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
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.
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.
