The study reconstructs the Upper Devonian Domanik sedimentation conditions using geochemical studies.Domanik sediments,the subject of study,are being developed in Russia's Volga-Ural petroleum province.Core sample...The study reconstructs the Upper Devonian Domanik sedimentation conditions using geochemical studies.Domanik sediments,the subject of study,are being developed in Russia's Volga-Ural petroleum province.Core samples have been collected from the South Tatar arch and the Birskaya saddle,totaling four wells.Macroscopic description,optical microscopic petrographic examination,X-ray analysis,X-ray fluorescence analysis,inductively coupled plasma mass spectrometry(ICP-MS),simultaneous thermal analyses,scanning electronic microscopy(SEM),Rock-Eval pyrolytic studies,and correlation analysis were among the methods used in the study.Carbonate rocks,carbonate-siliceous rocks enriched with organic matter,and carbonate breccias are the main identified lithotypes.The predominant rock-forming mineral in carbonate-siliceous rocks enriched with organic matter is quartz(chalcedony)of authigenic genesis.The lack of co rrelation between organic matter concentration and quartz,as well as the results of simultaneous thermal studies and SEM,suggest that quartz is present in both biogenic and chemogenic forms.The proxies Cd/Mo and Co x Mn were used for proving variable hydrodynamic conditions in the Domanik sediments sea:sediments were deposited under both stationary and seasonal upwelling conditions.The major bioproductivity of the Domanik sea was also influenced by hydrothermal activity.The proxy(Fe+Mn)/Ti data and the results of the rock genesis evaluation using the Zn-Ni-Co triangle diagram confirm this.The presence of hydrothermal fluids not only improved primary production in the paleobasin,but it additionally provided silica,as evidenced by the strong relationship between silica and exhalation components in carbonate-siliceous rocks.Volcanic activity had a slight impact on Domanik sediment genesis.Anoxia and euxinia in the Domanik sea were indicated by proxy U/Th-TOC and V/CrTOC data,as well as behavior of U-EF and Mo-EF on the covariation plot,which influenced organic matter burial in the sediments.Simultaneously,the terrigenous intake was limited.Carbonate breccias,which are common in the Domanik sediments section,developed as a result of the gravitational transfer of carbonate fragments into the carbonate-siliceous material,which might be driven by earthquakes.展开更多
The Upper Devonian Semiluksk(Domanik)and Mendymsk carbonate successions have been identified as the most promising unconventional oil and gas deposits in Russia's Volga-Ural petroleum province.Three lithofacies we...The Upper Devonian Semiluksk(Domanik)and Mendymsk carbonate successions have been identified as the most promising unconventional oil and gas deposits in Russia's Volga-Ural petroleum province.Three lithofacies were identified:limestones,organic matter-rich siliceous carbonate,and dolomitic limestones/dolomite.Their sediments are thought to have accumulated in the relatively deep-sea shelf depositional environment.According to X-ray analysis,calcite is the most common mineral phase in the limestones.The siliceous carbonate rocks'major mineral phases were identified to be quartz,followed by calcite.The rocks have relatively poor reservoir qualities,with porosity ranging from 0.1 to 5%and permeability ranging from 0.01 to 10 mD.Petrographic examination of thin sections reveals four major types of pores:1.interparticle pores,which are abundant in all of the examined lithofacies;2.intercrystalline pores formed between dolomite crystals and the very fine components of the siliceous carbonate rocks.3.vugs as a result of leaching,and 4.fracture as a result of tectonic and/or diagenetic events.Plotting the obtained data from the petrographically examined thin sections on the ternary pore plot diagram resulted in the identification of six pore facies and their related diagenetic patterns.Pore facies 1 depicts the pores that formed during the depositional process.Pore facies 4 displays moldic pores.The vugs are represented by pore facies 6.Pore facies 2 is a mixture between pore facies 1 and pore facies 4.Pore facies 3 is a mixture between pore facies 1 and pore facies 6.Pore facies 5 is a mixture between pore facies 4 and pore facies 6.Comparing the petrographic results and the identified pore facies show that pore facies 6 have touching pores and they played the most important role in improving the reservoir quality.The pore facies 4 which have separate pores have the most influence in the reduction of the reservoir quality.The diagenetic origin secondary pores are the most pores identified in the studied carbonate section.This reflects the strong modification of the pores by the diagenetic overprinting.The massive dissolution that forms the touching vugs,and the dolomitization process are the most diagenetic processes that affect the pore system within the studied rocks.展开更多
