98 results about "Acoustic wave equation" patented technology

A frequency domain optimization mixture staggered grid finite difference forward modeling method comprises the following steps: 1) providing a time-domain two-dimension sound wave equation; 2) eliminating artificial boundary reflection and obtaining a time-domain two-dimension sound wave equation with a perfectly-matched layer boundary condition; 3) performing Fourier transform on time variables at the two sides of the equation and obtaining a frequency-domain sound wave equation; 4) carrying out finite difference discretization on the frequency-domain sound wave equation with the perfectly-matched layer boundary condition based on a conventional staggered grid and obtaining a finite difference discretization format; 5) carrying out finite difference discretization on the frequency-domain sound wave equation with the perfectly-matched layer boundary condition based on a rotation staggered grid and obtaining a finite difference discretization format; 6) performing optimization mixing on the conventional staggered grid and the rotation staggered grid, grid difference item being weighted average of the grid difference item in the two grid systems, and quality acceleration item being weighted average of a center point and eight points around the center point; and 7) under the criterion of the minimum phase velocity error, calculating an optimized coefficient. The weighting coefficient enables frequency dispersion error due to the finite difference discretization to be the smallest, and the precision of the frequency-domain forward modeling is greatly improved.

The invention relates to an acoustic anisotropic reverse-time migration mixing method. A reverse-time migration imaging process is divided into the following steps: 1, setting an observation system and a seismic source location when no seismic data is input to obtain seismic data in anisotropic media, and solving an anisotropic acoustic wave equation by a mixed pseudo-spectral method and an finitedifference method, wherein during application of the finite difference method, high-order rotating staggered grids are adopted to ensure the calculation accuracy and stability, and only one fast Fourier transform is needed at each time step; and 2, applying an improved excitation amplitude imaging condition according to the input seismic data to perform inverse-time migration imaging. The forwardseismic transmission process and the reverse seismic record transmission process are carried out based on the above algorithm, and then reverse-time migration imaging is carried out. The need for computational memory is reduced in a wide range of computational areas. The calculation efficiency of reverse-time migration is improved, seismic acoustic recording is simulated in a large scale of complex anisotropic media, and reverse-time migration imaging is performed.

The invention discloses a full-waveform inversion method based on dynamic random seismic source coding. The invention discloses a dynamic random seismic source coding new strategy, belongs to the field of geophysics, and provides a dynamic random seismic source coding new strategy by randomly selecting four aspects of amplitude, phase, polarity and shot point position of a seismic source, which comprises the following main steps of: randomly selecting actual shots and time coding sequence convolution, and synthesizing a super shot profile; calculating a super shot residual error, a gradient direction and an optimal step length; inversion iteration is carried out, and target parameters are updated; and judging whether an inversion termination condition is met or not. Crosstalk noise betweenshots is avoided, and the inversion efficiency is greatly improved on the premise that the inversion precision is not affected. The new dynamic random seismic source coding strategy is introduced into the solution of the L-BFGS algorithm of the variable density acoustic wave equation full waveform inversion, the crosstalk influence of the medium density and the acoustic wave speed during the synchronous inversion is effectively reduced, and the full waveform inversion speed is improved.

The invention discloses a staggered mesh forward modeling method based on time-space domain optimization. According to the method, a plane wave general solution of a first order pressure intensity-speed partial differential equation set is solved, a pressure intensity field and polarization speed field analysis expression of a first order sound wave equation is acquired, a traditional space staggering grid difference format is combined with a precise time recursion format to acquire a precise staggering time recursion format, and least square iteration solution is lastly employed to acquire a high precision staggering grid difference operator for forward modeling. The method is advantaged in that value frequency dispersion is improved to a certain degree, phase velocity precision is improved, and the substantial effect can be realized under high-order conditions.