The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismi...The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismic wave simulation with a data-constrained finite-fault rupture model.The constraint is implemented by identifying the optimal ground motion models(GMMs)through a scoring system that selects the best-fit GMMs to mid-and far-field China Earthquake Networks Center(CENC)seismic network data;and applying the optimal GMMs to refine the rupture model parameters for near-fault intensity field simulation.The simulated near-fault seismic intensity field reproduces seismic intensities collected from Myanmar’s sparse seismic network and concentrated in≥Ⅷintensity zones within 50 km of the projected fault plane;and identifies abnormal intensity regions exhibiting≥Ⅹintensity along the Meiktila-Naypyidaw corridor and near Shwebo that are attributed to soft soil amplification effects and near-fault directivity.This framework can also be applied to post-earthquake assessments in other similar regions.展开更多
This research focuses on the seismic responses of the historic masonry minarets,conducted through the creation of a digital twin model using finite element methods.The study initiated the development of a comprehensiv...This research focuses on the seismic responses of the historic masonry minarets,conducted through the creation of a digital twin model using finite element methods.The study initiated the development of a comprehensive model in the ANSYS Workbench,supplemented by operational modal analysis(OMA),to ascertain the dynamic characteristics of the minaret.The alignment of numerical and experimental frequency data was achieved using the response surface method(RSM)within ANSYS Workbench DesignXplorer.This process resulted in the establishment of a digital twin,accurately representing the physical minaret in a virtual environment.Blender^(■)software was then used to simulate the effects of two consecutive earthquakes in Türkiye that occurred on February 6,2023.The simulations highlighted the heightened susceptibility of the minaret,especially in its upper sections,to consecutive seismic activities,culminating in significant damage and collapse.This innovative approach,merging traditional engineering methods with a cutting-edge digital simulation,provides a profound insight into the seismic behavior of historical structures.The research underscores the importance of advanced seismic modeling for the effective preservation and resilience of architectural heritage sites against earthquake risks.展开更多
When simulating seismic wave propagation in free space, it is essential to introduce absorbing boundary conditions to eliminate reflections from artificially trtmcated boundaries. In this paper, a damping factor refer...When simulating seismic wave propagation in free space, it is essential to introduce absorbing boundary conditions to eliminate reflections from artificially trtmcated boundaries. In this paper, a damping factor referred to as the Gaussian dmping factor is proposed. The Gaussian damping factor is based on the idea of perfectly matched layers （PMLs）. This work presents a detailed analysis of the theoretical foundations and advantages of the Gaussian damping factor. Additionally, numerical experiments for the simulation of seismic waves are presented based on two numerical models： a homogeneous model and a multi-layer model. The results show that the proposed factor works better. The Gaussian damping factor achieves a higher Signal-to-Noise Ratio （SNR） than previously used factors when using same number of PMLs, and requires less PMLs than other methods to achieve an identical SNR.展开更多
US Vice President Al Gore's vision of Digital Earth applies us with prospects for brand-new ways of solving problems the earth is facing such as seismic disaster. ms paper first briefly introduces the concept of ...US Vice President Al Gore's vision of Digital Earth applies us with prospects for brand-new ways of solving problems the earth is facing such as seismic disaster. ms paper first briefly introduces the concept of Digital Earth. Then in the context of Digital Earth. the Origin, concept and application of Virtual Reality technology are reviewed. After that we present in detail our preliminary case study--CVR-USD (Computer Virtual Reality for Urban Seismic Disaster Simulation) System which aims to simulate and manage seismic disaster through integrating RS, GIS and VR technologies. For this system, we've built USD subsystem, developed SMVR software to implement CVR. and also developed a Spatial Dare Analysis Package to handle spatial data related to earthquake disaster.展开更多