The research objectives are to assess the possibility of using drill cutting analysis to obtain information about the mineralogical and geochemical properties of the reservoir rocks.Drill cutting samples were collecte...The research objectives are to assess the possibility of using drill cutting analysis to obtain information about the mineralogical and geochemical properties of the reservoir rocks.Drill cutting samples were collected from a vertical well that penetrated the Domanik sediments(Semiluksk Formation)in one of the oil fields in the Volga-Ural petroleum province.Thin sections from drill cuttings were examined using an optical polarizing microscope(Axio Imager A2).X-ray diffraction(XRD)analyses were performed using a Brucker D2 Phaser X-ray powder diffractometer.Thermophysical properties were studied using an STA 449 F3 Jupiter instrument.The pyrolytic studies were performed using the Rock-Eval method.Visual inspection showed that the studied sediments are alternations of carbonates and siliceous-carbonate rocks.Thin section examinations revealed that the carbonates are mainly limestone(mudstone and wackestone)and are characterized by a dense texture and up to 30%organic residues.The siliceous-carbonate rocks are dominated by siliceous mudstones and are characterized by dark colours,layered structure,and an enrichment in organic matter.XRD analyses showed that the carbonate rocks are mainly composed of calcite,dolomite,quartz,feldspar,and mica,which are minor components.The siliceous-carbonate rocks are dominated by quartz,followed by calcite,although they also contain feldspars,mica,dolomite,and pyrite as impurities.According to the simultaneous thermal analysis,the average total hydrocarbon in the carbonate and siliceous-carbonate rocks is 13.6%(for the core samples)and 11.5%(for the drill cutting samples).The content of heavy hydrocarbons in the rocks is higher than the content of light hydrocarbons,indicating the immature nature of organic matter.Kerogen is found sporadically in siliceous-carbonate rocks.According to the pyrolytic studies,average S1 is 4.4 mg/g and average S2 is 19.8 mg/g(for the core samples);average S1 is 2.1 mg/g and average S2 is 17.8 mg/g(for the drill cutting samples),which indicated that the studied sediments have very good to excellent generation potential.The average T_(max) of 425.7℃(for the drill cutting samples)and 427.9℃(for the core samples)indicate immature organic matter that generated only heavy oils.Comparing the results of the analysed drill cutting samples with the results of the analysed core analysis from the same reservoir interval in the neighbouring wells showed a good correlation,which proves that this technique is a valid tool that provides an alternative,cost-effective method to determine the rock's characteristics from drill cuttings.展开更多
The results of integrated sedimentology,petrography,and petrophysical study of the Upper Devonian(Middle Famennian)Dankovo-Lebedyansky carbonates from Southeast Tatarstan of the Volga-Ural Basin revealed a variety of ...The results of integrated sedimentology,petrography,and petrophysical study of the Upper Devonian(Middle Famennian)Dankovo-Lebedyansky carbonates from Southeast Tatarstan of the Volga-Ural Basin revealed a variety of microfacies and diagenetic events that impacted the reservoir quality.Although our earlier study documented microfacies analysis and depositional environments,none of the studies focused on diagenesis,microfacies interaction,and their controls on the studied sediment's reservoir quality.Based on petrographic and microfacies analyses,the seven identified microfacies types are peloidal grainstone MF 1,cemented bioclastic peloidal grainstone MF 2,echinoderm-concentrated packstone MF 3,algae packstone MF 4,bioclastic wackestone MF 5,whole-fossil wackestone MF 6,and dolomite MF 7.For the investigated sediments,a gently deepening carbonate ramp depositional model with an inner,middle,and outer ramp setting is proposed.The observed diagenetic events in this study include micritization,calcite cementation(six cement types),dolomitization(six dolomite types),dissolution(fabric and non-fabric-selective dissolution),compaction,and microfracturing.The identified microfacies were classified into three distinct classes based on their petrophysical characteristics.MF 1 and MF 7 are microfacies types with the best reservoir quality.MF 3 and MF 4 are microfacies types of moderate reservoir quality.MF 2,MF 5,and MF 6 are microfacies types with poor or non-reservoir quality.Calcite cementation,micritization,and compaction are the primary diagenetic modifications responsible for porosity reduction.Moldic pores created by dissolution are a significant porosityimproving process.Porosity is locally enhanced by stylolite and microfractures.Dolomitization improved reservoir quality by creating intercrystalline and vuggy porosity.Understanding the impact of microfacies and diagenesis on reservoir quality is crucial for understanding reservoir properties in nearby fields with similar settings.展开更多
