This study analyzes Brazilian stromatolites in Lagoa Salgada,serving as analogs for pre-salt rocks in the Santos and Campos basins.Despite their excellent petrophysical properties,such as high porosity and permeabilit...This study analyzes Brazilian stromatolites in Lagoa Salgada,serving as analogs for pre-salt rocks in the Santos and Campos basins.Despite their excellent petrophysical properties,such as high porosity and permeability,these reservoirs present challenges in fluid flow modeling and simulation.The research investigates various factors influencing the development of carbonate reservoirs,including diagenetic processes employing several techniques,such as microcomputed tomography(micro-CT)and digital rock physics(DRP),to study petrophysical and geological characteristics.Additionally,through numerical simulations,the properties of fluid flow in different microfacies of stromatolites are estimated,with particular emphasis on understanding and highlighting changes in the direction of fluid flow in the three characterized microfacies.These findings offer crucial insights into optimizing oil and gas exploration and production techniques in carbonate reservoirs,providing a comprehensive understanding of the dynamics of fluid transport in porous media,especially in terms of directional changes within stromatolites.展开更多
The Tigris-Euphrates is a continental-scale fluvial system,around 2800 km in length,which drains over 1 million km2 of SWAsia.The system originated in the Late Miocene and developed into the principal axial drainage s...The Tigris-Euphrates is a continental-scale fluvial system,around 2800 km in length,which drains over 1 million km2 of SWAsia.The system originated in the Late Miocene and developed into the principal axial drainage system of the region,which follows broad regional structural features of the Mesopotamian Foreland Basin.Good preservation and outcropping of the Pliocene and Quaternary Euphrates deposits yield a viable local analogue for subsurface fluvial reservoirs in the region,and for other fluvial systems that have developed in foreland basin settings.This paper documents the first detailed study of the sedimentary characteristics of these Pliocene and Quaternary fluvial deposits along the middle reaches of the present-day Euphrates in Syria.The Euphrates fluvial system developed from small and probably short-lived isolated cut-and-fill channels in the Pliocene,characterised by abundant debrite and slump facies,through to a broad meandering system at present.The Quaternary deposits represent a braided to meandering system that was more energetic than that of the modern day Euphrates.The Quaternary facies include a dominance of gravels,pebbly sands and sands as channel associations,coupled with sands,muds and paleosols representing channel abandonment,overbank and crevasse-splay associations.Channel widths,where observed,range from 50 to 500 m,and minimum fill thicknesses range from 3 to 7 m.The combined channel-fill for stacked channels is up to 25 m thick.Lateral correlation of channel elements over at least 1 km of section indicates that rapid and extensive lateral migration has occurred.Crevasse splay lobes can be identified in the overbank deposits,with a width of 30e60 m and sand thickness of 0.5e1.5 m.The geometry,nature and dimensions of these architectural elements provide a useful analogue for subsurface reservoirs.The high-energy channel facies of the Quaternary system show very good reservoir attributes,with good correlation and connectivity.At the bed-scale there is significant heterogeneity of characteristics that would impact fluid-flow for hydrocarbon production from a subsurface reservoir.However,incomplete preservation of these Quaternary fluvial deposits at outcrop remains a challenge for accurately determining the scale of sedimentary features and also the size of the paleo-river.展开更多
Natural open fractures(NOFs)in reservoir rocks are critical factors influencing permeability.Identifying these fractures and fractured zones typically involves analyzing core samples and image logs.However,core data a...Natural open fractures(NOFs)in reservoir rocks are critical factors influencing permeability.Identifying these fractures and fractured zones typically involves analyzing core samples and image logs.However,core data are limited topecific depths within the reservoir,and image log data are confined to a small number of wells.In this study,fracture facies in a carbonate reservoir(Kangan-Dalan Formation)were predicted using Formation Micro-Imager(FMl)logs,conventional well logs,and petrophysical parameters,with a machine learning algorithm.Initially,open fractures were identified in wells A and B using the FMl log.In well A,the open fractures