Hybrid simulation is a powerful test method for evaluating the seismic performance of structural systems. This method makes it feasible that only critical components of a structure be experimentally tested. This paper...Hybrid simulation is a powerful test method for evaluating the seismic performance of structural systems. This method makes it feasible that only critical components of a structure be experimentally tested. This paper presents a newly proposed integration algorithm for seismic hybrid simulation which is aimed to extend its capabilities to a wide range of systems where existing methods encounter some limitations. In the proposed method, which is termed the variable time step （VTS） integration method, an implicit scheme is employed for hybrid simulation by eliminating the iterative phase on experimental element, the phase which is necessary in regular implicit applications. In order to study the effectiveness of the VTS method, a series of numerical investigations are conducted which show the successfulness of the VTS method in obtaining accurate, stable and converged responses. Then, in a comparative approach, the improved accuracy of the VTS method over commonly used integration methods is demonstrated. The stability of the VTS method is also studied and the results show that it provides conditional stability; however, its stability limit is well beyond the accuracy limit. The effect of time delay on the VTS method results is also investigated and it is shown that the VTS method is quite successful in handling this experimental error.展开更多
With the orthogonal design and the finite element methods, the outside stresses acting on the boundary and the inside tectonic stress field before the 1911 Honghai Bay earthquake are obtained. Under these stress field...With the orthogonal design and the finite element methods, the outside stresses acting on the boundary and the inside tectonic stress field before the 1911 Honghai Bay earthquake are obtained. Under these stress fields, the dislocation patterns of the faults are consistent with the observed ones. Using the softening unstabilization model for elastoplastic media to simulate the process of the earthquake occurrence, 5 moderate and strong earthquakes in these areas in this century are simulated. The results show that the moderate or strong earthquake happened only at the sections of the faults whose fault safety degree is zero. According to the present distribution of the fault safety degree, the authors predict the seismic risk zones there.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
Conventional seismic wave forward simulation generally uses mathematical means to solve the macroscopic wave equation,and then obtains the corresponding seismic wavefield.Usually,when the subsurface structure is finel...Conventional seismic wave forward simulation generally uses mathematical means to solve the macroscopic wave equation,and then obtains the corresponding seismic wavefield.Usually,when the subsurface structure is finely constructed and the continuity of media is poor,this strategy is difficult to meet the requirements of accurate wavefield calculation.This paper uses the multiple-relaxation-time lattice Boltzmann method(MRT-LBM)to conduct the seismic acoustic wavefield simulation and verify its computational accuracy.To cope with the problem of severe reflections at the truncated boundaries,we analogize the viscous absorbing boundary and perfectly matched layer(PML)absorbing boundary based on the single-relaxation-time lattice Boltzmann(SRT-LB)equation to the MRT-LB equation,and further,propose a joint absorbing boundary through comparative analysis.We give the specific forms of the modified MRT-LB equation loaded with the joint absorbing boundary in the two-dimensional(2D)and three-dimensional(3D)cases,respectively.Then,we verify the effects of this absorbing boundary scheme on a 2D homogeneous model,2D modified British Petroleum(BP)gas-cloud model,and 3D homogeneous model,respectively.The results reveal that by comparing with the viscous absorbing boundary and PML absorbing boundary,the joint absorbing boundary has the best absorption performance,although it is a little bit complicated.Therefore,this joint absorbing boundary better solves the problem of truncated boundary reflections of MRT-LBM in simulating seismic acoustic wavefields,which is pivotal to its wide application in the field of exploration seismology.展开更多
Seismic quantitative reservoir simulations and characterizations have played a vital role in exploring stratigraphic traps,such as lateaggradational lowstands prograding wedge systems(LPWS)within lowstands systems tra...Seismic quantitative reservoir simulations and characterizations have played a vital role in exploring stratigraphic traps,such as lateaggradational lowstands prograding wedge systems(LPWS)within lowstands systems tracts(LST).However,seismic data acquisition operations are always dominated by exceptional seismic coherent noise events,e.g.,multiples,which reduce the signal strengths of the sourcegenerated incident seismic waves within vertically and laterally heterogeneous earth systems.Hence,these noise events create hurdles in predicting paleo-depositional impedance(PDI),paleo-thickness(PTS),paleo-dense fractured networks,erosional and depositional zones,faultcontrolled migrations,and types of seismic reflection configurations(SRFC),which are key elements in developing stratigraphic pinch-out traps.This research utilizes the state-of-the-art technologies of spectral wavelet-based instantaneous time-frequency analysis and seismic waveform frequency-controlled porosity-constrained static reservoir simulation(FDPVS)tools to quantify the LPWS inside the Onshore Basin,Pakistan.The use of conventional amplitude-based seismic attributes,such as the average energy,remained a better tool for deciphering the overall geological architecture of the LPWS.Conventional FDPVS realizations resolved a PDI of−1.391 gm./c.c.