Natural gas hydrates,intricate crystalline structures formed by water molecules and small gas molecules,have emerged as a significant and globally impactful clean energy resource.However,their commercial exploitation ...Natural gas hydrates,intricate crystalline structures formed by water molecules and small gas molecules,have emerged as a significant and globally impactful clean energy resource.However,their commercial exploitation faces challenges,particularly operational disruptions caused by sand-related blockages.Understanding the rheological properties of hydrate slurry,especially in the presence of micron-sized sand particles,is imperative for ensuring the flow assurance of subsea hydrate exploitation.This study extensively investigates the rheological properties of sand-containing hydrate slurries.The findings reveal that these slurries exhibit non-Newtonian fluid characteristics,including yield stress,thixotropy,and shear-thinning behavior.Solid-like elastic features are observed in sand-containing hydrate slurries before yielding,transitioning to viscous behavior after yielding.Even with a minimal amount of sand,both static yield stress and yield strain experience substantial changes,correlating with the increase in sand concentration.The research conclusively establishes the thixotropic nature of sand-hydrate slurries,where the viscosity decay rate is directly influenced by the shear rate.These insights aim to contribute comprehensively to the development of effective flow assurance strategies,ensuring the safe and stable operation of subsea hydrate exploitation.展开更多
Seafloor topography plays an important role in the evolution of submarine lobes.However,it is still not so clear how the shape of slope affects the three-dimensional(3-D)architecture of submarine lobes.In this study,w...Seafloor topography plays an important role in the evolution of submarine lobes.However,it is still not so clear how the shape of slope affects the three-dimensional(3-D)architecture of submarine lobes.In this study,we analyze the effect of topography factors on different hierarchical lobe architectures that formed during Pliocene to Quaternary in the Rovuma Basin offshore East Africa.We characterize the shape,size and growth pattern of different hierarchical lobe architectures using 3-D seismic data.We find that the relief of the topographic slope determines the location of preferential deposition of lobe complexes and single lobes.When the topography is irregular and presents topographic lows,lobe complexes first infill these depressions.Single lobes are deposited preferentially at positions with higher longitudinal(i.e.across-slope)slope gradients.As the longitudinal slope becomes higher,the aspect ratio of the single lobes increases.Lateral(i.e.along-slope)topography does not seem to have a strong influence on the shape of single lobe,but it seems to affect the overlap of single lobes.When the lateral slope gradient is relatively high,the single lobes tend to have a larger overlap surface.Furthermore,as the average of lateral slope and longitudinal slope gets greater,the width/thickness ratio of the single lobe is smaller,i.e.sediments tend to accumulate vertically.The results demonstrate that the shape of slopes more comprehensively influences the 3-D architecture of lobes in natural deep-sea systems than previously other lobe deposits and analogue experiments,which helps us better understand the development and evolution of the distal parts of turbidite systems.展开更多
浮式液化天然气(FLNG)生产储卸装置近年来取得了显著发展,目前,全球有5个FLNG项目建成在产,分别是Prelude FLNG、PFLNG Satu FLNG、PFLNG DUA FLNG、Hilli Episeyo FLNG、Coral Sul FLNG。这些项目在澳大利亚、马来西亚、喀麦隆、莫桑...浮式液化天然气(FLNG)生产储卸装置近年来取得了显著发展,目前,全球有5个FLNG项目建成在产,分别是Prelude FLNG、PFLNG Satu FLNG、PFLNG DUA FLNG、Hilli Episeyo FLNG、Coral Sul FLNG。这些项目在澳大利亚、马来西亚、喀麦隆、莫桑比克海域服役,参与企业有壳牌、马来西亚国家石油公司、埃尼、中国石油等。Gimi FLNG、Tango FLNG、Brazzaville FLNG、Perenco FLNG是正在建设的4个项目,其中既有世界首个开发跨国界气藏的项目,也有建设历程最波折复杂的项目,还有由其他船型改造而成的项目。全球有5个待建的FLNG项目,分别是UTM FLNG、Leviathan FLNG、Delfin FLNG、Golar FLNG、Cedar FLNG。FLNG项目面临着技术需要长周期运行检验、可能存在环保问题和资源国反对等挑战。尽管如此,FLNG项目仍然具有巨大的发展潜力。中国是世界最大的LNG进口国,中国企业应在FLNG技术攻关、工程建设管理能力提升和资源整合方面加大投入力度。展开更多
Carbon politics is quietly emerging,and countries around the world are divided into three categories.Western developed countries consuming clean energy are classified as the first category.Energy-importing developing ...Carbon politics is quietly emerging,and countries around the world are divided into three categories.Western developed countries consuming clean energy are classified as the first category.Energy-importing developing countries are included in the second category,and resource-rich countries relying on fossil fuel export are sorted as the third category.Countries of the“three categories”have already and will continue to play games over“dual carbon”round after round.The goal of Western countries’carbon politics is to continue to lead the world,stay ahead,and use their advantage of low emission to extract carbon benefits.Energy-importing developing countries face threats and opportunities.Resource-rich countries are unable to tackle the situation without aggravating another problem.China should narrow its gap in the new energy industry with Western developed countries,continue to promote natural gas pipeline construction to ensure energy security,control the pace to realize the“dual carbon”goal,and strive for its own legitimate rights and interests.展开更多
基金supported by the National Natural Science Foundation of China(52104069,U20B6005)Beijing Municipal Natural Science Foundation(3232030)Science Foundation of China University of Petroleum,Beijing(2462023BJRC018,2462020YXZZ045).
