This study presents a thorough and holistic review of various studies focusing on the structural analysis of Oil and Gas(O&G)pipelines,with an emphasis on various defect modes.The study appraised pipeline-related ...This study presents a thorough and holistic review of various studies focusing on the structural analysis of Oil and Gas(O&G)pipelines,with an emphasis on various defect modes.The study appraised pipeline-related articles from the empirical,semi-empirical,analytical,and numerical studies.However,the study’s core objective remains to address the persistent challenge that often leads to Burst Pressure Loss(BPL)in a pipeline.These mechanical-associated damages,which can result in BPL,may include pipe scratches,dents,or cracks.Therefore,training a large volume of datasets in neural network architectures or the finite element domain is crucial in this context.The study further explores previous research to gain a deeper insight into how many modes of damage enhance loss in Burst Pressure(BP).The study further synthesises significant reasons why pipeline Structural Health Failures(SHFs)occur,as drawn from existing literature.Failure scenarios in pipeline dent,crack,fracture,buckling,fatigue,corrosion,BPL,and Third-Party Damage(TPD)could result from mechanical deformation,ageing,insufficient real-time monitoring,and TPD influences.Many of the assessed articles conclude that the experimental approach and Finite Element Method(FEM)are valid and can accurately validate one another in the analysis and prediction of pipeline failures.However,this study offers valuable and comprehensive resources for pipeline engineers,academic researchers,and industry professionals.Again,the study is crucial for pipeline fabricators,installers,and operators to keep up with maintenance,repairs,and predictions.展开更多
A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs.This temperature-preserved core chamber employs...A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs.This temperature-preserved core chamber employs an innovative vacuum layer for temperature preservation and is compatible with a temperature-pressure preserved coring system.The design principles and key parameters of the temperature-preserved core chamber were determined through static analysis.Numerical simulations assessed the mechanical properties of 70,85,and 100 MPa core chambers under conditions of 120-150℃.The results demonstrate that the temperature-preserved core chambers withstand the applied stresses without plastic deformation,and the vacuum layer maintains its integrity under these conditions.A 70 MPa class core chamber prototype was manufactured,and system integration tests were performed on a self-developed in-situ coring platform.The system demonstrated stable operation at 70 MPa for 120 min,with pressure fluctuations within 5%.Additionally,the integrated system operated without interference,enabling the successful extraction of cores with a 50 mm diameter.These findings provide valuable theoretical guidance and design recommendations for advancing oil and gas in-situ temperature-pressure preserved coring technologies in high-temperature and high-pressure environments.展开更多
This paper presents a novel approach to model and simulate the multi-support depth-varying seismic motions（MDSMs） within heterogeneous offshore and onshore sites.Based on 1 D wave propagation theory,the three-dimens...This paper presents a novel approach to model and simulate the multi-support depth-varying seismic motions（MDSMs） within heterogeneous offshore and onshore sites.Based on 1 D wave propagation theory,the three-dimensional ground motion transfer functions on the surface or within an offshore or onshore site are derived by considering the effects of seawater and porous soils on the propagation of seismic P waves.Moreover,the depth-varying and spatial variation properties of seismic ground motions are considered in the ground motion simulation.Using the obtained transfer functions at any locations within a site,the offshore or onshore depth-varying seismic motions are stochastically simulated based on the spectral representation method（SRM）.The traditional approaches for simulating spatially varying ground motions are improved and extended to generate MDSMs within multiple offshore and onshore sites.The simulation results show that the PSD functions and coherency losses of the generated MDSMs are compatible with respective target values,which fully validates the effectiveness of the proposed simulation method.The synthesized MDSMs can provide strong support for the precise seismic response prediction and performance-based design of both offshore and onshore large-span engineering structures.展开更多