^(*)m/s to−0.97 gm./c.c.^(*)m/s for LPWS with PTS of 12 and 20 m,respectively.A 0.9 km lateral extent of paleo-dense fractured networks(PDFN)with a strong linear regression R^(2)=0.93 was also resolved.Average energy attribute-based instantaneous frequency FDPVS realizations enabled the imaging of parallel-toprograding SRFC with resolved magnitudes of−0.259 gm./c.c.^(*)m/s for PDI,20 m for PTS,and 0.73 km for PDFN with linear regression transforms at R^(2)=0.92,which indicates the deposition of onlap fill facies inside the LPWS during extensive sea-level fall.These realizations have also resolved frequency-controlled fault migrations on 27-Hz spectral waveform-based amplitude plots with 2.174 gm./c.c.^(*)m/s PDI for conduit fault systems and 27-Hz with 0.585 gm./c.c.^(*)m/s PDI for sealing fault systems.All these structural configurations are completely sealed up by transgressive seals of transgressive systems tracts and,hence,developed into pure stratigraphic-based oil and gas plays.This research has strong implications for side-tracking drilling locations and provides an analogue for basins with similar geology and stratigraphy worldwide.展开更多
Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface...Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface. To address this challenge, we propose a novel numerical scheme that integrates the lattice Boltzmann method(LBM) and lattice spring model(LSM). In this scheme, LBM simulates viscoacoustic wave propagation in the fluid area and LSM simulates elastic wave propagation in the solid area. We also introduce three different LBM-LSM coupling strategies, a standard bounce back scheme, a specular reflection scheme, and a hybrid scheme, to describe wave propagation across fluid-solid boundaries. To demonstrate the accuracy of these LBM-LSM coupling schemes, we simulate wave propagation in a two-layer model containing a fluid-solid interface. We place excitation sources in the fluid layer and the solid layer respectively, to observe the wave phenomena when seismic waves propagate to interface from different sides. The simulated results by LBM-LSM are compared with the reference wavefields obtained by the finite difference method(FDM) and the analytical solution(ANA).Our LBM-LSM coupling scheme was verified effective, as the relative errors between the LBM-LSM solutions and reference solutions were within an acceptable range, sometimes around 1.00%. The coupled LBM-LSM scheme is further used to model seismic wavefields across a more realistic rugged seabed,which reveals the potential applications of the coupled LBM-LSM scheme in marine seismic imaging techniques, such as reverse-time migration and full-waveform inversion. The method also has potential applications in simulating wave propagation in complex two-and multi-phase media.展开更多
Since the development of ultrasonic pulse technique seismologists can study the seismic problems by simulation experiments in laboratries. In the 1950s Oliver (1954) conducted two-dimensional seismic model experimenta...Since the development of ultrasonic pulse technique seismologists can study the seismic problems by simulation experiments in laboratries. In the 1950s Oliver (1954) conducted two-dimensional seismic model experimental study. Henceforth geophysical model experiments have been conducted widly all over the world. In 1958 Zhao et al. of Peking University built the apparatures for seismic model experiments and did various model experiments (Zhao, 1986). In the 1960s, Birch (1960) measured the velocity of seismic waves in rocks under high pressure and first used the ultrasonic technique in the measurement of physical properties of rocks under high pressure. Since the end of the 1960s people paid attention to wave velocity anomaly as a seismic precursor, and simulation experiments of wave velocity anomoly have been developed (Nur, 1969; Liu and Lai, 1986; Liu, 1989). In the 1980s the developments of three-dimensional AE loation technique provided the conditions for study of seismic source mechanism in the laboratory (Kusunose, et al., 1981 ). All the experimental studies mentioned above used one-dimensional transducers. But the experiments require three-dimensional transducers with high precision to get accurate experimental data. We have manufactured three-dimensional transducers used in the laboratory,and they are able to stand high temperature and high pressure. By using the three-dimensional transducer in the laboratory the shape and the arrival times of longitudinal wave (P) and transverse wave in two polarization directions (S1, S2) can be measured simulataneously. Therefore, in the measurement of parameters of physical properties, the velocities, attenuation properties and frequency spectra of longitudinal wave (P) and transverse waves (S1, S2) can be measured with the same sample in the same experiemnt. Thus the problem caused by the difference in conditions of two experiments can be avoided. These trnasducers can also be used in model experiments and acoustic-wave position location, and under high temperature and high pressure conditions.展开更多
