The Upper Permian Gohan Formation,a terrestrial stratum deposited in the foreland basin in central eastern Korea,provides information on the provenance,tectonic setting,and paleoclimatic conditions of the eastern marg...The Upper Permian Gohan Formation,a terrestrial stratum deposited in the foreland basin in central eastern Korea,provides information on the provenance,tectonic setting,and paleoclimatic conditions of the eastern margin of the Sino-Korean block(SKB)composed of the North China craton and the Korean Peninsula.Geochemical composition of Gohan mudrocks suggests that the source rocks consisted of a mixture of intermediate−mafic igneous rocks and some sedimentary rocks.The source terrain was situated in an Andean-type active continental margin setting.In the clay mineral composition,kaolinite predominates in the lower section,illite in the middle,and illite and chlorite in the upper section.Such upsection changes are consistent with the upward decrease of chemical weathering index,which indicates that the climatic conditions of Late Permian time changed from hot and humid to semiarid.展开更多
Conventional time-space domain and frequency-space domain prediction filtering methods assume that seismic data consists of two parts, signal and random noise. That is, the so-called additive noise model. However, whe...Conventional time-space domain and frequency-space domain prediction filtering methods assume that seismic data consists of two parts, signal and random noise. That is, the so-called additive noise model. However, when estimating random noise, it is assumed that random noise can be predicted from the seismic data by convolving with a prediction error filter. That is, the source-noise model. Model inconsistencies, before and after denoising, compromise the noise attenuation and signal-preservation performances of prediction filtering methods. Therefore, this study presents an inversion-based time-space domain random noise attenuation method to overcome the model inconsistencies. In this method, a prediction error filter （PEF）, is first estimated from seismic data; the filter characterizes the predictability of the seismic data and adaptively describes the seismic data＇s space structure. After calculating PEF, it can be applied as a regularized constraint in the inversion process for seismic signal from noisy data. Unlike conventional random noise attenuation methods, the proposed method solves a seismic data inversion problem using regularization constraint; this overcomes the model inconsistency of the prediction filtering method. The proposed method was tested on both synthetic and real seismic data, and results from the prediction filtering method and the proposed method are compared. The testing demonstrated that the proposed method suppresses noise effectively and provides better signal-preservation performance.展开更多
To describe the distribution of sandstone reservoirs between wells finely,this paper takes the sandstone reservoir of Layer Nm II-4 in Qinhuangdao 32-6 Oilfield for example,and uses the seismic forward simulation and ...To describe the distribution of sandstone reservoirs between wells finely,this paper takes the sandstone reservoir of Layer Nm II-4 in Qinhuangdao 32-6 Oilfield for example,and uses the seismic forward simulation and well loggings to study the channel sandstone reservoir. Under the guidance of the modern rivers and outcrops sandstone distribution pattern,the predicting limitations of the seismic forward simulation about channel sandstone boundaries such as mudstone interlayer between channel sandstone and elevation distance between adjacent channel sandstone are clear. The research shows that the mudstone interlayer can be described by seismic forward simulation seismic when the mudstone interlayer is thicker than 2 m and the channel sandstone is thicker than 10 m because of the appearance of the seismic peak when the main frequency of seismic data is nearly 60 Hz. And the elevation distance between adjacent channel sandstone can be described by the seismic forward simulation when elevation distance is longer than 6 m and the channel sandstone is thicker than 10 m because of the appearance of the seismic peak. And the seismic waveform features of single channel sandstone boundaries such as elevation distance between channels,overbank sandstone and abandoned channels. Under the study mentioned above,the single channel boundaries are described in Layer Nm II-4 of Qinhuangdao 32-6 Oilfield,and the predicting boundaries are confirmed by the chemical tracers. The results show that the channel sandstone reservoir architecture characterization can be improved by the seismic forward simulation.展开更多
A multi-band circular polarizer using a twisted triple split-ring resonator（TSRR） is presented and studied numerically and experimentally. At four distinct resonant frequencies, the incident linearly polarized wave ...A multi-band circular polarizer using a twisted triple split-ring resonator（TSRR） is presented and studied numerically and experimentally. At four distinct resonant frequencies, the incident linearly polarized wave can be transformed into left/right-handed circularly polarized waves. Numerical simulation results show that a y-polarized wave can be converted into a right-handed circularly polarized wave at 5.738 GHz and 9.218 GHz, while a left-handed circularly polarized wave is produced at 7.292 GHz and 10.118 GHz. The experimental results are in agreement with the numerical results. The surface current distributions are investigated to illustrate the polarization transformation mechanism. Furthermore, the influences of the structure parameters of the circular polarizer on transmission spectra are discussed as well.展开更多