A winter onshore warm tongue extending from the Yellow Sea Warm Current to the southern Jiangsu coast, and an of fshore cold tongue extending from the southern Jiangsu coast to the southwest of Jeju Island(South Korea...A winter onshore warm tongue extending from the Yellow Sea Warm Current to the southern Jiangsu coast, and an of fshore cold tongue extending from the southern Jiangsu coast to the southwest of Jeju Island(South Korea), are newly identified based on the sea-surface temperature from satellite remote sensing, and further confirmed by the distribution of suspended sediments. In addition, there are two obvious thermal fronts associated with the onshore warm tongue and off shore cold tongue. The narrow gap between the two thermal fronts is supposed to be the pathway for the off shore transport of cold coastal water and suspended sediments. The concurrence of onshore warm and of fshore cold tongues suggests the concurrence of onshore and off shore currents in the western Yellow Sea in winter, which seems to be inconsistent with the previously accepted view that, in winter, the Yellow Sea Coastal Current flows from the Old Huanghe Delta to the southwest of Jeju Island. This distinctive phenomenon helps establish an updated view of the circulation in the western Yellow Sea in winter.展开更多
In-situ conversion processing (ICP) of shale oil underground at the depth ranging from 300 m to 3 000 m is a physical and chemical process caused by using horizontal drilling and electric heating technology, which con...In-situ conversion processing (ICP) of shale oil underground at the depth ranging from 300 m to 3 000 m is a physical and chemical process caused by using horizontal drilling and electric heating technology, which converts heavy oil, bitumen and various organic matter into light oil and gas in a large scale, which can be called"underground refinery". ICP has several advantages as in CO2capture, recoverable resource potential and the quality of hydrocarbon output. Based on the geothermal evolution mechanism of organic materials established by Tissot et al., this study reveals that in the nonmarine organic-rich shale sequence, the amount of liquid hydrocarbon maintaining in the shale is as high as 25%in the liquid hydrocarbon window stage (R o less than 1.0%), and the unconverted organic materials (low mature-immature organic materials) in the shale interval can reach 40%to 100%. The conditions of organic-rich shale suitable for underground in-situ conversion of shale oil should be satisfied in the following aspects, TOC higher than 6%, R o ranging between 0.5%and 1%, concentrated thickness of organic-rich shale greater than 15 meters, burial depth less than 3 000 m, covering area bigger than 50 km2, good sealing condition in both up-and down-contacting sequences and water content smaller than 5%, etc. The shale oil resource in China’s onshore region is huge. It is estimated with this paper that the technical recoverable resource reaches 70-90 billion tons of oil and 60-65 trillion cubic meters of gas. The ICP of shale oil underground is believed to be a fairway to find big oil in the source kitchen in the near future. And it is also believed to be a milestone to keep China long-term stability of oil and gas sufficient supply by putting ICP of shale oil underground into real practice in the future.展开更多
Deep marine carbonate rocks have become one of the key targets of onshore oil and gas exploration and development for reserves replacement in China.Further geological researches of such rocks may practically facilitat...Deep marine carbonate rocks have become one of the key targets of onshore oil and gas exploration and development for reserves replacement in China.Further geological researches of such rocks may practically facilitate the sustainable,steady and smooth development of the petroleum industry in the country.Therefore,through a deep investigation into the fundamental geological conditions of deep marine carbonate reservoirs,we found higher-than-expected resource potential therein,which may uncover large oil or gas fields.The findings were reflected in four aspects.Firstly,there are two kinds of hydrocarbon kitchens which were respectively formed by conventional source rocks and liquid hydrocarbons cracking that were detained in source rocks,and both of them can provide large-scale hydrocarbons.Secondly,as controlled by the bedding and interstratal karstification,as well as the burial and hydrothermal dolomitization,effective carbonate reservoirs may be extensively developed in the deep and ultra-deep strata.Thirdly,under the coupling action of progressive burial and annealing heating,some marine source rocks could form hydrocarbon accumulations spanning important tectonic phases,and large quantity of liquid hydrocarbons could be kept in late stage,contributing to rich oil and gas in such deep marine strata.Fourthly,large-scale uplifts were formed by the stacking of multi-episodic tectonism and oil and gas could be accumulated in three modes(i.e.,stratoid large-area reservoir-forming mode of karst reservoirs in the slope area of uplift,back-flow type large-area reservoir-forming mode of buried hill weathered crust karst reservoirs,and wide-range reservoir-forming mode of reef-shoal reservoirs);groups of stratigraphic and lithologic traps were widely developed in the areas of periclinal structures of paleohighs and continental margins.In conclusion,deep marine carbonate strata in China onshore contain the conditions for widely and intensively preserving hydrocarbons,so large oil or gas fields are expected.展开更多