The Finite Difference （FD） method is an important method for seismic numerical simulations. It helps us understand regular patterns in seismic wave propagation, analyze seismic attributes, and interpret seismic data...The Finite Difference （FD） method is an important method for seismic numerical simulations. It helps us understand regular patterns in seismic wave propagation, analyze seismic attributes, and interpret seismic data. However, because of its discretization, the FD method is only stable under certain conditions. The Arbitrary Difference Precise Integration （ADPI） method is based on the FD method and adopts an integration scheme in the time domain and an arbitrary difference scheme in the space domain. Therefore, the ADPI method is a semi-analytical method. In this paper, we deduce the formula for the ADPI method based on the 3D elastic equation and improve its stability. In forward modeling cases, the ADPI method was implemented in 2D and 3D elastic wave equation forward modeling. Results show that the travel time of the reflected seismic wave is accurate. Compared with the acoustic wave field, the elastic wave field contains more wave types, including PS- and PP- reflected waves, transmitted waves, and diffracted waves, which is important to interpretation of seismic data. The method can be easily applied to elastic wave equation numerical simulations for eoloical models.展开更多
Strong ground motion of an earthquake is simulated by using both staggered grid finite difference method (FDM) and stochastic method, respectively. The acceleration time histories obtained from the both ways and their...Strong ground motion of an earthquake is simulated by using both staggered grid finite difference method (FDM) and stochastic method, respectively. The acceleration time histories obtained from the both ways and their response spectra are compared. The result demonstrates that the former is adequate to simulate the low-frequency seismic wave; the latter is adequate to simulate the high-frequency seismic wave. Moreover, the result obtained from FDM can better reflect basin effects.展开更多
The simulation of wave propagation in high-temperature media requires thermoelastic theory.In this paper,we apply the rotated-staggered-grid pseudo-spectral method(RSG-PSM)to solving thermoelastic governing equations ...The simulation of wave propagation in high-temperature media requires thermoelastic theory.In this paper,we apply the rotated-staggered-grid pseudo-spectral method(RSG-PSM)to solving thermoelastic governing equations based on L-S theory.A time splitting method is used to solve the stiffness problem of the equations,and we introduce the rotated staggered pseudo-spectral operator and centered pseudo-spectral operator to compute the first-order spatial derivatives and second-order spatial derivatives,respectively.In the case of the heterogeneous-medium model,the Crank-Nicolson explicit method is used instead of the pseudo-spectral method to compute the wavefield.The properties and propagation of the thermal coupled wavefield are discussed,and we compare the simulation results obtained using the pseudo-spectral method,staggered-grid pseudo-spectral method,and RSG-PSM.In the case of an isotropic homogeneous medium,we obtain stable and highly accurate results using the time splitting method combined with the RSG-PSM.However,the algorithm cannot be applied with a large time step when the thermal conductivity changes dramatically,and the algorithm is unstable when the reference temperature has a gradient distribution.The optimal combined application of the mesh generation mode and numerical algorithm is explored,laying a foundation for the extension of these methods to thermoporoelasticity,thermoviscoelasticity,and anisotropy.展开更多
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2023C01National Natural Science Foundation of China under Grant No.52478570Distinguished Young Scholars Program of the Natural Science Foundation of Heilongjiang Province,China under Grant No.JQ2024E002。
文摘The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismic wave simulation with a data-constrained finite-fault rupture model.The constraint is implemented by identifying the optimal ground motion models(GMMs)through a scoring system that selects the best-fit GMMs to mid-and far-field China Earthquake Networks Center(CENC)seismic network data;and applying the optimal GMMs to refine the rupture model parameters for near-fault intensity field simulation.The simulated near-fault seismic intensity field reproduces seismic intensities collected from Myanmar’s sparse seismic network and concentrated in≥Ⅷintensity zones within 50 km of the projected fault plane;and identifies abnormal intensity regions exhibiting≥Ⅹintensity along the Meiktila-Naypyidaw corridor and near Shwebo that are attributed to soft soil amplification effects and near-fault directivity.This framework can also be applied to post-earthquake assessments in other similar regions.
