Hepatitis E virus(HEV)is hyperendemic in South Asia and Africa accounting for half of total Global HEV burden.There are eight genotypes of HEV.Among them,the four common ones known to infect humans,genotypes 1 and 2 a...Hepatitis E virus(HEV)is hyperendemic in South Asia and Africa accounting for half of total Global HEV burden.There are eight genotypes of HEV.Among them,the four common ones known to infect humans,genotypes 1 and 2 are prevalent in the developing world and genotypes 3 and 4 are causing challenge in the industrialized world.Asymptomatic HEV viremia in the general population,especially among blood donors,has been reported in the literature worldwide.The clinical implications related to this asymptomatic viremia are unclear and need further exploration.Detection of viremia due to HEV genotype 1 infection,apparently among healthy blood donors is also reported without much knowledge about its infection rate.Similarly,while HEV genotype 3 is known to be transmitted via blood transfusion in humans and has been subjected to screening in many European nations,instances of transmission have also been documented albeit without significant clinical consequences.Epidemiology of HEV genotype 1 in endemic areas often show waxing and waning pattern.Occasional sporadic occurrence of HEV infection interrupted by outbreaks have been frequently seen.In absence of known animal reservoir,where HEV exists in between outbreak is a mystery that needs further exploration.However,occurrence of asymptomatic HEV viremia due to HEV genotype 1 during epidemiologically quiescent period may explain that this phenomenon may act as a dynamic reservoir.Since HEV genotype 1 infection cannot cause chronicity,subclinical transient infection and transmission of virus might be the reason it sustains in interepidemic period.This might be the similar phenomenon with SARS COVID-19 corona virus infection which is circulating worldwide in distinct phases with peaks and plateaus despite vaccination against it.In view of existing evidence,we propose the concept of“Dynamic Human Reservoir.”Quiescent subclinical infection of HEV without any clinical consequences and subsequent transmission may contribute to the existence of the virus in a community.The potential for transmitting HEV infection by asymptomatic HEV infected individuals by fecal shedding of virus has not been reported in literature.This missing link may be a key to Pandora's box in understanding epidemiology of HEV infection in genotype 1 predominant region.展开更多
Since the impoundment of the Three Gorges Reservoir in 2003, algal blooms have frequently been observed in it. The chlorophyll a concentration is an important parameter for evaluating algal blooms. In this study, the ...Since the impoundment of the Three Gorges Reservoir in 2003, algal blooms have frequently been observed in it. The chlorophyll a concentration is an important parameter for evaluating algal blooms. In this study, the chlorophyll a concentration in Xiangxi Bay, in the Three Gorges Reservoir, was predicted using HJ-1 satellite imagery. Several models were established based on a correlation analysis between in situ measurements of the chlorophyll a concentration and the values obtained from satellite images of the study area from January 2010 to December 2011. Chlorophyll a concentrations in Xiangxi Bay were predicted based on the established models. The results show that the maximum correlation is between the reflectance of the band combination of B4/（B2＋B3） and in situ measurements of chlorophyll a concentration. The root mean square errors of the predicted values using the linear and quadratic models are 18.49 mg/m3 and 18.52 mg/m3, respectively, and the average relative errors are 37.79% and 36.79%, respectively. The results provide a reference for water bloom prediction in typical tributaries of the Three Gorges Reservoir and contribute to large-scale remote sensing monitoring and water quality management.展开更多
The Shahejie Formation is a fundamental rock unit for hydrocarbon exploration and production in the Nanpu Sag,Bohai Bay Basin.Methodology including thin sectioning,core observations,fluorescence,scanning electron micr...The Shahejie Formation is a fundamental rock unit for hydrocarbon exploration and production in the Nanpu Sag,Bohai Bay Basin.Methodology including thin sectioning,core observations,fluorescence,scanning electron microscopy,cathodoluminescence,fluid inclusion,laser scanning confocal microscopy and geochemical analysis(C,O isotopes)were all utilized to investigate the reservoir characteristics and origin of the Es_(1)Sandstone.Thin section study showed that the reservoir rock consisted of feldspathic litharenite and lithic arkose.The reservoir pores are categorized as intergranular pores,fracture pores,dissolution pores and intergranular cement dissolution pores.The studied sandstone had good porosity(0.05%–35%)and permeability(0.006–7000 mD).The Es_(1) reservoir is classified as a fractured reservoir,a primary intergranular pore-associated reservoir and a dissolution reservoir.Deposition,diagenesis and tectogenesis are the main factors that played important roles in the development of the reservoir.Sedimentation is the foundation and assumption for reservoir development,but the effective reservoir is primarily controlled by primary pores,fractures,lithofacies,tectonic elements and dissolution pores.Moreover,compaction,fracture filling and cementation were the primary sources of reservoir densification.The reservoir was progressively formed through the influence of different geological and diagenetic events.The present study provides significant information and references for hydrocarbon exploration and development in the Nanpu Sag.展开更多
