Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,a...Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,and reservoir characteristics of shale oil of fine-grained sediment deposition in continental freshwater lacustrine basins,with a focus on the Chang 7_(3) sub-member of Triassic Yanchang Formation.The research integrates a variety of exploration data,including field outcrops,drilling,logging,core samples,geochemical analyses,and flume simulation.The study indicates that:(1)The paleoenvironment of the Chang 7_(3) deposition is characterized by a warm and humid climate,frequent monsoon events,and a large water depth of freshwater lacustrine basin.The paleogeomorphology exhibits an asymmetrical pattern,with steep slopes in the southwest and gentle slopes in the northeast,which can be subdivided into microgeomorphological units,including depressions and ridges in lakebed,as well as ancient channels.(2)The Chang 7_(3) sub-member is characterized by a diverse array of fine-grained sediments,including very fine sandstone,siltstone,mudstone and tuff.These sediments are primarily distributed in thin interbedded and laminated arrangements vertically.The overall grain size of the sandstone predominantly falls below 62.5μm,with individual layer thicknesses of 0.05–0.64 m.The deposits contain intact plant fragments and display various sedimentary structure,such as wavy bedding,inverse-to-normal grading sequence,and climbing ripple bedding,which indicating a depositional origin associated with density flows.(3)Flume simulation experiments have successfully replicated the transport processes and sedimentary characteristics associated with density flows.The initial phase is characterized by a density-velocity differential,resulting in a thicker,coarser sediment layer at the flow front,while the upper layers are thinner and finer in grain size.During the mid-phase,sliding water effects cause the fluid front to rise and facilitate rapid forward transport.This process generates multiple“new fronts”,enabling the long-distance transport of fine-grained sandstones,such as siltstone and argillaceous siltstone,into the center of the lake basin.(4)A sedimentary model primarily controlled by hyperpynal flows was established for the southwestern part of the basin,highlighting that the frequent occurrence of flood events and the steep slope topography in this area are primary controlling factors for the development of hyperpynal flows.(5)Sandstone and mudstone in the Chang 7_(3) sub-member exhibit micro-and nano-scale pore-throat systems,shale oil is present in various lithologies,while the content of movable oil varies considerably,with sandstone exhibiting the highest content of movable oil.(6)The fine-grained sediment complexes formed by multiple episodes of sandstones and mudstones associated with density flow in the Chang 7_(3) formation exhibit characteristics of“overall oil-bearing with differential storage capacity”.The combination of mudstone with low total organic carbon content(TOC)and siltstone is identified as the most favorable exploration target at present.展开更多
Sedimentation in reservoirs is a significant challenge that affects water storage capacity and operational efficiency.This study establishes a baseline sedimentation status for Mwimba Reservoir in Kasungu,Malawi,five ...Sedimentation in reservoirs is a significant challenge that affects water storage capacity and operational efficiency.This study establishes a baseline sedimentation status for Mwimba Reservoir in Kasungu,Malawi,five years after its commissioning in 2017,using an integrated bathymetric survey and Geographic Information System(GIS)analysis.A bathymetric survey conducted in March 2022 collected depth measurements at 507 points along 23 transects,which were used to construct a Triangulated Irregular Network(TIN)model in ArcGIS for accurate volume calculations.Sediment concentration was determined from seven water samples using the filtration method.The original design volume of 89,200 m^(3)was compared to the current volume of 72,966 m^(3),indicating an 18.2% loss in capacity over the five-year period.Statistical analysis using a one-sample T-test confirmed that this reduction is significant(p=0.013).The annual sedimentation rate was estimated at 1.25 tonnes per year,and the reservoir’s projected operational life is 27.5 years if no intervention is undertaken.Despite a relatively low sedimentation rate compared to other regional reservoirs,targeted sediment management and further catchment analysis are essential.This study provides critical baseline data for future sediment monitoring,management,and conservation planning for Mwimba Reservoir and similar small water bodies in Sub-Saharan Africa.展开更多