The Atlantic Meridional Overturning Circulation(AMOC)serves as an important conduit for poleward heat transport in the global ocean,playing a crucial role in regulating global climate.However,biases have been found in...The Atlantic Meridional Overturning Circulation(AMOC)serves as an important conduit for poleward heat transport in the global ocean,playing a crucial role in regulating global climate.However,biases have been found in multi-model simulations of AMOC,particularly due to inaccuracies in convective mixing parameterization,which leads to an overestimation of convective mixing depth in the Labrador Sea and Nordic Seas.This excessive deep convection results in stronger simulated AMOC transport compared to observations.Therefore,this study employs the Large Eddy Simulation(LES)method to simulate the sinking process of dense water using a series of idealized experiments with various sea surface salt flux,latitude,and ocean stratification.The results show that increased salt flux forcing and weakened background stratification both enhance the sinking of dense water,with geographical location(latitude)exerting a discernable impact.Based on these insights,the eddy viscosity coefficient,which characterizes vertical convective mixing in the parameterization scheme,is refined,with adjustments to its vertical structure and the incorporation of latitude dependence.It is preliminarily applied to simulate AMOC using the Community Earth System Model(CESM).The results demonstrate improvements in the simulation accuracy of seawater temperature at the near-surface and deep layers.Including the parameterization scheme of dense water sinking in the model leads to a reduction in the simulated intensity of AMOC at 26.5°N.In the high-latitude North Atlantic,the modification implemented in parameterization results in notable improvements in the simulation of seawater temperature,salinity,and density,with respective reductions in their root mean square errors of 4.36%,19.77%,and 1.84%.展开更多
The mode-I fracture toughness is of great significance for evaluating the fracturing ability of shale reservoirs.In this study,the mode-I fracture toughness of the shale in the Lower Silurian Longmaxi Formation,Southe...The mode-I fracture toughness is of great significance for evaluating the fracturing ability of shale reservoirs.In this study,the mode-I fracture toughness of the shale in the Lower Silurian Longmaxi Formation,Southern Sichuan Basin was determined with the Cracked Chevron Notched Brazilian Disc(CCNBD).Based on the experimental data,the relationships among the mode-I fracture toughness,the density,the acoustic time and the clay mineral content were analyzed.The shale samples for fracture toughness test from cores were commonly limited,the investigation of fracture toughness using well logs was necessary.Therefore,a prediction model was proposed by correlating the fracture toughness with well logs responses.The results indicate that the fracture toughness of shale samples is from 0.4744 MPa$m1/2 to 1.0607 MPa$m1/2 with an average of 0.7817 MPa$m1/2,indicating that the anisotropy of fracture toughness of the Longmaxi Formation shale.The clay mineral content and the density have a positive effect on the fracture toughness,whereas the acoustic time plays a negative role on the fracture toughness.The clay mineral content has an important effect on the relationships among fracture toughness,acoustic time and density.The prediction model can provide continuous data of mode-I fracture toughness along the wellbore for field hydraulic fracturing operation,and it has certain guiding significance in the exploration and development of oil and gas reservoirs.展开更多
The acoustic response characteristics of shales were investigated by the acoustic transmission experiment,which is the basis of solving geological and engineering problems using the seismic or logging information duri...The acoustic response characteristics of shales were investigated by the acoustic transmission experiment,which is the basis of solving geological and engineering problems using the seismic or logging information during the process of the exploration and development of shale gas reservoirs.Based on the theory of acoustic wave and the background of acoustic transmission experiment,the initial condition,vibration source condition,boundary condition and stability condition were constructed,and the numerical simulation of acoustic transmission experiment of shales were completed through Matlab programming.The results show that under the same bedding angle,the acoustic time and attenuation coefficient of shales shown positive correlation with the bedding density;whereas under the same bedding density,the variation laws of the acoustic time and the attenuation coefficient of shales were more complex with the change of the bedding angle,that is,the acoustic time and attenuation coefficient of shales increased first,then decreased and then increased again with the increase of the bedding angle.展开更多
基金supported by the National Research Foundation of Korea(grant number 2014R1A2A2A01005404)H.Kwon acknowledges support from the SEES-BK21+Program at SNU.M.G.Kim also acknowledges support from the Korea Institute of Geoscience and Mineral Resources(GP2020-003)funded by the Ministry of Science and ICT,Korea.
