary and Enhanced Oil Recoveries of Reservoir Rocks in Zubair Formation of South Iraq

2008 ◽  
Vol 5 (3) ◽  
pp. 383-386
Author(s):  
Baghdad Science Journal
Keyword(s):  
Petrophysical Properties ◽  
Central Tendency ◽  
Reservoir Properties ◽  
High Quality ◽  
Reservoir Rocks ◽  
Regionalized Variables ◽  
Reservoir Property ◽  
South Iraq ◽  
Porosity And Permeability ◽  
Permeability Data

Records of two regionalized variables were processed for each of porosity and permeability of reservoir rocks in Zubair Formation (Zb-109) south Iraq as an indication of the most important reservoir property which is the homogeneity,considering their important results in criterion most needed for primary and enhanced oil reservoirs.The results of dispersion treatment,the statistical incorporeal indications,boxes plots,rhombus style and tangents angles of intersected circles indicated by confidence interval of porosity and permeability data, have shown that the reservoir rocks of Zubair units (LS),(1L) and (DJ) have reservoir properties of high quality,in contrast to that of Zubair units (MS) and (AB)which have reservoir properties of less quality than the rest.In addition,the co- efficient of the central tendency of permeability data for the reservoir rocks have indicated the homogeneity,systematic and normal distribution, in contrast to porosity data of (DJ) & (AB) units that follow a distribution which predominate in difference and heterogeneity in their values.

Diagenetic peculiarities of potential Lower Jurassic reservoir sandstones, Troms 1 area, Off Northern Norway, and their tectonic significance

Clay Minerals ◽  
1986 ◽  
Vol 21 (4) ◽  
pp. 565-584 ◽  
Author(s):  
P. Riches ◽  
I. Traub-Sobott ◽  
W. Zimmerle ◽  
U. Zinkernagel
Keyword(s):  
Pore Space ◽  
High Energy ◽  
Lower Jurassic ◽  
Burial Depth ◽  
Secondary Porosity ◽  
Reservoir Rocks ◽  
Diagenetic Alteration ◽  
Potential Reservoir ◽  
Porosity And Permeability ◽  
Reservoir Sandstones

AbstractIn the Troms 1 area, sediments of Early to Middle Jurassic age, ranging from alluvial plain deposits at the base, passing through coastal plain/tidal flat sediments up into high-energy nearshore shallow-marine sands, mark a transgression. The sandstones, classified as mineralogically and texturally mature quartz-arenites, are potential reservoir rocks in the eastern part of the area. The apparent supermaturity, however, is of secondary origin because unstable detrital components were dissolved during diagenesis. The succession of complex diagenetic processes was: (i) mechanical compaction and simultaneous pressure solution, (ii) partial dissolution with corrosion of detrital quartz and dissolution of unstable fragments, (iii) silica cementation, (iv) calcite cementation, (v) partial carbonate dissolution, (vi) kaolinite/Fe-carbonate cementation in the remaining pore space. Porosity and permeability of the sandstones are controlled by the degree of silicification and by dissolution processes. Two dissolution stages led to partial ‘skeletonization’ of the detrital framework and to elimination of unstable detrital grains. The first stage was a basic process leading to corrosion of detrital quartz and creating transitory secondary porosity; the second stage was acidic leading to the present preserved secondary porosity. Diagenetic dissolution channels formed. The degree of diagenetic alteration was much higher than normally observed in sandstones of such burial depth. Hydrothermal solutions rising from deep-seated faults may have led to this unusual alteration and triggered a rift-related type of complex diagenesis.

scholarly journals Modeling the processes of deformation and destruction of the rock sample during its extraction from great depths

2021 ◽  
Vol 248 ◽  
pp. 243-252
Author(s):  
Alexey Grishchenko ◽  
Artem Semenov ◽  
Boris Melnikov
Keyword(s):  
Mechanical Properties ◽  
Oil And Gas ◽  
Rock Sample ◽  
Geological Exploration ◽  
Reservoir Properties ◽  
Critical Dimensions ◽  
Reservoir Rocks ◽  
Rock Samples ◽  
Porosity And Permeability

Article investigates the change in the geophysical properties of rocks in the process of extracting the rock sample from great depths. Evaluation of changes in effective elastic properties, porosity and permeability of rock samples during extraction was carried out by means of finite element modeling. Assessment of the critical dimensions and orientation of internal defects, leading to the destruction of the rock samples during extraction from great depths, has been made based on the methods of linear destruction mechanics. Approach that makes it possible to calculate the change in the mechanical properties, porosity and fracturing of reservoir rocks in the process of extracting the rock sample from depths to the surface is proposed. Use of refined data on the mechanical properties of recoverable rock samples makes it possible to increase the accuracy of digital geological models required for geological exploration, determination of reservoir properties and oil and gas saturation of a field, and development of oil and gas deposits. Application of such models is especially relevant at all stages of the fields development with hard-to-recover reserves.

THE BASIC TYPES OF SECONDARY CHANGES IN RESERVOIR ROCKS IN THE TERRITORY OF THE WEST SIBERIA PLATE

2015 ◽  
pp. 26-30
Author(s):  
A. V. Podnebesnykh ◽  
S. V. Kuznetsov ◽  
V. P. Ovchinnikov
Keyword(s):  
Oil Recovery ◽  
West Siberia ◽  
Recovery Factor ◽  
Change Processes ◽  
The West ◽  
Reservoir Rocks ◽  
Tectonically Active ◽  
Porosity And Permeability ◽  
Active Zones ◽  
Regional Character

On the example of the group of fields in the West Siberia North the basic types of secondary changes in reservoir rocks are reviewed. Some of the most common types of such changes in the West Siberian plate territory include the processes of zeolitization, carbonation and leaching. These processes have, as a rule, a regional character of distribution and are confined to the tectonically active zones of the earth's crust. Due to formation of different mineral paragenesises the secondary processes differently affect the reservoir rocks porosity and permeability: thus, zeolitization and carbonization promote to reducing the porosity and permeability and leaching improvement. All this, ultimately leads to a change of the oil recovery factor and hydrocarbons production levels. Study and taking into account of the reservoir rocks secondary change processes can considerably influence on placement of operating well stock and on planning of geological and technological actions.

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