Understanding the sedimentation and simultaneous consolidation behavior of xanthan gum(XG)-biopolymer-treated soils remains a significant research gap in developing environmentally friendly ground-improvement techniqu...Understanding the sedimentation and simultaneous consolidation behavior of xanthan gum(XG)-biopolymer-treated soils remains a significant research gap in developing environmentally friendly ground-improvement techniques for geotechnical applications.This study addresses this gap by conducting laboratory experiments on kaolinite suspensions with varying XG-to-kaolinite mass ratios(mb/ms).The results showed that the XG treatment modified the sedimentation patterns by promoting larger floc formation and accelerated settling.Additionally,the XG treatment enhanced the shear stiffness and shear strength,particularly at shallow depths.At mb/ms ratios less than 1%,the volume compression was reduced by the XG;the coefficient of compressibility decreased by 49%at 1%mb/ms,and the consolidation was accelerated,as indicated by a 387%increase in the hydraulic conductivity at 0.5%mb/ms under the vertical effective stress of 40 kPa.Contrastingly,at mb/ms ratios greater than 1%,viscous XG hydrogels clogged pores,resulting in a 45%reduction in the coefficient of consolidation at 2%mb/ms under a vertical effective stress of 15 kPa and a 35%decrease in the hydraulic conductivity at 2%mb/ms under a vertical effective stress of 40 kPa.These findings underscore the potential of XG treatment in improving the sedimentation and consolidation processes,highlighting its applicability in geotechnical projects,such as dredging,landfilling,and artificial island construction.展开更多
The Zhujiang River Mouth Basin,a primary depocenter for terrigenous sediments in the western Pacific,presents a semienclosed tectonic setting with limited exchange with the open ocean.This unique feature enables syste...The Zhujiang River Mouth Basin,a primary depocenter for terrigenous sediments in the western Pacific,presents a semienclosed tectonic setting with limited exchange with the open ocean.This unique feature enables systematic linkages among sedimentary processes,climate change,regional sea-level fluctuations,and tectonic events.To explore these linkages,this study focuses on Well PY35 in the Baiyun Sag of the Zhujiang River Mouth Basin.By integrating microfossil analysis with Milankovitch cycle analysis of well log data,an astronomical time scale(ATS)(17.54-7.80 Ma)and a high-resolution stratigraphic framework were established,allowing for the calculation of sedimentation rates across different hierarchical sequences and time intervals.The results indicate that between 17.54 Ma and 7.80 Ma,the sedimentation rate initially increased and then decreased,ranging from 6.1 cm/ka to 45.7 cm/ka,with an average rate of 22.2 cm/ka.During the Middle Miocene Climatic Optimum(MMCO),sedimentation rates were moderate and exhibited an increasing trend,largely driven by increased sediment input due to enhanced weathering from rising temperatures and by expanded accommodation space resulting from tectonic subsidence.Meanwhile,the Middle Miocene Climate Transition(MMCT)was marked by a notable rise in sedimentation rates,consistent with a major sea-level fall due to global cooling,which promoted the direct seaward progradation of marginal sediments.The Late Middle Miocene to Late Miocene had the lowest sedimentation rates,which can be attributed to reduced weathering under cold and arid conditions,along with a sea-level rise induced by regional tectonics.The short-term increase in the sedimentation rate observed at 10.4 Ma may have been driven by sea-level fluctuations.This study provides both theoretical and empirical support for understanding the influence of abrupt climate changes on sedimentary processes.展开更多
Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficult...Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficulties associated with managing SSW sludge.This study comprehensively evaluated the water quality of SSW by comparing it to a well-documented wastewater(filter backwash water(FBW)).Furthermore,it investigated the pollutant variations in the SSW during pre-sedimentation process,probed the underlying reaction mechanism,and explored the feasibility of employing a pilot-scale coagulation-sedimentation process for SSW treatment.The levels of most water quality parameters were generally comparable between SSW and FBW.During the pre-sedimentation of SSW,significant removal of turbidity,bacterial counts,and dissolved organic matter(DOM)was observed.The characterization of DOM components,molecular weight distributions,and optical properties revealed that the macromolecular proteinaceous biopolymers and humic acids were preferentially removed.The characterization of particulates indicated that high surface energy,zeta potential,and bridging/adsorption/sedimentation/coagulation capacities in aluminum residuals of SSW,underscoring its potential as a coagulant and promoting the generation and sedimentation of inorganic-organic complexes.The coagulation-sedimentation process could effectively remove pollutants from low-turbidity SSW([turbidity]0<15 NTU).These findings provide valuable insights into the water quality dynamics of SSW during the pre-sedimentation process,facilitating the development of SSW quality management and enhancing its reuse rate.展开更多
This study focuses on tuffaceous clastic rocks of the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin.It aims to explore the influence of sedimentation and parent rock on this kind of res...This study focuses on tuffaceous clastic rocks of the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin.It aims to explore the influence of sedimentation and parent rock on this kind of reservoir development.The results show that the tuffaceous components formed by the denudation of ultramafic and mafic rocks can transform into chlorite coating or hematite,while those from intermediate rock denudation can be dissolved or transformed into illite.Sedimentary facies and lithofacies are essential in controlling the evolutionary result of tuffaceous components.Matrix-supported medium conglomerate and grain-supported medium-fine conglomerate that developed in the fan delta plain,with a closed original geochemical systems,have been in the oxidizing environment for a long time.The tuffaceous matrices mainly transforms into hematite or illite.These minerals occupy the primary pores and are difficult to dissolve by felsic fluids,which inhibits the development of high-quality reservoirs.The grain-supported sandy fine conglomerate developed in the fan delta front was in the underwater reductive environment with an open original geochemical system.The tuffaceous matrices not only can transform into chlorite coating to strengthen the particle's compaction resistance,but also can be fully dissolved,which promotes the formation of high-quality reservoirs.展开更多