文摘The Upper Permian Gohan Formation,a terrestrial stratum deposited in the foreland basin in central eastern Korea,provides information on the provenance,tectonic setting,and paleoclimatic conditions of the eastern margin of the Sino-Korean block(SKB)composed of the North China craton and the Korean Peninsula.Geochemical composition of Gohan mudrocks suggests that the source rocks consisted of a mixture of intermediate−mafic igneous rocks and some sedimentary rocks.The source terrain was situated in an Andean-type active continental margin setting.In the clay mineral composition,kaolinite predominates in the lower section,illite in the middle,and illite and chlorite in the upper section.Such upsection changes are consistent with the upward decrease of chemical weathering index,which indicates that the climatic conditions of Late Permian time changed from hot and humid to semiarid.
基金supported by the National Natural Science Foundation of China(No.41474109)the China National Petroleum Corporation under grant number 2016A-33
文摘Conventional time-space domain and frequency-space domain prediction filtering methods assume that seismic data consists of two parts, signal and random noise. That is, the so-called additive noise model. However, when estimating random noise, it is assumed that random noise can be predicted from the seismic data by convolving with a prediction error filter. That is, the source-noise model. Model inconsistencies, before and after denoising, compromise the noise attenuation and signal-preservation performances of prediction filtering methods. Therefore, this study presents an inversion-based time-space domain random noise attenuation method to overcome the model inconsistencies. In this method, a prediction error filter （PEF）, is first estimated from seismic data; the filter characterizes the predictability of the seismic data and adaptively describes the seismic data＇s space structure. After calculating PEF, it can be applied as a regularized constraint in the inversion process for seismic signal from noisy data. Unlike conventional random noise attenuation methods, the proposed method solves a seismic data inversion problem using regularization constraint; this overcomes the model inconsistency of the prediction filtering method. The proposed method was tested on both synthetic and real seismic data, and results from the prediction filtering method and the proposed method are compared. The testing demonstrated that the proposed method suppresses noise effectively and provides better signal-preservation performance.
基金supported by the China National Petroleum Corporation Major Project (No. 2011E2506)
文摘To describe the distribution of sandstone reservoirs between wells finely,this paper takes the sandstone reservoir of Layer Nm II-4 in Qinhuangdao 32-6 Oilfield for example,and uses the seismic forward simulation and well loggings to study the channel sandstone reservoir. Under the guidance of the modern rivers and outcrops sandstone distribution pattern,the predicting limitations of the seismic forward simulation about channel sandstone boundaries such as mudstone interlayer between channel sandstone and elevation distance between adjacent channel sandstone are clear. The research shows that the mudstone interlayer can be described by seismic forward simulation seismic when the mudstone interlayer is thicker than 2 m and the channel sandstone is thicker than 10 m because of the appearance of the seismic peak when the main frequency of seismic data is nearly 60 Hz. And the elevation distance between adjacent channel sandstone can be described by the seismic forward simulation when elevation distance is longer than 6 m and the channel sandstone is thicker than 10 m because of the appearance of the seismic peak. And the seismic waveform features of single channel sandstone boundaries such as elevation distance between channels,overbank sandstone and abandoned channels. Under the study mentioned above,the single channel boundaries are described in Layer Nm II-4 of Qinhuangdao 32-6 Oilfield,and the predicting boundaries are confirmed by the chemical tracers. The results show that the channel sandstone reservoir architecture characterization can be improved by the seismic forward simulation.
基金Project supported by the National Natural Science Foundation of China(Grant No.41474117)the Special Funds for Development Scientific Research Unit Projects of Wuhan,China(Grant No.2013BJ004)
文摘A multi-band circular polarizer using a twisted triple split-ring resonator（TSRR） is presented and studied numerically and experimentally. At four distinct resonant frequencies, the incident linearly polarized wave can be transformed into left/right-handed circularly polarized waves. Numerical simulation results show that a y-polarized wave can be converted into a right-handed circularly polarized wave at 5.738 GHz and 9.218 GHz, while a left-handed circularly polarized wave is produced at 7.292 GHz and 10.118 GHz. The experimental results are in agreement with the numerical results. The surface current distributions are investigated to illustrate the polarization transformation mechanism. Furthermore, the influences of the structure parameters of the circular polarizer on transmission spectra are discussed as well.