Characteristics of Chang 21 low permeability sandstone reservoir of Shunning oil field are analyzed and evaluated based on the data of well logging and experiment. The result shows that 1) the Chang 21 low permeabilit...Characteristics of Chang 21 low permeability sandstone reservoir of Shunning oil field are analyzed and evaluated based on the data of well logging and experiment. The result shows that 1) the Chang 21 low permeability reservoir belongs to the classification of middle-to-fine sized feldspar sandstone, with its components being low in ma- turity, deposited in distributary rivers in the front of the delta; 2) the reservoir is obviously dominated by a low or a very low permeability with a linear variation tendency different from that of the ultra-low permeability reservoir; 3) the spa- tial variation in lithology and physical properties of the reservoir are controlled by the sedimentary facies zones, and 4) the physical property of the reservoir is significantly influenced by clastic constituents and their structure, and the con- stituent of cement materials and their content. The result also shows that the diagenesis action of the reservoir is quite strong in which dissolution greatly modified the reservoir In addition, the inter-granular dissolved pores are the mainly developed ones and the micro-structure is dominated by the combination of middle-to-large sized pores with fine-to-coarse throats. Finally, the radius of the throats is in good exponential correlation with permeability and the seepage capacity comes from those large sized throats.展开更多
Three-dimensional geological modeling of reservoirs is an essential tool to predict reservoir performance and improve the understanding of reservoir uniqueness in Es1 formation. The paper focuses on the use of petrel ...Three-dimensional geological modeling of reservoirs is an essential tool to predict reservoir performance and improve the understanding of reservoir uniqueness in Es1 formation. The paper focuses on the use of petrel software to build three-dimensional reservoir geological model which characterizes and assesses block Nv32 that located in the west of the Shenvsi oilfield in the south of Cangzhou city, Hebei province of China, and has an oil-bearing area of 1.4 km<sup>2</sup>. This study is depending on integration data from well logs of 22 wells which provided from geology, geophysics, and petrophysics to identify and provide precise depict of the subsurface internal structure and the reservoir heterogeneity. Input data was used to build the structural model, sedimentary facies model, petrophysical properties (porosity, permeability, saturation, and N/G model, and finally to determine the reservoir volume. The lithological facies were simulated using the assigned value method. Moreover, Petrophysical properties (Porosity, permeability, oil saturation and net to gross) were constructed for each zone using the Sequential Gaussian Simulation method to guide the distribution of petrophysical properties of Es1 formation, block Nv32. Statistical analysis of the porosity, permeability, oil saturation and N/G model present that the porosity occurrence distribution is mainly concern between 0.2% - 36.39% of block Nv32 with an average porosity value of 17.5%, permeability between 0.017 mD to 974.8 mD, having an average permeability of 59.44 mD, oil saturation between 0.00 to 0.95 having an average value of 0.22, and N/G is mainly concentrated between 0.01 to 1.00 within an average value of 0.61. This research has indicated the reliability of the three-dimensional model technique as a suitable tool to provide a sufficient understanding of petrophysical distribution. The south-western and north-western indicate that oilfield is very promising an exploratory well should be drilled to find out the thickness and size of the reservoir.展开更多
Currently,limited studies of immiscible water-alternating-CO_(2)(imWACO_(2))flooding focus on the impact of reservoir heterogeneity on reservoir development outcomes.Given this,using the heterogeneous reservoirs in th...Currently,limited studies of immiscible water-alternating-CO_(2)(imWACO_(2))flooding focus on the impact of reservoir heterogeneity on reservoir development outcomes.Given this,using the heterogeneous reservoirs in the Gao 89-1 block as a case study,this study conducted slab core flooding experiments and numerical simulations to assess the impact of reservoir heterogeneity on imWACO_(2)flooding efficiency.It can be concluded that imWACO_(2)flooding can enhance the sweep volume and oil recovery compared to continuous CO_(2)flooding.As the permeability difference increases,the difference in the swept volume between zones/layers with relatively high and low permeability increases.To optimize the exploitation of reservoirs in the Gao 89-1 block,the optimal timing and CO_(2)injection rate for imWACO_(2)flooding are determined at water cut of 40%and 10000 m^(3)/d,respectively.A short injection-production semi-period,combined with multiple cycles of water and CO_(2)injection alternations,is beneficial for enhanced oil recovery from imWACO_(2)flooding.展开更多