文摘Natural gas hydrates,intricate crystalline structures formed by water molecules and small gas molecules,have emerged as a significant and globally impactful clean energy resource.However,their commercial exploitation faces challenges,particularly operational disruptions caused by sand-related blockages.Understanding the rheological properties of hydrate slurry,especially in the presence of micron-sized sand particles,is imperative for ensuring the flow assurance of subsea hydrate exploitation.This study extensively investigates the rheological properties of sand-containing hydrate slurries.The findings reveal that these slurries exhibit non-Newtonian fluid characteristics,including yield stress,thixotropy,and shear-thinning behavior.Solid-like elastic features are observed in sand-containing hydrate slurries before yielding,transitioning to viscous behavior after yielding.Even with a minimal amount of sand,both static yield stress and yield strain experience substantial changes,correlating with the increase in sand concentration.The research conclusively establishes the thixotropic nature of sand-hydrate slurries,where the viscosity decay rate is directly influenced by the shear rate.These insights aim to contribute comprehensively to the development of effective flow assurance strategies,ensuring the safe and stable operation of subsea hydrate exploitation.
基金The study is funded by the Cooperation Project of China National Petroleum Company(CNPC)and China University of Petroleum-Beijing(CUPB)(No.RIPED-2021-JS-552)the National Natural Science Foundation of China(Nos.42002112,42272110)+2 种基金the Strategic Cooperation Technology Projects of CNPC and CUPB(No.ZLZX2020-02)the Science Foundation for Youth Scholars of CUPB(No.24620222BJRC006)We thank the China Scholarship Council(CSC)(No.202106440048)for having funded the research stay of Mei Chen at MARUM,University of Bremen.We thank Elda Miramontes for her constructive comments and suggestions that helped us improve our manuscript.
文摘Seafloor topography plays an important role in the evolution of submarine lobes.However,it is still not so clear how the shape of slope affects the three-dimensional(3-D)architecture of submarine lobes.In this study,we analyze the effect of topography factors on different hierarchical lobe architectures that formed during Pliocene to Quaternary in the Rovuma Basin offshore East Africa.We characterize the shape,size and growth pattern of different hierarchical lobe architectures using 3-D seismic data.We find that the relief of the topographic slope determines the location of preferential deposition of lobe complexes and single lobes.When the topography is irregular and presents topographic lows,lobe complexes first infill these depressions.Single lobes are deposited preferentially at positions with higher longitudinal(i.e.across-slope)slope gradients.As the longitudinal slope becomes higher,the aspect ratio of the single lobes increases.Lateral(i.e.along-slope)topography does not seem to have a strong influence on the shape of single lobe,but it seems to affect the overlap of single lobes.When the lateral slope gradient is relatively high,the single lobes tend to have a larger overlap surface.Furthermore,as the average of lateral slope and longitudinal slope gets greater,the width/thickness ratio of the single lobe is smaller,i.e.sediments tend to accumulate vertically.The results demonstrate that the shape of slopes more comprehensively influences the 3-D architecture of lobes in natural deep-sea systems than previously other lobe deposits and analogue experiments,which helps us better understand the development and evolution of the distal parts of turbidite systems.
文摘Carbon politics is quietly emerging,and countries around the world are divided into three categories.Western developed countries consuming clean energy are classified as the first category.Energy-importing developing countries are included in the second category,and resource-rich countries relying on fossil fuel export are sorted as the third category.Countries of the“three categories”have already and will continue to play games over“dual carbon”round after round.The goal of Western countries’carbon politics is to continue to lead the world,stay ahead,and use their advantage of low emission to extract carbon benefits.Energy-importing developing countries face threats and opportunities.Resource-rich countries are unable to tackle the situation without aggravating another problem.China should narrow its gap in the new energy industry with Western developed countries,continue to promote natural gas pipeline construction to ensure energy security,control the pace to realize the“dual carbon”goal,and strive for its own legitimate rights and interests.