The inland lakes on the Tibetan Plateau are inhabited by diverse microbial communities,which play a significant role in biogeochemical cycles of biogenic elements(e.g.carbon,nitrogen).Onshore inputs provide essential
China's onshore petroleum in-dustry has achieved sat-isfactory results in its economic and technical cooperation with foreign countries as it 1S acce-lerating its economic reform and opening w1der to the outside w...China's onshore petroleum in-dustry has achieved sat-isfactory results in its economic and technical cooperation with foreign countries as it 1S acce-lerating its economic reform and opening w1der to the outside world.展开更多
The bidding blocks are distributed in different regions of China,There are seven blocks in W est China,and seven blocks in Northeast China,the other twelve blocks are from North and Central China.All the blocks are lo...The bidding blocks are distributed in different regions of China,There are seven blocks in W est China,and seven blocks in Northeast China,the other twelve blocks are from North and Central China.All the blocks are located in prospective sedimentary basins with different geological condi-tions,some are from oil produced basin such as Bohai Bay Basin which is a prolific basin,it's production accounts for 50%in total prodcuction of China.Based on estimation,the total potential resource of oil is 3.55 billion tons and gas is 800 billion cubic meters in bidding areas.As far as the exploratory objectives are concerned,there are Paleozoic.Mesozoic and Cenozoic strata,as well as continental clastic and marine一carbonate re-servoir.These provide more choices for foreign companies.In addition,most of bidding blocks are adjacent to transport lines,so communication and petroleum transportation are very convenient.展开更多
In this research the investigated parameters are given as below: The History of offshore and onshore construction is given where onshore structures as storage tanks and breakwaters with Estacada are mentioned with hie...In this research the investigated parameters are given as below: The History of offshore and onshore construction is given where onshore structures as storage tanks and breakwaters with Estacada are mentioned with hierarchical steps. To the offshore structures belong stationary fixed platforms (steel, concrete, combined, arctic) with floating (Jack-up, semi-submersibles, TLP,…) and pipe line construction. This issues are given as State-of-the-art and written as new examined innovative researches.展开更多
This study examines transient overvoltage phenomena in 525 kV high-voltage direct current(HVDC)onshore cable systems,with particular emphasis on the influence of grounding configurations in two joint types:straight-th...This study examines transient overvoltage phenomena in 525 kV high-voltage direct current(HVDC)onshore cable systems,with particular emphasis on the influence of grounding configurations in two joint types:straight-through and screen-separated.Transient overvoltages arising from wave propagation and reflections are analysed,highlighting the impact of joint types,bonding cable configurations(coaxial vs.noncoaxial)and bonding cable length on the resulting overvoltage magnitudes.The necessity of modelling screen-to-earth representations of sectionalised cables at grounded joint locations in the vicinity of faults is emphasised,whereas simplified representations of ungrounded and grounded straight-through joints are identified as sufficient for system-level simulations.To address the computational challenges of detailed electromagnetic transient simulations,a stand-alone simplified circuit is proposed to analyse grounded joint transients and to mitigate errors caused by insufficient time-step resolution.The results provide practical insights for insulation coordination,supporting the reliable integration of HVDC technology into long-distance cable-based transmission networks while enhancing system resilience.展开更多
Understanding the characteristics of the dynamic relationship between the onshore Ren- minbi （CNY） and the offshore Renminbi （CNH） exchange rates considering the impact of some extreme events is very important and...Understanding the characteristics of the dynamic relationship between the onshore Ren- minbi （CNY） and the offshore Renminbi （CNH） exchange rates considering the impact of some extreme events is very important and it has wide implications in several areas such as hedging. For better esti- mating the dynamic relationship between CNY and CNH, the Granger-causality test and Bry-Boschan Business Cycle Dating Algorithm were employed in this paper. Due to the intrinsic complexity of the lead-lag relationships between CNY and CNH, the empirical mode decomposition （EMD） algorithm is used to decompose those time series data into several intrinsic mode function （IMF） components and a residual sequence, from high to low frequency. Based on the frequencies, the IMFs and a residual sequence are combined into three components, identified as short-term composition caused by some market activities, medium-term composition caused by some extreme events and the long-term trend.The empirical results indicate that when it only matters the short-term market activities, CNH always leads CNY; while the medium-term impact caused by those extreme events may alternate the lead-lag relationships between CNY and CNH.展开更多