基金product of the research project titled,Video Camera Based Structural Health Monitoring of Historic Masonry Minarets and Development of a Long-Term Decision-Making Model Based on Deep Learning Method(Project No.222M140)supported by TÜBİTAK 1001-Scientific and the Technological Research Projects Support Program.
文摘This research focuses on the seismic responses of the historic masonry minarets,conducted through the creation of a digital twin model using finite element methods.The study initiated the development of a comprehensive model in the ANSYS Workbench,supplemented by operational modal analysis(OMA),to ascertain the dynamic characteristics of the minaret.The alignment of numerical and experimental frequency data was achieved using the response surface method(RSM)within ANSYS Workbench DesignXplorer.This process resulted in the establishment of a digital twin,accurately representing the physical minaret in a virtual environment.Blender^(■)software was then used to simulate the effects of two consecutive earthquakes in Türkiye that occurred on February 6,2023.The simulations highlighted the heightened susceptibility of the minaret,especially in its upper sections,to consecutive seismic activities,culminating in significant damage and collapse.This innovative approach,merging traditional engineering methods with a cutting-edge digital simulation,provides a profound insight into the seismic behavior of historical structures.The research underscores the importance of advanced seismic modeling for the effective preservation and resilience of architectural heritage sites against earthquake risks.
基金supported by the National Natural Science Foundation of China(No. 61072118)
文摘When simulating seismic wave propagation in free space, it is essential to introduce absorbing boundary conditions to eliminate reflections from artificially trtmcated boundaries. In this paper, a damping factor referred to as the Gaussian dmping factor is proposed. The Gaussian damping factor is based on the idea of perfectly matched layers （PMLs）. This work presents a detailed analysis of the theoretical foundations and advantages of the Gaussian damping factor. Additionally, numerical experiments for the simulation of seismic waves are presented based on two numerical models： a homogeneous model and a multi-layer model. The results show that the proposed factor works better. The Gaussian damping factor achieves a higher Signal-to-Noise Ratio （SNR） than previously used factors when using same number of PMLs, and requires less PMLs than other methods to achieve an identical SNR.
基金National Natural Science Foundation of China (NSFC)!project No. 69896250 Basic Research Project of CAS !project No. KJ951-B1
文摘US Vice President Al Gore's vision of Digital Earth applies us with prospects for brand-new ways of solving problems the earth is facing such as seismic disaster. ms paper first briefly introduces the concept of Digital Earth. Then in the context of Digital Earth. the Origin, concept and application of Virtual Reality technology are reviewed. After that we present in detail our preliminary case study--CVR-USD (Computer Virtual Reality for Urban Seismic Disaster Simulation) System which aims to simulate and manage seismic disaster through integrating RS, GIS and VR technologies. For this system, we've built USD subsystem, developed SMVR software to implement CVR. and also developed a Spatial Dare Analysis Package to handle spatial data related to earthquake disaster.