The Upper Devonian,Middle Famennian Dankovo-Lebedyansky sediments in Southeast Tatarstan territory are a carbonate sequence composed of limestone and dolomite,which is important hydrocarbon reservoir units,therefore,i...The Upper Devonian,Middle Famennian Dankovo-Lebedyansky sediments in Southeast Tatarstan territory are a carbonate sequence composed of limestone and dolomite,which is important hydrocarbon reservoir units,therefore,it is necessary to conduct in-depth study on its microfacies and depositional environment.In this study,a multidisciplinary approach that combines core observation with thin section examination is used.The limestone contains abundant skeletal grains(echinoderms,foraminifera,algae,gastropods,and calcispheres),as well as non-skeletal grains(intraclasts and peloids).On the basis of detailed petrographic investigations,six sedimentary microfacies can be identified,including(i)peloidal grainstone(MF 1),(ii)cemented bioclastic peloidal grainstone(MF 2),(iii)echinodermconcentrated packstone(MF 3),(iv)algae packstone(MF 4),(v)bioclastic wackestone(MF 5),(vi)whole-fossil wackestone(MF 6),as well as dolomite or dolostone as diagenetic facies(MF 7).Based on microfacies analysis,the Dankovo-Lebedyansky sediments were deposited in three distinct sedimentary facies belts(shoal,lagoon and open marine environment).In order to reflect dispositional energy condition,the microfacies were grouped into facies associations:(i)low-energy microfacies associations including MF 5 and MF 6,(ii)moderate energy microfacies associations including MF 1,MF 2,MF 3,and MF 4.The dolomite,or diagenetic facies(MF 7),is the result of slightly to extensively dolomitization of limestone in the Dankovo-Lebedyansky sediments.Most of frequent dolostone types are euhedral planar-e and subhedral planar-s.According to petrographic characteristic of the dolostone,a seepage reflux model can be used to explain the dolomitization process of Dankovo-Lebedyansky sediments.展开更多
基金funded by the subsidy allocated to Kazan Federal University for the state assignment in the sphere of scientific activities,project No.FZSM-2023-0014。
文摘The study reconstructs the Upper Devonian Domanik sedimentation conditions using geochemical studies.Domanik sediments,the subject of study,are being developed in Russia's Volga-Ural petroleum province.Core samples have been collected from the South Tatar arch and the Birskaya saddle,totaling four wells.Macroscopic description,optical microscopic petrographic examination,X-ray analysis,X-ray fluorescence analysis,inductively coupled plasma mass spectrometry(ICP-MS),simultaneous thermal analyses,scanning electronic microscopy(SEM),Rock-Eval pyrolytic studies,and correlation analysis were among the methods used in the study.Carbonate rocks,carbonate-siliceous rocks enriched with organic matter,and carbonate breccias are the main identified lithotypes.The predominant rock-forming mineral in carbonate-siliceous rocks enriched with organic matter is quartz(chalcedony)of authigenic genesis.The lack of co rrelation between organic matter concentration and quartz,as well as the results of simultaneous thermal studies and SEM,suggest that quartz is present in both biogenic and chemogenic forms.The proxies Cd/Mo and Co x Mn were used for proving variable hydrodynamic conditions in the Domanik sediments sea:sediments were deposited under both stationary and seasonal upwelling conditions.The major bioproductivity of the Domanik sea was also influenced by hydrothermal activity.The proxy(Fe+Mn)/Ti data and the results of the rock genesis evaluation using the Zn-Ni-Co triangle diagram confirm this.The presence of hydrothermal fluids not only improved primary production in the paleobasin,but it additionally provided silica,as evidenced by the strong relationship between silica and exhalation components in carbonate-siliceous rocks.Volcanic activity had a slight impact on Domanik sediment genesis.Anoxia and euxinia in the Domanik sea were indicated by proxy U/Th-TOC and V/CrTOC data,as well as behavior of U-EF and Mo-EF on the covariation plot,which influenced organic matter burial in the sediments.Simultaneously,the terrigenous intake was limited.Carbonate breccias,which are common in the Domanik sediments section,developed as a result of the gravitational transfer of carbonate fragments into the carbonate-siliceous material,which might be driven by earthquakes.