文摘This study presents a thorough and holistic review of various studies focusing on the structural analysis of Oil and Gas(O&G)pipelines,with an emphasis on various defect modes.The study appraised pipeline-related articles from the empirical,semi-empirical,analytical,and numerical studies.However,the study’s core objective remains to address the persistent challenge that often leads to Burst Pressure Loss(BPL)in a pipeline.These mechanical-associated damages,which can result in BPL,may include pipe scratches,dents,or cracks.Therefore,training a large volume of datasets in neural network architectures or the finite element domain is crucial in this context.The study further explores previous research to gain a deeper insight into how many modes of damage enhance loss in Burst Pressure(BP).The study further synthesises significant reasons why pipeline Structural Health Failures(SHFs)occur,as drawn from existing literature.Failure scenarios in pipeline dent,crack,fracture,buckling,fatigue,corrosion,BPL,and Third-Party Damage(TPD)could result from mechanical deformation,ageing,insufficient real-time monitoring,and TPD influences.Many of the assessed articles conclude that the experimental approach and Finite Element Method(FEM)are valid and can accurately validate one another in the analysis and prediction of pipeline failures.However,this study offers valuable and comprehensive resources for pipeline engineers,academic researchers,and industry professionals.Again,the study is crucial for pipeline fabricators,installers,and operators to keep up with maintenance,repairs,and predictions.
基金the financial support from the National Key R&D Program of China(No.2022YFB3706604)the National Natural Science Foundation of China(52304033)+2 种基金the National Natural Science Foundation of China(No.51827901)Sichuan Science and Technology Program(2023NSFSC0790)China Postdoctoral Science Foundation(No.2023M742446)。
文摘A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs.This temperature-preserved core chamber employs an innovative vacuum layer for temperature preservation and is compatible with a temperature-pressure preserved coring system.The design principles and key parameters of the temperature-preserved core chamber were determined through static analysis.Numerical simulations assessed the mechanical properties of 70,85,and 100 MPa core chambers under conditions of 120-150℃.The results demonstrate that the temperature-preserved core chambers withstand the applied stresses without plastic deformation,and the vacuum layer maintains its integrity under these conditions.A 70 MPa class core chamber prototype was manufactured,and system integration tests were performed on a self-developed in-situ coring platform.The system demonstrated stable operation at 70 MPa for 120 min,with pressure fluctuations within 5%.Additionally,the integrated system operated without interference,enabling the successful extraction of cores with a 50 mm diameter.These findings provide valuable theoretical guidance and design recommendations for advancing oil and gas in-situ temperature-pressure preserved coring technologies in high-temperature and high-pressure environments.
基金National Key R&D Program of China under Grant No.2016YFC0701108the State Key Program of National Natural Science Foundation of China under Grant No.51738007
文摘This paper presents a novel approach to model and simulate the multi-support depth-varying seismic motions（MDSMs） within heterogeneous offshore and onshore sites.Based on 1 D wave propagation theory,the three-dimensional ground motion transfer functions on the surface or within an offshore or onshore site are derived by considering the effects of seawater and porous soils on the propagation of seismic P waves.Moreover,the depth-varying and spatial variation properties of seismic ground motions are considered in the ground motion simulation.Using the obtained transfer functions at any locations within a site,the offshore or onshore depth-varying seismic motions are stochastically simulated based on the spectral representation method（SRM）.The traditional approaches for simulating spatially varying ground motions are improved and extended to generate MDSMs within multiple offshore and onshore sites.The simulation results show that the PSD functions and coherency losses of the generated MDSMs are compatible with respective target values,which fully validates the effectiveness of the proposed simulation method.The synthesized MDSMs can provide strong support for the precise seismic response prediction and performance-based design of both offshore and onshore large-span engineering structures.