In order to accelerate the sedimentation of super-large-scale argillized ultrafine tailings with bad features such as low settling velocity, muddy overflow water, and large flocculant dosage, a fly-ash-based magnetic ...In order to accelerate the sedimentation of super-large-scale argillized ultrafine tailings with bad features such as low settling velocity, muddy overflow water, and large flocculant dosage, a fly-ash-based magnetic coagulant （FAMC） was used in a dynamic experimental device. To obtain the best possible combination of the impact factors （magnetic intensity, FAMC dosage, flocculant dosage, and feed speed） for minimum overflow turbidity, a response surface methodology test coupled with a four-factor five-level central composite design was conducted. The synergy mechanism of FAMC and flocculant was analyzed based on the potential measurement and scanning electron microscopy. The results show that the flocculant dosage, overflow turbidity, and solid content can be reduced by 50%, 90%, and 80%, while the handling capacity per unit and efficiency of backfill and dry stacking can be promoted by 20%, 17%, and 13%, respectively, with a magnetic intensity of 0.3 T, FAMC dosage of 200 mL/t, flocculant dosage of 30 g/t, and feed speed of 0.6 t/（m^2·h）. Therefore, synergy of FAMC and flocculant has obvious efficiency in saving energy and protecting the environment by allowing 70×10^6 t/a of argillized ultrafine tailings slurry to be disposed safely and efficiently with a cost saving of more than 53×106 Yuan/a, which gives it great promise for use in domestic and foreign mines.展开更多
基金Supported by the CNPC Major Science and Technology Project(2021DJ1806).
文摘Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,and reservoir characteristics of shale oil of fine-grained sediment deposition in continental freshwater lacustrine basins,with a focus on the Chang 7_(3) sub-member of Triassic Yanchang Formation.The research integrates a variety of exploration data,including field outcrops,drilling,logging,core samples,geochemical analyses,and flume simulation.The study indicates that:(1)The paleoenvironment of the Chang 7_(3) deposition is characterized by a warm and humid climate,frequent monsoon events,and a large water depth of freshwater lacustrine basin.The paleogeomorphology exhibits an asymmetrical pattern,with steep slopes in the southwest and gentle slopes in the northeast,which can be subdivided into microgeomorphological units,including depressions and ridges in lakebed,as well as ancient channels.(2)The Chang 7_(3) sub-member is characterized by a diverse array of fine-grained sediments,including very fine sandstone,siltstone,mudstone and tuff.These sediments are primarily distributed in thin interbedded and laminated arrangements vertically.The overall grain size of the sandstone predominantly falls below 62.5μm,with individual layer thicknesses of 0.05–0.64 m.The deposits contain intact plant fragments and display various sedimentary structure,such as wavy bedding,inverse-to-normal grading sequence,and climbing ripple bedding,which indicating a depositional origin associated with density flows.(3)Flume simulation experiments have successfully replicated the transport processes and sedimentary characteristics associated with density flows.The initial phase is characterized by a density-velocity differential,resulting in a thicker,coarser sediment layer at the flow front,while the upper layers are thinner and finer in grain size.During the mid-phase,sliding water effects cause the fluid front to rise and facilitate rapid forward transport.This process generates multiple“new fronts”,enabling the long-distance transport of fine-grained sandstones,such as siltstone and argillaceous siltstone,into the center of the lake basin.(4)A sedimentary model primarily controlled by hyperpynal flows was established for the southwestern part of the basin,highlighting that the frequent occurrence of flood events and the steep slope topography in this area are primary controlling factors for the development of hyperpynal flows.(5)Sandstone and mudstone in the Chang 7_(3) sub-member exhibit micro-and nano-scale pore-throat systems,shale oil is present in various lithologies,while the content of movable oil varies considerably,with sandstone exhibiting the highest content of movable oil.(6)The fine-grained sediment complexes formed by multiple episodes of sandstones and mudstones associated with density flow in the Chang 7_(3) formation exhibit characteristics of“overall oil-bearing with differential storage capacity”.The combination of mudstone with low total organic carbon content(TOC)and siltstone is identified as the most favorable exploration target at present.