文摘Hepatitis E virus(HEV)is hyperendemic in South Asia and Africa accounting for half of total Global HEV burden.There are eight genotypes of HEV.Among them,the four common ones known to infect humans,genotypes 1 and 2 are prevalent in the developing world and genotypes 3 and 4 are causing challenge in the industrialized world.Asymptomatic HEV viremia in the general population,especially among blood donors,has been reported in the literature worldwide.The clinical implications related to this asymptomatic viremia are unclear and need further exploration.Detection of viremia due to HEV genotype 1 infection,apparently among healthy blood donors is also reported without much knowledge about its infection rate.Similarly,while HEV genotype 3 is known to be transmitted via blood transfusion in humans and has been subjected to screening in many European nations,instances of transmission have also been documented albeit without significant clinical consequences.Epidemiology of HEV genotype 1 in endemic areas often show waxing and waning pattern.Occasional sporadic occurrence of HEV infection interrupted by outbreaks have been frequently seen.In absence of known animal reservoir,where HEV exists in between outbreak is a mystery that needs further exploration.However,occurrence of asymptomatic HEV viremia due to HEV genotype 1 during epidemiologically quiescent period may explain that this phenomenon may act as a dynamic reservoir.Since HEV genotype 1 infection cannot cause chronicity,subclinical transient infection and transmission of virus might be the reason it sustains in interepidemic period.This might be the similar phenomenon with SARS COVID-19 corona virus infection which is circulating worldwide in distinct phases with peaks and plateaus despite vaccination against it.In view of existing evidence,we propose the concept of“Dynamic Human Reservoir.”Quiescent subclinical infection of HEV without any clinical consequences and subsequent transmission may contribute to the existence of the virus in a community.The potential for transmitting HEV infection by asymptomatic HEV infected individuals by fecal shedding of virus has not been reported in literature.This missing link may be a key to Pandora's box in understanding epidemiology of HEV infection in genotype 1 predominant region.
基金supported by the National Natural Science Foundation of China(Grants No.51009080 and 51179095)the Research Innovation Fund for Postgraduates in China Three Gorges University(Grant No.2012CX012)
文摘Since the impoundment of the Three Gorges Reservoir in 2003, algal blooms have frequently been observed in it. The chlorophyll a concentration is an important parameter for evaluating algal blooms. In this study, the chlorophyll a concentration in Xiangxi Bay, in the Three Gorges Reservoir, was predicted using HJ-1 satellite imagery. Several models were established based on a correlation analysis between in situ measurements of the chlorophyll a concentration and the values obtained from satellite images of the study area from January 2010 to December 2011. Chlorophyll a concentrations in Xiangxi Bay were predicted based on the established models. The results show that the maximum correlation is between the reflectance of the band combination of B4/（B2＋B3） and in situ measurements of chlorophyll a concentration. The root mean square errors of the predicted values using the linear and quadratic models are 18.49 mg/m3 and 18.52 mg/m3, respectively, and the average relative errors are 37.79% and 36.79%, respectively. The results provide a reference for water bloom prediction in typical tributaries of the Three Gorges Reservoir and contribute to large-scale remote sensing monitoring and water quality management.
基金This study was funded by the Natural Science Foundation of China Project(No.41602138)National Science and Technology Special Grant(No.2016ZX05006-007)+1 种基金China Postdoctoral Science Foundation-funded project(No.2015M580617,2017T100524)the Fundamental Research Funds for the Central Universities(No.15CX08001A).
文摘The Shahejie Formation is a fundamental rock unit for hydrocarbon exploration and production in the Nanpu Sag,Bohai Bay Basin.Methodology including thin sectioning,core observations,fluorescence,scanning electron microscopy,cathodoluminescence,fluid inclusion,laser scanning confocal microscopy and geochemical analysis(C,O isotopes)were all utilized to investigate the reservoir characteristics and origin of the Es_(1)Sandstone.Thin section study showed that the reservoir rock consisted of feldspathic litharenite and lithic arkose.The reservoir pores are categorized as intergranular pores,fracture pores,dissolution pores and intergranular cement dissolution pores.The studied sandstone had good porosity(0.05%–35%)and permeability(0.006–7000 mD).The Es_(1) reservoir is classified as a fractured reservoir,a primary intergranular pore-associated reservoir and a dissolution reservoir.Deposition,diagenesis and tectogenesis are the main factors that played important roles in the development of the reservoir.Sedimentation is the foundation and assumption for reservoir development,but the effective reservoir is primarily controlled by primary pores,fractures,lithofacies,tectonic elements and dissolution pores.Moreover,compaction,fracture filling and cementation were the primary sources of reservoir densification.The reservoir was progressively formed through the influence of different geological and diagenetic events.The present study provides significant information and references for hydrocarbon exploration and development in the Nanpu Sag.