exhibit an average dip of 61,an azimuth of N79E,and a strike direction of N11W/S11E.In well B,the fractures have an average dip of 69°,an azimuth of N26E,and a strike direction of N64W/S64E.Subsequently,fracture density logs for wells A and B were calculated,with average values of O.41and 0.33,respectively.Conventional well logs,including density(RHOB),sonic(DT),and petrophysical parameters,specifically effective porosity(PHIE),were used as input data for a Multi-Resolution Graph-Based Clustering(MRGC)algorithm,which is one of the machine learning algorithms employed in this study.Additionally,a synthetic log called FLAG,derived from the fracture density log(with values of 0 and 1 indicating the presence or absence of fractures),was incorporated into the algorithm as an associated input log.This algorithm enabled the identification of fracture facies,representing open fractures or fractured zones,in well A.To evaluate the accuracy of the algorithm,the results obtained were compared with two other clustering algorithms:Ascendant Hierarchical Clustering(AHC)and Self-Organizing Maps(SOM).Well B was used as a blind test to validate the clustering model.In this test,the clustering algorithm was applied excluding the FLAG synthetic log derived from the FMI log.The results from well B demonstrated that the developed algorithm accurately identifies fracture facies in wells lacking image log and core data.The algorithm was subsequently extended to wells C and D,which lacked core or image log data.Fractured zones in these wells were successfully identified as fracture facies.Additionally,a two-dimensional map of fracture facies thickness was generated for the study area.The developed hybrid algorithm demonstrated strong potential for generalizing to other wells in the field,enabling fracture facies modeling in both 2D and 3D.展开更多
Since long ago, indirect study of the underground layers properties has been interesting to geologists.One method for this study was seismography which gained great interest besides other tools due to thedifferent ide...Since long ago, indirect study of the underground layers properties has been interesting to geologists.One method for this study was seismography which gained great interest besides other tools due to thedifferent identity of waves and energy attraction phenomena in different layers. Vertical seismic profiling(VSP) is considered as a valuable method in oil and gas exploration. This method is used to estimate therock properties in a well. In seismic operations elastic waves are sent down to the underground. Part ofthe waves’ energy is reflected after passing through the earth layers and are received by receivers on theground level. The received data determine the situation of the underneath layers after being processed,and one of the most important applications of seismic data is in the oil and gas exploration field. Qualityfactor is one of the most important seismic detectors that shows itself apparently in VSP data results. Themost substantial purpose of this study is to investigate the frequency content of the quality factor.展开更多
基金the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior of the Ministry of Education(CAPES/MEC/BRAZIL)-Finance Code 001,Equinor Energy of Brazil Company(Project No.4600025270)the Brazilian National Agency of Petroleum,Gas,and Biofuels(ANP),and Petrobras(Project No.46000579151)+1 种基金INCT/Petroleum Geophysics for financial supportthe National Council for Scientific and Technological Development (CNPq) for their Research Grants of Productivity in Technological Development and Innovation-DT II (313522/2019-7 and 313746/ 2019-2)
文摘This study analyzes Brazilian stromatolites in Lagoa Salgada,serving as analogs for pre-salt rocks in the Santos and Campos basins.Despite their excellent petrophysical properties,such as high porosity and permeability,these reservoirs present challenges in fluid flow modeling and simulation.The research investigates various factors influencing the development of carbonate reservoirs,including diagenetic processes employing several techniques,such as microcomputed tomography(micro-CT)and digital rock physics(DRP),to study petrophysical and geological characteristics.Additionally,through numerical simulations,the properties of fluid flow in different microfacies of stromatolites are estimated,with particular emphasis on understanding and highlighting changes in the direction of fluid flow in the three characterized microfacies.These findings offer crucial insights into optimizing oil and gas exploration and production techniques in carbonate reservoirs,providing a comprehensive understanding of the dynamics of fluid transport in porous media,especially in terms of directional changes within stromatolites.