基金supported by the National Natural Science Foundation of China(No.92162103)the Natural Science Foundation of Hunan Province,China(No.2022JJ30699)+1 种基金the Science and Technology Innovation Program of Hunan Province,China(No.2021RC4055)the Open Research Project from the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(No.GPMR202112)。
基金supported by the National Natural Science Foundation of China(Grant Nos.42250710152,42192562&42406022)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_1442)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)funded project(Grant No.SML2020SP007)。
文摘The Atlantic Meridional Overturning Circulation(AMOC)serves as an important conduit for poleward heat transport in the global ocean,playing a crucial role in regulating global climate.However,biases have been found in multi-model simulations of AMOC,particularly due to inaccuracies in convective mixing parameterization,which leads to an overestimation of convective mixing depth in the Labrador Sea and Nordic Seas.This excessive deep convection results in stronger simulated AMOC transport compared to observations.Therefore,this study employs the Large Eddy Simulation(LES)method to simulate the sinking process of dense water using a series of idealized experiments with various sea surface salt flux,latitude,and ocean stratification.The results show that increased salt flux forcing and weakened background stratification both enhance the sinking of dense water,with geographical location(latitude)exerting a discernable impact.Based on these insights,the eddy viscosity coefficient,which characterizes vertical convective mixing in the parameterization scheme,is refined,with adjustments to its vertical structure and the incorporation of latitude dependence.It is preliminarily applied to simulate AMOC using the Community Earth System Model(CESM).The results demonstrate improvements in the simulation accuracy of seawater temperature at the near-surface and deep layers.Including the parameterization scheme of dense water sinking in the model leads to a reduction in the simulated intensity of AMOC at 26.5°N.In the high-latitude North Atlantic,the modification implemented in parameterization results in notable improvements in the simulation of seawater temperature,salinity,and density,with respective reductions in their root mean square errors of 4.36%,19.77%,and 1.84%.
基金by the National Science and Technology Major Project(Grant No.2019A-3307)the National Natural Science Foundation of China(Grant No.41872167)。
文摘The mode-I fracture toughness is of great significance for evaluating the fracturing ability of shale reservoirs.In this study,the mode-I fracture toughness of the shale in the Lower Silurian Longmaxi Formation,Southern Sichuan Basin was determined with the Cracked Chevron Notched Brazilian Disc(CCNBD).Based on the experimental data,the relationships among the mode-I fracture toughness,the density,the acoustic time and the clay mineral content were analyzed.The shale samples for fracture toughness test from cores were commonly limited,the investigation of fracture toughness using well logs was necessary.Therefore,a prediction model was proposed by correlating the fracture toughness with well logs responses.The results indicate that the fracture toughness of shale samples is from 0.4744 MPa$m1/2 to 1.0607 MPa$m1/2 with an average of 0.7817 MPa$m1/2,indicating that the anisotropy of fracture toughness of the Longmaxi Formation shale.The clay mineral content and the density have a positive effect on the fracture toughness,whereas the acoustic time plays a negative role on the fracture toughness.The clay mineral content has an important effect on the relationships among fracture toughness,acoustic time and density.The prediction model can provide continuous data of mode-I fracture toughness along the wellbore for field hydraulic fracturing operation,and it has certain guiding significance in the exploration and development of oil and gas reservoirs.
基金This research is supported by the National Science and Technology Major Project(Grant No.2019A-3307)the National Natural Science Foundation of China(Grant No.41872167).
文摘The acoustic response characteristics of shales were investigated by the acoustic transmission experiment,which is the basis of solving geological and engineering problems using the seismic or logging information during the process of the exploration and development of shale gas reservoirs.Based on the theory of acoustic wave and the background of acoustic transmission experiment,the initial condition,vibration source condition,boundary condition and stability condition were constructed,and the numerical simulation of acoustic transmission experiment of shales were completed through Matlab programming.The results show that under the same bedding angle,the acoustic time and attenuation coefficient of shales shown positive correlation with the bedding density;whereas under the same bedding density,the variation laws of the acoustic time and the attenuation coefficient of shales were more complex with the change of the bedding angle,that is,the acoustic time and attenuation coefficient of shales increased first,then decreased and then increased again with the increase of the bedding angle.