基金the Agricultural Research and Extension Trust of Malawi and the Centre of Excellence of Transformative Agriculture Commercialisation at Lilongwe University of Agriculture and Natural Resources for supporting this study.
文摘Sedimentation in reservoirs is a significant challenge that affects water storage capacity and operational efficiency.This study establishes a baseline sedimentation status for Mwimba Reservoir in Kasungu,Malawi,five years after its commissioning in 2017,using an integrated bathymetric survey and Geographic Information System(GIS)analysis.A bathymetric survey conducted in March 2022 collected depth measurements at 507 points along 23 transects,which were used to construct a Triangulated Irregular Network(TIN)model in ArcGIS for accurate volume calculations.Sediment concentration was determined from seven water samples using the filtration method.The original design volume of 89,200 m^(3)was compared to the current volume of 72,966 m^(3),indicating an 18.2% loss in capacity over the five-year period.Statistical analysis using a one-sample T-test confirmed that this reduction is significant(p=0.013).The annual sedimentation rate was estimated at 1.25 tonnes per year,and the reservoir’s projected operational life is 27.5 years if no intervention is undertaken.Despite a relatively low sedimentation rate compared to other regional reservoirs,targeted sediment management and further catchment analysis are essential.This study provides critical baseline data for future sediment monitoring,management,and conservation planning for Mwimba Reservoir and similar small water bodies in Sub-Saharan Africa.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(Grant No.2022R1A2C2091517).
文摘Understanding the sedimentation and simultaneous consolidation behavior of xanthan gum(XG)-biopolymer-treated soils remains a significant research gap in developing environmentally friendly ground-improvement techniques for geotechnical applications.This study addresses this gap by conducting laboratory experiments on kaolinite suspensions with varying XG-to-kaolinite mass ratios(mb/ms).The results showed that the XG treatment modified the sedimentation patterns by promoting larger floc formation and accelerated settling.Additionally,the XG treatment enhanced the shear stiffness and shear strength,particularly at shallow depths.At mb/ms ratios less than 1%,the volume compression was reduced by the XG;the coefficient of compressibility decreased by 49%at 1%mb/ms,and the consolidation was accelerated,as indicated by a 387%increase in the hydraulic conductivity at 0.5%mb/ms under the vertical effective stress of 40 kPa.Contrastingly,at mb/ms ratios greater than 1%,viscous XG hydrogels clogged pores,resulting in a 45%reduction in the coefficient of consolidation at 2%mb/ms under a vertical effective stress of 15 kPa and a 35%decrease in the hydraulic conductivity at 2%mb/ms under a vertical effective stress of 40 kPa.These findings underscore the potential of XG treatment in improving the sedimentation and consolidation processes,highlighting its applicability in geotechnical projects,such as dredging,landfilling,and artificial island construction.
基金The National Natural Science Foundation of China under contract Nos 42372170,42472055,42272177,and 42077410the Safety Discipline“double first-class”to found Project of China under contract No.AQ20240305.
文摘The Zhujiang River Mouth Basin,a primary depocenter for terrigenous sediments in the western Pacific,presents a semienclosed tectonic setting with limited exchange with the open ocean.This unique feature enables systematic linkages among sedimentary processes,climate change,regional sea-level fluctuations,and tectonic events.To explore these linkages,this study focuses on Well PY35 in the Baiyun Sag of the Zhujiang River Mouth Basin.By integrating microfossil analysis with Milankovitch cycle analysis of well log data,an astronomical time scale(ATS)(17.54-7.80 Ma)and a high-resolution stratigraphic framework were established,allowing for the calculation of sedimentation rates across different hierarchical sequences and time intervals.The results indicate that between 17.54 Ma and 7.80 Ma,the sedimentation rate initially increased and then decreased,ranging from 6.1 cm/ka to 45.7 cm/ka,with an average rate of 22.2 cm/ka.During the Middle Miocene Climatic Optimum(MMCO),sedimentation rates were moderate and exhibited an increasing trend,largely driven by increased sediment input due to enhanced weathering from rising temperatures and by expanded accommodation space resulting from tectonic subsidence.Meanwhile,the Middle Miocene Climate Transition(MMCT)was marked by a notable rise in sedimentation rates,consistent with a major sea-level fall due to global cooling,which promoted the direct seaward progradation of marginal sediments.The Late Middle Miocene to Late Miocene had the lowest sedimentation rates,which can be attributed to reduced weathering under cold and arid conditions,along with a sea-level rise induced by regional tectonics.The short-term increase in the sedimentation rate observed at 10.4 Ma may have been driven by sea-level fluctuations.This study provides both theoretical and empirical support for understanding the influence of abrupt climate changes on sedimentary processes.