文摘The Tigris-Euphrates is a continental-scale fluvial system,around 2800 km in length,which drains over 1 million km2 of SWAsia.The system originated in the Late Miocene and developed into the principal axial drainage system of the region,which follows broad regional structural features of the Mesopotamian Foreland Basin.Good preservation and outcropping of the Pliocene and Quaternary Euphrates deposits yield a viable local analogue for subsurface fluvial reservoirs in the region,and for other fluvial systems that have developed in foreland basin settings.This paper documents the first detailed study of the sedimentary characteristics of these Pliocene and Quaternary fluvial deposits along the middle reaches of the present-day Euphrates in Syria.The Euphrates fluvial system developed from small and probably short-lived isolated cut-and-fill channels in the Pliocene,characterised by abundant debrite and slump facies,through to a broad meandering system at present.The Quaternary deposits represent a braided to meandering system that was more energetic than that of the modern day Euphrates.The Quaternary facies include a dominance of gravels,pebbly sands and sands as channel associations,coupled with sands,muds and paleosols representing channel abandonment,overbank and crevasse-splay associations.Channel widths,where observed,range from 50 to 500 m,and minimum fill thicknesses range from 3 to 7 m.The combined channel-fill for stacked channels is up to 25 m thick.Lateral correlation of channel elements over at least 1 km of section indicates that rapid and extensive lateral migration has occurred.Crevasse splay lobes can be identified in the overbank deposits,with a width of 30e60 m and sand thickness of 0.5e1.5 m.The geometry,nature and dimensions of these architectural elements provide a useful analogue for subsurface reservoirs.The high-energy channel facies of the Quaternary system show very good reservoir attributes,with good correlation and connectivity.At the bed-scale there is significant heterogeneity of characteristics that would impact fluid-flow for hydrocarbon production from a subsurface reservoir.However,incomplete preservation of these Quaternary fluvial deposits at outcrop remains a challenge for accurately determining the scale of sedimentary features and also the size of the paleo-river.
文摘Natural open fractures(NOFs)in reservoir rocks are critical factors influencing permeability.Identifying these fractures and fractured zones typically involves analyzing core samples and image logs.However,core data are limited topecific depths within the reservoir,and image log data are confined to a small number of wells.In this study,fracture facies in a carbonate reservoir(Kangan-Dalan Formation)were predicted using Formation Micro-Imager(FMl)logs,conventional well logs,and petrophysical parameters,with a machine learning algorithm.Initially,open fractures were identified in wells A and B using the FMl log.In well A,the open fractures exhibit an average dip of 61,an azimuth of N79E,and a strike direction of N11W/S11E.In well B,the fractures have an average dip of 69°,an azimuth of N26E,and a strike direction of N64W/S64E.Subsequently,fracture density logs for wells A and B were calculated,with average values of O.41and 0.33,respectively.Conventional well logs,including density(RHOB),sonic(DT),and petrophysical parameters,specifically effective porosity(PHIE),were used as input data for a Multi-Resolution Graph-Based Clustering(MRGC)algorithm,which is one of the machine learning algorithms employed in this study.Additionally,a synthetic log called FLAG,derived from the fracture density log(with values of 0 and 1 indicating the presence or absence of fractures),was incorporated into the algorithm as an associated input log.This algorithm enabled the identification of fracture facies,representing open fractures or fractured zones,in well A.To evaluate the accuracy of the algorithm,the results obtained were compared with two other clustering algorithms:Ascendant Hierarchical Clustering(AHC)and Self-Organizing Maps(SOM).Well B was used as a blind test to validate the clustering model.In this test,the clustering algorithm was applied excluding the FLAG synthetic log derived from the FMI log.The results from well B demonstrated that the developed algorithm accurately identifies fracture facies in wells lacking image log and core data.The algorithm was subsequently extended to wells C and D,which lacked core or image log data.Fractured zones in these wells were successfully identified as fracture facies.Additionally,a two-dimensional map of fracture facies thickness was generated for the study area.The developed hybrid algorithm demonstrated strong potential for generalizing to other wells in the field,enabling fracture facies modeling in both 2D and 3D.
文摘Since long ago, indirect study of the underground layers properties has been interesting to geologists.One method for this study was seismography which gained great interest besides other tools due to thedifferent identity of waves and energy attraction phenomena in different layers. Vertical seismic profiling(VSP) is considered as a valuable method in oil and gas exploration. This method is used to estimate therock properties in a well. In seismic operations elastic waves are sent down to the underground. Part ofthe waves’ energy is reflected after passing through the earth layers and are received by receivers on theground level. The received data determine the situation of the underneath layers after being processed,and one of the most important applications of seismic data is in the oil and gas exploration field. Qualityfactor is one of the most important seismic detectors that shows itself apparently in VSP data results. Themost substantial purpose of this study is to investigate the frequency content of the quality factor.