基金This work was supported by the Ministry of Science and Higher Education of the Russian Federation under agreement No.075-15-2020-931 within the framework of the development program for a world-class Research Center“Efficient development of the global liquid hydrocarbon reserves”.The authors would like to thank the editors and reviewers of the Petroleum Research journal for their valuable comments,which helped to improve the article's quality。
文摘The Upper Devonian Semiluksk(Domanik)and Mendymsk carbonate successions have been identified as the most promising unconventional oil and gas deposits in Russia's Volga-Ural petroleum province.Three lithofacies were identified:limestones,organic matter-rich siliceous carbonate,and dolomitic limestones/dolomite.Their sediments are thought to have accumulated in the relatively deep-sea shelf depositional environment.According to X-ray analysis,calcite is the most common mineral phase in the limestones.The siliceous carbonate rocks'major mineral phases were identified to be quartz,followed by calcite.The rocks have relatively poor reservoir qualities,with porosity ranging from 0.1 to 5%and permeability ranging from 0.01 to 10 mD.Petrographic examination of thin sections reveals four major types of pores:1.interparticle pores,which are abundant in all of the examined lithofacies;2.intercrystalline pores formed between dolomite crystals and the very fine components of the siliceous carbonate rocks.3.vugs as a result of leaching,and 4.fracture as a result of tectonic and/or diagenetic events.Plotting the obtained data from the petrographically examined thin sections on the ternary pore plot diagram resulted in the identification of six pore facies and their related diagenetic patterns.Pore facies 1 depicts the pores that formed during the depositional process.Pore facies 4 displays moldic pores.The vugs are represented by pore facies 6.Pore facies 2 is a mixture between pore facies 1 and pore facies 4.Pore facies 3 is a mixture between pore facies 1 and pore facies 6.Pore facies 5 is a mixture between pore facies 4 and pore facies 6.Comparing the petrographic results and the identified pore facies show that pore facies 6 have touching pores and they played the most important role in improving the reservoir quality.The pore facies 4 which have separate pores have the most influence in the reduction of the reservoir quality.The diagenetic origin secondary pores are the most pores identified in the studied carbonate section.This reflects the strong modification of the pores by the diagenetic overprinting.The massive dissolution that forms the touching vugs,and the dolomitization process are the most diagenetic processes that affect the pore system within the studied rocks.
基金supported by the Ministry of Science and Higher Education of the Russian Federation under agreement No.075-15-2022-299 within the framework of the development program for a world-class Research Center“Efficient development of the global liquid hydrocarbon reserves”.The authors acknowledge the constructive comments of the anonymous reviewers,the associate editor,and the journal editor-in-chief Dr.Chengzao Jia.
文摘The research objectives are to assess the possibility of using drill cutting analysis to obtain information about the mineralogical and geochemical properties of the reservoir rocks.Drill cutting samples were collected from a vertical well that penetrated the Domanik sediments(Semiluksk Formation)in one of the oil fields in the Volga-Ural petroleum province.Thin sections from drill cuttings were examined using an optical polarizing microscope(Axio Imager A2).X-ray diffraction(XRD)analyses were performed using a Brucker D2 Phaser X-ray powder diffractometer.Thermophysical properties were studied using an STA 449 F3 Jupiter instrument.The pyrolytic studies were performed using the Rock-Eval method.Visual inspection showed that the studied sediments are alternations of carbonates and siliceous-carbonate rocks.Thin section examinations revealed that the carbonates are mainly limestone(mudstone and wackestone)and are characterized by a dense texture and up to 30%organic residues.The siliceous-carbonate rocks are dominated by siliceous mudstones and are characterized by dark colours,layered structure,and an enrichment in organic matter.XRD analyses showed that the carbonate rocks are mainly composed of calcite,dolomite,quartz,feldspar,and mica,which are minor components.The siliceous-carbonate rocks are dominated by quartz,followed by calcite,although they also contain feldspars,mica,dolomite,and pyrite as impurities.According to the simultaneous thermal analysis,the average total hydrocarbon in the carbonate and siliceous-carbonate rocks is 13.6%(for the core samples)and 11.5%(for the drill cutting samples).The content of heavy hydrocarbons in the rocks is higher than the content of light hydrocarbons,indicating the immature nature of organic matter.Kerogen is found sporadically in siliceous-carbonate rocks.According to the pyrolytic studies,average S1 is 4.4 mg/g and average S2 is 19.8 mg/g(for the core samples);average S1 is 2.1 mg/g and average S2 is 17.8 mg/g(for the drill cutting samples),which indicated that the studied sediments have very good to excellent generation potential.The average T_(max) of 425.7℃(for the drill cutting samples)and 427.9℃(for the core samples)indicate immature organic matter that generated only heavy oils.Comparing the results of the analysed drill cutting samples with the results of the analysed core analysis from the same reservoir interval in the neighbouring wells showed a good correlation,which proves that this technique is a valid tool that provides an alternative,cost-effective method to determine the rock's characteristics from drill cuttings.