文摘Characteristics of Chang 21 low permeability sandstone reservoir of Shunning oil field are analyzed and evaluated based on the data of well logging and experiment. The result shows that 1) the Chang 21 low permeability reservoir belongs to the classification of middle-to-fine sized feldspar sandstone, with its components being low in ma- turity, deposited in distributary rivers in the front of the delta; 2) the reservoir is obviously dominated by a low or a very low permeability with a linear variation tendency different from that of the ultra-low permeability reservoir; 3) the spa- tial variation in lithology and physical properties of the reservoir are controlled by the sedimentary facies zones, and 4) the physical property of the reservoir is significantly influenced by clastic constituents and their structure, and the con- stituent of cement materials and their content. The result also shows that the diagenesis action of the reservoir is quite strong in which dissolution greatly modified the reservoir In addition, the inter-granular dissolved pores are the mainly developed ones and the micro-structure is dominated by the combination of middle-to-large sized pores with fine-to-coarse throats. Finally, the radius of the throats is in good exponential correlation with permeability and the seepage capacity comes from those large sized throats.
文摘Three-dimensional geological modeling of reservoirs is an essential tool to predict reservoir performance and improve the understanding of reservoir uniqueness in Es1 formation. The paper focuses on the use of petrel software to build three-dimensional reservoir geological model which characterizes and assesses block Nv32 that located in the west of the Shenvsi oilfield in the south of Cangzhou city, Hebei province of China, and has an oil-bearing area of 1.4 km<sup>2</sup>. This study is depending on integration data from well logs of 22 wells which provided from geology, geophysics, and petrophysics to identify and provide precise depict of the subsurface internal structure and the reservoir heterogeneity. Input data was used to build the structural model, sedimentary facies model, petrophysical properties (porosity, permeability, saturation, and N/G model, and finally to determine the reservoir volume. The lithological facies were simulated using the assigned value method. Moreover, Petrophysical properties (Porosity, permeability, oil saturation and net to gross) were constructed for each zone using the Sequential Gaussian Simulation method to guide the distribution of petrophysical properties of Es1 formation, block Nv32. Statistical analysis of the porosity, permeability, oil saturation and N/G model present that the porosity occurrence distribution is mainly concern between 0.2% - 36.39% of block Nv32 with an average porosity value of 17.5%, permeability between 0.017 mD to 974.8 mD, having an average permeability of 59.44 mD, oil saturation between 0.00 to 0.95 having an average value of 0.22, and N/G is mainly concentrated between 0.01 to 1.00 within an average value of 0.61. This research has indicated the reliability of the three-dimensional model technique as a suitable tool to provide a sufficient understanding of petrophysical distribution. The south-western and north-western indicate that oilfield is very promising an exploratory well should be drilled to find out the thickness and size of the reservoir.
基金funded by the National Natural Science Foundation of China(No.51974343)the Open Fund of Hubei Key Laboratory of Drilling and Production Engineering for Oil and Gas(Yangtze University)(No.YQZC202307)+2 种基金the Qingdao Postdoctoral Applied Research Project(No.qdyy20200084)the China Postdoctoral Science Foundation(No.2021M703588)a project of Science&Technology R&D Department of SINOPEC entitled Key Technology for Optimization Design of 3D Development of Shale oil in Dongying Sag(No.P23026).
文摘Currently,limited studies of immiscible water-alternating-CO_(2)(imWACO_(2))flooding focus on the impact of reservoir heterogeneity on reservoir development outcomes.Given this,using the heterogeneous reservoirs in the Gao 89-1 block as a case study,this study conducted slab core flooding experiments and numerical simulations to assess the impact of reservoir heterogeneity on imWACO_(2)flooding efficiency.It can be concluded that imWACO_(2)flooding can enhance the sweep volume and oil recovery compared to continuous CO_(2)flooding.As the permeability difference increases,the difference in the swept volume between zones/layers with relatively high and low permeability increases.To optimize the exploitation of reservoirs in the Gao 89-1 block,the optimal timing and CO_(2)injection rate for imWACO_(2)flooding are determined at water cut of 40%and 10000 m^(3)/d,respectively.A short injection-production semi-period,combined with multiple cycles of water and CO_(2)injection alternations,is beneficial for enhanced oil recovery from imWACO_(2)flooding.