文摘Hybrid simulation is a powerful test method for evaluating the seismic performance of structural systems. This method makes it feasible that only critical components of a structure be experimentally tested. This paper presents a newly proposed integration algorithm for seismic hybrid simulation which is aimed to extend its capabilities to a wide range of systems where existing methods encounter some limitations. In the proposed method, which is termed the variable time step （VTS） integration method, an implicit scheme is employed for hybrid simulation by eliminating the iterative phase on experimental element, the phase which is necessary in regular implicit applications. In order to study the effectiveness of the VTS method, a series of numerical investigations are conducted which show the successfulness of the VTS method in obtaining accurate, stable and converged responses. Then, in a comparative approach, the improved accuracy of the VTS method over commonly used integration methods is demonstrated. The stability of the VTS method is also studied and the results show that it provides conditional stability; however, its stability limit is well beyond the accuracy limit. The effect of time delay on the VTS method results is also investigated and it is shown that the VTS method is quite successful in handling this experimental error.
文摘With the orthogonal design and the finite element methods, the outside stresses acting on the boundary and the inside tectonic stress field before the 1911 Honghai Bay earthquake are obtained. Under these stress fields, the dislocation patterns of the faults are consistent with the observed ones. Using the softening unstabilization model for elastoplastic media to simulate the process of the earthquake occurrence, 5 moderate and strong earthquakes in these areas in this century are simulated. The results show that the moderate or strong earthquake happened only at the sections of the faults whose fault safety degree is zero. According to the present distribution of the fault safety degree, the authors predict the seismic risk zones there.
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This work is supported in part by the National Natural Science Foundation of China(U19B6003-04-01,42204132,41874130)R&D Department of CNPC(2022DQ0604-01)China Postdoctoral Science Foundation(2020M680667,2021T140661).
文摘Conventional seismic wave forward simulation generally uses mathematical means to solve the macroscopic wave equation,and then obtains the corresponding seismic wavefield.Usually,when the subsurface structure is finely constructed and the continuity of media is poor,this strategy is difficult to meet the requirements of accurate wavefield calculation.This paper uses the multiple-relaxation-time lattice Boltzmann method(MRT-LBM)to conduct the seismic acoustic wavefield simulation and verify its computational accuracy.To cope with the problem of severe reflections at the truncated boundaries,we analogize the viscous absorbing boundary and perfectly matched layer(PML)absorbing boundary based on the single-relaxation-time lattice Boltzmann(SRT-LB)equation to the MRT-LB equation,and further,propose a joint absorbing boundary through comparative analysis.We give the specific forms of the modified MRT-LB equation loaded with the joint absorbing boundary in the two-dimensional(2D)and three-dimensional(3D)cases,respectively.Then,we verify the effects of this absorbing boundary scheme on a 2D homogeneous model,2D modified British Petroleum(BP)gas-cloud model,and 3D homogeneous model,respectively.The results reveal that by comparing with the viscous absorbing boundary and PML absorbing boundary,the joint absorbing boundary has the best absorption performance,although it is a little bit complicated.Therefore,this joint absorbing boundary better solves the problem of truncated boundary reflections of MRT-LBM in simulating seismic acoustic wavefields,which is pivotal to its wide application in the field of exploration seismology.