基金supported by the Ministry of Science and Higher Education of the Russian Federation under agreement No.075-15-2022-299 within the framework of the development program for a world-class Research Center“Efficient development of the global liquid hydrocarbon reserves”.
文摘The results of integrated sedimentology,petrography,and petrophysical study of the Upper Devonian(Middle Famennian)Dankovo-Lebedyansky carbonates from Southeast Tatarstan of the Volga-Ural Basin revealed a variety of microfacies and diagenetic events that impacted the reservoir quality.Although our earlier study documented microfacies analysis and depositional environments,none of the studies focused on diagenesis,microfacies interaction,and their controls on the studied sediment's reservoir quality.Based on petrographic and microfacies analyses,the seven identified microfacies types are peloidal grainstone MF 1,cemented bioclastic peloidal grainstone MF 2,echinoderm-concentrated packstone MF 3,algae packstone MF 4,bioclastic wackestone MF 5,whole-fossil wackestone MF 6,and dolomite MF 7.For the investigated sediments,a gently deepening carbonate ramp depositional model with an inner,middle,and outer ramp setting is proposed.The observed diagenetic events in this study include micritization,calcite cementation(six cement types),dolomitization(six dolomite types),dissolution(fabric and non-fabric-selective dissolution),compaction,and microfracturing.The identified microfacies were classified into three distinct classes based on their petrophysical characteristics.MF 1 and MF 7 are microfacies types with the best reservoir quality.MF 3 and MF 4 are microfacies types of moderate reservoir quality.MF 2,MF 5,and MF 6 are microfacies types with poor or non-reservoir quality.Calcite cementation,micritization,and compaction are the primary diagenetic modifications responsible for porosity reduction.Moldic pores created by dissolution are a significant porosityimproving process.Porosity is locally enhanced by stylolite and microfractures.Dolomitization improved reservoir quality by creating intercrystalline and vuggy porosity.Understanding the impact of microfacies and diagenesis on reservoir quality is crucial for understanding reservoir properties in nearby fields with similar settings.
基金supported by the Ministry of Science and Higher Education of the Russian Federation under agreement No.075-15-2022-299 within the framework of the development program for a world-class Research Center“Efficient development of the global liquid hydrocarbon reserves”.
文摘The Upper Devonian,Middle Famennian Dankovo-Lebedyansky sediments in Southeast Tatarstan territory are a carbonate sequence composed of limestone and dolomite,which is important hydrocarbon reservoir units,therefore,it is necessary to conduct in-depth study on its microfacies and depositional environment.In this study,a multidisciplinary approach that combines core observation with thin section examination is used.The limestone contains abundant skeletal grains(echinoderms,foraminifera,algae,gastropods,and calcispheres),as well as non-skeletal grains(intraclasts and peloids).On the basis of detailed petrographic investigations,six sedimentary microfacies can be identified,including(i)peloidal grainstone(MF 1),(ii)cemented bioclastic peloidal grainstone(MF 2),(iii)echinodermconcentrated packstone(MF 3),(iv)algae packstone(MF 4),(v)bioclastic wackestone(MF 5),(vi)whole-fossil wackestone(MF 6),as well as dolomite or dolostone as diagenetic facies(MF 7).Based on microfacies analysis,the Dankovo-Lebedyansky sediments were deposited in three distinct sedimentary facies belts(shoal,lagoon and open marine environment).In order to reflect dispositional energy condition,the microfacies were grouped into facies associations:(i)low-energy microfacies associations including MF 5 and MF 6,(ii)moderate energy microfacies associations including MF 1,MF 2,MF 3,and MF 4.The dolomite,or diagenetic facies(MF 7),is the result of slightly to extensively dolomitization of limestone in the Dankovo-Lebedyansky sediments.Most of frequent dolostone types are euhedral planar-e and subhedral planar-s.According to petrographic characteristic of the dolostone,a seepage reflux model can be used to explain the dolomitization process of Dankovo-Lebedyansky sediments.