基金Supported by the Strategy Program of Chinese Academy of Sciences(Nos.XDA10020104,XDA10020305)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.41421005)+2 种基金the National Natural Science Foundation of China(Nos.41476019,41606040)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406401)the High Performance Computing Center,Institute of Oceanology,Chinese Academy of Sciences in Qingdao
文摘A winter onshore warm tongue extending from the Yellow Sea Warm Current to the southern Jiangsu coast, and an of fshore cold tongue extending from the southern Jiangsu coast to the southwest of Jeju Island(South Korea), are newly identified based on the sea-surface temperature from satellite remote sensing, and further confirmed by the distribution of suspended sediments. In addition, there are two obvious thermal fronts associated with the onshore warm tongue and off shore cold tongue. The narrow gap between the two thermal fronts is supposed to be the pathway for the off shore transport of cold coastal water and suspended sediments. The concurrence of onshore warm and of fshore cold tongues suggests the concurrence of onshore and off shore currents in the western Yellow Sea in winter, which seems to be inconsistent with the previously accepted view that, in winter, the Yellow Sea Coastal Current flows from the Old Huanghe Delta to the southwest of Jeju Island. This distinctive phenomenon helps establish an updated view of the circulation in the western Yellow Sea in winter.
基金Supported by the International Cooperation Project of China National Petroleum Corporation(2015D-4810-02)China National Science and Technology Major Project(2016ZX05046)
文摘In-situ conversion processing (ICP) of shale oil underground at the depth ranging from 300 m to 3 000 m is a physical and chemical process caused by using horizontal drilling and electric heating technology, which converts heavy oil, bitumen and various organic matter into light oil and gas in a large scale, which can be called"underground refinery". ICP has several advantages as in CO2capture, recoverable resource potential and the quality of hydrocarbon output. Based on the geothermal evolution mechanism of organic materials established by Tissot et al., this study reveals that in the nonmarine organic-rich shale sequence, the amount of liquid hydrocarbon maintaining in the shale is as high as 25%in the liquid hydrocarbon window stage (R o less than 1.0%), and the unconverted organic materials (low mature-immature organic materials) in the shale interval can reach 40%to 100%. The conditions of organic-rich shale suitable for underground in-situ conversion of shale oil should be satisfied in the following aspects, TOC higher than 6%, R o ranging between 0.5%and 1%, concentrated thickness of organic-rich shale greater than 15 meters, burial depth less than 3 000 m, covering area bigger than 50 km2, good sealing condition in both up-and down-contacting sequences and water content smaller than 5%, etc. The shale oil resource in China’s onshore region is huge. It is estimated with this paper that the technical recoverable resource reaches 70-90 billion tons of oil and 60-65 trillion cubic meters of gas. The ICP of shale oil underground is believed to be a fairway to find big oil in the source kitchen in the near future. And it is also believed to be a milestone to keep China long-term stability of oil and gas sufficient supply by putting ICP of shale oil underground into real practice in the future.
基金Special and Significant Project of National Science and Technology“Development of Large Oil/gas Fields and Coalbed Methane”(No.2011ZX05004-001).
文摘Deep marine carbonate rocks have become one of the key targets of onshore oil and gas exploration and development for reserves replacement in China.Further geological researches of such rocks may practically facilitate the sustainable,steady and smooth development of the petroleum industry in the country.Therefore,through a deep investigation into the fundamental geological conditions of deep marine carbonate reservoirs,we found higher-than-expected resource potential therein,which may uncover large oil or gas fields.The findings were reflected in four aspects.Firstly,there are two kinds of hydrocarbon kitchens which were respectively formed by conventional source rocks and liquid hydrocarbons cracking that were detained in source rocks,and both of them can provide large-scale hydrocarbons.Secondly,as controlled by the bedding and interstratal karstification,as well as the burial and hydrothermal dolomitization,effective carbonate reservoirs may be extensively developed in the deep and ultra-deep strata.Thirdly,under the coupling action of progressive burial and annealing heating,some marine source rocks could form hydrocarbon accumulations spanning important tectonic phases,and large quantity of liquid hydrocarbons could be kept in late stage,contributing to rich oil and gas in such deep marine strata.Fourthly,large-scale uplifts were formed by the stacking of multi-episodic tectonism and oil and gas could be accumulated in three modes(i.e.,stratoid large-area reservoir-forming mode of karst reservoirs in the slope area of uplift,back-flow type large-area reservoir-forming mode of buried hill weathered crust karst reservoirs,and wide-range reservoir-forming mode of reef-shoal reservoirs);groups of stratigraphic and lithologic traps were widely developed in the areas of periclinal structures of paleohighs and continental margins.In conclusion,deep marine carbonate strata in China onshore contain the conditions for widely and intensively preserving hydrocarbons,so large oil or gas fields are expected.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41030211 and 41002123)the Scientific Research Funds for the 1000 "Talents" Program Plan from China University of Geosciences (Beijing)+1 种基金State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (No. GBL11201)the Fundamental Research Funds for National University, China University of Geosciences (Wuhan)
文摘The inland lakes on the Tibetan Plateau are inhabited by diverse microbial communities,which play a significant role in biogeochemical cycles of biogenic elements(e.g.carbon,nitrogen).Onshore inputs provide essential
文摘China's onshore petroleum in-dustry has achieved sat-isfactory results in its economic and technical cooperation with foreign countries as it 1S acce-lerating its economic reform and opening w1der to the outside world.