文摘Seismic quantitative reservoir simulations and characterizations have played a vital role in exploring stratigraphic traps,such as lateaggradational lowstands prograding wedge systems(LPWS)within lowstands systems tracts(LST).However,seismic data acquisition operations are always dominated by exceptional seismic coherent noise events,e.g.,multiples,which reduce the signal strengths of the sourcegenerated incident seismic waves within vertically and laterally heterogeneous earth systems.Hence,these noise events create hurdles in predicting paleo-depositional impedance(PDI),paleo-thickness(PTS),paleo-dense fractured networks,erosional and depositional zones,faultcontrolled migrations,and types of seismic reflection configurations(SRFC),which are key elements in developing stratigraphic pinch-out traps.This research utilizes the state-of-the-art technologies of spectral wavelet-based instantaneous time-frequency analysis and seismic waveform frequency-controlled porosity-constrained static reservoir simulation(FDPVS)tools to quantify the LPWS inside the Onshore Basin,Pakistan.The use of conventional amplitude-based seismic attributes,such as the average energy,remained a better tool for deciphering the overall geological architecture of the LPWS.Conventional FDPVS realizations resolved a PDI of−1.391 gm./c.c.^(*)m/s to−0.97 gm./c.c.^(*)m/s for LPWS with PTS of 12 and 20 m,respectively.A 0.9 km lateral extent of paleo-dense fractured networks(PDFN)with a strong linear regression R^(2)=0.93 was also resolved.Average energy attribute-based instantaneous frequency FDPVS realizations enabled the imaging of parallel-toprograding SRFC with resolved magnitudes of−0.259 gm./c.c.^(*)m/s for PDI,20 m for PTS,and 0.73 km for PDFN with linear regression transforms at R^(2)=0.92,which indicates the deposition of onlap fill facies inside the LPWS during extensive sea-level fall.These realizations have also resolved frequency-controlled fault migrations on 27-Hz spectral waveform-based amplitude plots with 2.174 gm./c.c.^(*)m/s PDI for conduit fault systems and 27-Hz with 0.585 gm./c.c.^(*)m/s PDI for sealing fault systems.All these structural configurations are completely sealed up by transgressive seals of transgressive systems tracts and,hence,developed into pure stratigraphic-based oil and gas plays.This research has strong implications for side-tracking drilling locations and provides an analogue for basins with similar geology and stratigraphy worldwide.
基金supported in part by R & D Department of China National Petroleum Corporation (2022DQ0604-01)National Natural Science Foundation of China (42204132)+3 种基金the China Postdoctoral Science Foundations (2020M680667, 2021T140661)Harvard-CUP Joint Laboratory on Petroleum Science“111” project (B13010)the financial support from the CAS Special Research Assistant Project。
文摘Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface. To address this challenge, we propose a novel numerical scheme that integrates the lattice Boltzmann method(LBM) and lattice spring model(LSM). In this scheme, LBM simulates viscoacoustic wave propagation in the fluid area and LSM simulates elastic wave propagation in the solid area. We also introduce three different LBM-LSM coupling strategies, a standard bounce back scheme, a specular reflection scheme, and a hybrid scheme, to describe wave propagation across fluid-solid boundaries. To demonstrate the accuracy of these LBM-LSM coupling schemes, we simulate wave propagation in a two-layer model containing a fluid-solid interface. We place excitation sources in the fluid layer and the solid layer respectively, to observe the wave phenomena when seismic waves propagate to interface from different sides. The simulated results by LBM-LSM are compared with the reference wavefields obtained by the finite difference method(FDM) and the analytical solution(ANA).Our LBM-LSM coupling scheme was verified effective, as the relative errors between the LBM-LSM solutions and reference solutions were within an acceptable range, sometimes around 1.00%. The coupled LBM-LSM scheme is further used to model seismic wavefields across a more realistic rugged seabed,which reveals the potential applications of the coupled LBM-LSM scheme in marine seismic imaging techniques, such as reverse-time migration and full-waveform inversion. The method also has potential applications in simulating wave propagation in complex two-and multi-phase media.