基金supported by the Ministry of Science and Technology of China (Nos.2021YFC3200904,and 2022YFC3203705)the National Natural Science Foundation of China (Nos.52070184,and 52270012)the Nanning Scientific Research and Technology Development Project (No.ZC20223238).
文摘Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficulties associated with managing SSW sludge.This study comprehensively evaluated the water quality of SSW by comparing it to a well-documented wastewater(filter backwash water(FBW)).Furthermore,it investigated the pollutant variations in the SSW during pre-sedimentation process,probed the underlying reaction mechanism,and explored the feasibility of employing a pilot-scale coagulation-sedimentation process for SSW treatment.The levels of most water quality parameters were generally comparable between SSW and FBW.During the pre-sedimentation of SSW,significant removal of turbidity,bacterial counts,and dissolved organic matter(DOM)was observed.The characterization of DOM components,molecular weight distributions,and optical properties revealed that the macromolecular proteinaceous biopolymers and humic acids were preferentially removed.The characterization of particulates indicated that high surface energy,zeta potential,and bridging/adsorption/sedimentation/coagulation capacities in aluminum residuals of SSW,underscoring its potential as a coagulant and promoting the generation and sedimentation of inorganic-organic complexes.The coagulation-sedimentation process could effectively remove pollutants from low-turbidity SSW([turbidity]0<15 NTU).These findings provide valuable insights into the water quality dynamics of SSW during the pre-sedimentation process,facilitating the development of SSW quality management and enhancing its reuse rate.
基金supported by the National Natural Science Foundation of China(Grant Nos.42172109,41872113,42172108)China National Petroleum Corporation-China University of Petroleum(Beijing)Strategic Cooperation Science and Technology Project(Grant No.ZLZX2020-02)+1 种基金State's Key Project of Research and Development Plan(Grant No.2018YFA0702405)Science Foundation of China University of Petroleum(Beijing)(Grant Nos.2462020BJRC002,2462020YXZZ020)。
文摘This study focuses on tuffaceous clastic rocks of the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin.It aims to explore the influence of sedimentation and parent rock on this kind of reservoir development.The results show that the tuffaceous components formed by the denudation of ultramafic and mafic rocks can transform into chlorite coating or hematite,while those from intermediate rock denudation can be dissolved or transformed into illite.Sedimentary facies and lithofacies are essential in controlling the evolutionary result of tuffaceous components.Matrix-supported medium conglomerate and grain-supported medium-fine conglomerate that developed in the fan delta plain,with a closed original geochemical systems,have been in the oxidizing environment for a long time.The tuffaceous matrices mainly transforms into hematite or illite.These minerals occupy the primary pores and are difficult to dissolve by felsic fluids,which inhibits the development of high-quality reservoirs.The grain-supported sandy fine conglomerate developed in the fan delta front was in the underwater reductive environment with an open original geochemical system.The tuffaceous matrices not only can transform into chlorite coating to strengthen the particle's compaction resistance,but also can be fully dissolved,which promotes the formation of high-quality reservoirs.
基金Project(2012BAC09B02)supported by the 12th-Five Years Key Programs for Science and Technology Development of ChinaProject(2015zzts078)supported by the Fundamental Research Funds for the Central Universities of Central South University,ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China
文摘In order to accelerate the sedimentation of super-large-scale argillized ultrafine tailings with bad features such as low settling velocity, muddy overflow water, and large flocculant dosage, a fly-ash-based magnetic coagulant （FAMC） was used in a dynamic experimental device. To obtain the best possible combination of the impact factors （magnetic intensity, FAMC dosage, flocculant dosage, and feed speed） for minimum overflow turbidity, a response surface methodology test coupled with a four-factor five-level central composite design was conducted. The synergy mechanism of FAMC and flocculant was analyzed based on the potential measurement and scanning electron microscopy. The results show that the flocculant dosage, overflow turbidity, and solid content can be reduced by 50%, 90%, and 80%, while the handling capacity per unit and efficiency of backfill and dry stacking can be promoted by 20%, 17%, and 13%, respectively, with a magnetic intensity of 0.3 T, FAMC dosage of 200 mL/t, flocculant dosage of 30 g/t, and feed speed of 0.6 t/（m^2·h）. Therefore, synergy of FAMC and flocculant has obvious efficiency in saving energy and protecting the environment by allowing 70×10^6 t/a of argillized ultrafine tailings slurry to be disposed safely and efficiently with a cost saving of more than 53×106 Yuan/a, which gives it great promise for use in domestic and foreign mines.