文摘The bidding blocks are distributed in different regions of China,There are seven blocks in W est China,and seven blocks in Northeast China,the other twelve blocks are from North and Central China.All the blocks are located in prospective sedimentary basins with different geological condi-tions,some are from oil produced basin such as Bohai Bay Basin which is a prolific basin,it's production accounts for 50%in total prodcuction of China.Based on estimation,the total potential resource of oil is 3.55 billion tons and gas is 800 billion cubic meters in bidding areas.As far as the exploratory objectives are concerned,there are Paleozoic.Mesozoic and Cenozoic strata,as well as continental clastic and marine一carbonate re-servoir.These provide more choices for foreign companies.In addition,most of bidding blocks are adjacent to transport lines,so communication and petroleum transportation are very convenient.
文摘In this research the investigated parameters are given as below: The History of offshore and onshore construction is given where onshore structures as storage tanks and breakwaters with Estacada are mentioned with hierarchical steps. To the offshore structures belong stationary fixed platforms (steel, concrete, combined, arctic) with floating (Jack-up, semi-submersibles, TLP,…) and pipe line construction. This issues are given as State-of-the-art and written as new examined innovative researches.
文摘This study examines transient overvoltage phenomena in 525 kV high-voltage direct current(HVDC)onshore cable systems,with particular emphasis on the influence of grounding configurations in two joint types:straight-through and screen-separated.Transient overvoltages arising from wave propagation and reflections are analysed,highlighting the impact of joint types,bonding cable configurations(coaxial vs.noncoaxial)and bonding cable length on the resulting overvoltage magnitudes.The necessity of modelling screen-to-earth representations of sectionalised cables at grounded joint locations in the vicinity of faults is emphasised,whereas simplified representations of ungrounded and grounded straight-through joints are identified as sufficient for system-level simulations.To address the computational challenges of detailed electromagnetic transient simulations,a stand-alone simplified circuit is proposed to analyse grounded joint transients and to mitigate errors caused by insufficient time-step resolution.The results provide practical insights for insulation coordination,supporting the reliable integration of HVDC technology into long-distance cable-based transmission networks while enhancing system resilience.
基金National Program on Key Basic Research Project (973 Program) (No. 2001CB209100)Doctoral Research Fund of Beijing University of Technology (52104001200701)
基金partially supported by the National Natural Science Foundation of China under Grant Nos.71390330,71390331,71390335the National Nature Science Foundation of China for financial support to this study+1 种基金supported by the Postdoctorate Programme of Centre University of Economics and Financethe Postodctorate Programme of China Great Wall Asset Management Corporation
文摘Understanding the characteristics of the dynamic relationship between the onshore Ren- minbi （CNY） and the offshore Renminbi （CNH） exchange rates considering the impact of some extreme events is very important and it has wide implications in several areas such as hedging. For better esti- mating the dynamic relationship between CNY and CNH, the Granger-causality test and Bry-Boschan Business Cycle Dating Algorithm were employed in this paper. Due to the intrinsic complexity of the lead-lag relationships between CNY and CNH, the empirical mode decomposition （EMD） algorithm is used to decompose those time series data into several intrinsic mode function （IMF） components and a residual sequence, from high to low frequency. Based on the frequencies, the IMFs and a residual sequence are combined into three components, identified as short-term composition caused by some market activities, medium-term composition caused by some extreme events and the long-term trend.The empirical results indicate that when it only matters the short-term market activities, CNH always leads CNY; while the medium-term impact caused by those extreme events may alternate the lead-lag relationships between CNY and CNH.