文摘Since the development of ultrasonic pulse technique seismologists can study the seismic problems by simulation experiments in laboratries. In the 1950s Oliver (1954) conducted two-dimensional seismic model experimental study. Henceforth geophysical model experiments have been conducted widly all over the world. In 1958 Zhao et al. of Peking University built the apparatures for seismic model experiments and did various model experiments (Zhao, 1986). In the 1960s, Birch (1960) measured the velocity of seismic waves in rocks under high pressure and first used the ultrasonic technique in the measurement of physical properties of rocks under high pressure. Since the end of the 1960s people paid attention to wave velocity anomaly as a seismic precursor, and simulation experiments of wave velocity anomoly have been developed (Nur, 1969; Liu and Lai, 1986; Liu, 1989). In the 1980s the developments of three-dimensional AE loation technique provided the conditions for study of seismic source mechanism in the laboratory (Kusunose, et al., 1981 ). All the experimental studies mentioned above used one-dimensional transducers. But the experiments require three-dimensional transducers with high precision to get accurate experimental data. We have manufactured three-dimensional transducers used in the laboratory,and they are able to stand high temperature and high pressure. By using the three-dimensional transducer in the laboratory the shape and the arrival times of longitudinal wave (P) and transverse wave in two polarization directions (S1, S2) can be measured simulataneously. Therefore, in the measurement of parameters of physical properties, the velocities, attenuation properties and frequency spectra of longitudinal wave (P) and transverse waves (S1, S2) can be measured with the same sample in the same experiemnt. Thus the problem caused by the difference in conditions of two experiments can be avoided. These trnasducers can also be used in model experiments and acoustic-wave position location, and under high temperature and high pressure conditions.
基金supported by the National Science and Technology Major Project of China(Grant No. 2011ZX05004-003,2011ZX05014-006-006)the National Key Basic Research Program of China(Grant No. 2013CB228602)the Natural Science Foundation of China(Grant No. 40974066)
文摘The Finite Difference （FD） method is an important method for seismic numerical simulations. It helps us understand regular patterns in seismic wave propagation, analyze seismic attributes, and interpret seismic data. However, because of its discretization, the FD method is only stable under certain conditions. The Arbitrary Difference Precise Integration （ADPI） method is based on the FD method and adopts an integration scheme in the time domain and an arbitrary difference scheme in the space domain. Therefore, the ADPI method is a semi-analytical method. In this paper, we deduce the formula for the ADPI method based on the 3D elastic equation and improve its stability. In forward modeling cases, the ADPI method was implemented in 2D and 3D elastic wave equation forward modeling. Results show that the travel time of the reflected seismic wave is accurate. Compared with the acoustic wave field, the elastic wave field contains more wave types, including PS- and PP- reflected waves, transmitted waves, and diffracted waves, which is important to interpretation of seismic data. The method can be easily applied to elastic wave equation numerical simulations for eoloical models.
基金National Natural Science Foundation of China (5048003) and DAAD of Munich University, Germany.
文摘Strong ground motion of an earthquake is simulated by using both staggered grid finite difference method (FDM) and stochastic method, respectively. The acceleration time histories obtained from the both ways and their response spectra are compared. The result demonstrates that the former is adequate to simulate the low-frequency seismic wave; the latter is adequate to simulate the high-frequency seismic wave. Moreover, the result obtained from FDM can better reflect basin effects.
基金supported by the National Natural Science Foundation of China(Grant Nos.41874125,and 41430322)the National Key Research and Development Project(Grant Nos.2018YFC0603701,and 2017YFC06061301).
文摘The simulation of wave propagation in high-temperature media requires thermoelastic theory.In this paper,we apply the rotated-staggered-grid pseudo-spectral method(RSG-PSM)to solving thermoelastic governing equations based on L-S theory.A time splitting method is used to solve the stiffness problem of the equations,and we introduce the rotated staggered pseudo-spectral operator and centered pseudo-spectral operator to compute the first-order spatial derivatives and second-order spatial derivatives,respectively.In the case of the heterogeneous-medium model,the Crank-Nicolson explicit method is used instead of the pseudo-spectral method to compute the wavefield.The properties and propagation of the thermal coupled wavefield are discussed,and we compare the simulation results obtained using the pseudo-spectral method,staggered-grid pseudo-spectral method,and RSG-PSM.In the case of an isotropic homogeneous medium,we obtain stable and highly accurate results using the time splitting method combined with the RSG-PSM.However,the algorithm cannot be applied with a large time step when the thermal conductivity changes dramatically,and the algorithm is unstable when the reference temperature has a gradient distribution.The optimal combined application of the mesh generation mode and numerical algorithm is explored,laying a foundation for the extension of these methods to thermoporoelasticity,thermoviscoelasticity,and anisotropy.
