For seismic exploration, the coupling problem between different physical fields is unavoidable. The operation of the coupling interface is very tricky. For this challenge, we propose a unified numerical approach to overcome it. Specifically, we construct a model framework, which contains various physical phenomena, and solve it by using the discontinuous Galerkin (DG) method allowing for the jump of the solution across the interface between the fluids and the solid materials. The viscoelasticity and fracture are first incorporated into the coupled model. The model includes the anisotropy, viscoelasticity, and fracture properties. The Riemann solver is employed to handle the coupling interfaces: the acoustic-elastic contact, the acoustic-viscoelastic contact, and the elastic-viscoelastic contact. Any additional treatment is not required for the complex coupling interface. Several examples are used to demonstrate the validity and flexibility of the proposed numerical scheme and the corresponding results show that our approach can handle more complex coupled models efficiently.

The seismic coherence attribute is one of the most typically used seismic discontinuity feature detection technologies, which is widely used in fault detection, channel boundary characterization, and other occasions. The eigen-structure-based coherence algorithm possesses the property of stability by using the eigenvalues of seismic data’s covariance matrix, but in the algorithm, only the eigenvalues are used to calculate the final coherence value, and the information contained in eigenvectors is ignored. Through analysis, it is found that the elements in the eigenvectors represent the energy differences of seismic traces. By directly measuring the difference of different elements in an eigenvector, the energy differences between different seismic records can be effectively measured. Since the seismic data on both sides of some discontinuous boundaries, such as channel boundaries, principally show amplitude differences, the coherence properties based on eigenvectors can better characterize them. Through theoretical analysis, model testing, and case application, this letter illustrates the reliability of the proposed algorithm.

Elastic wavefield separation has attracted much attention in the field of geophysics, but the focus is mainly on a single solid medium, which is hardly used in the coupled medium. We propose an effective discontinuous Galerkin (DG) approach with the exact Riemann solver for modeling decoupling P- and S- wavefield propagation in coupling solid-fluid media. We apply the selective strong attenuation to P- or S-waves by the viscoelastic theory while keeping the other wave mode. The viscoelastic wave equation is first cast into the decoupling wave equation. Following, we derive a novel exact Riemann solver that can accurately couple with the fluid and the decoupling elastic media. Finally, we use the DG method to solve P/S decoupling wave equations in triangular and tetrahedral meshes. The original wavefield is accurately decomposed into P and S wavefields, whose phases and amplitudes are consistent with those of the elastic data. Several numerical experiments are used to demonstrate the accuracy and capacity of our developed P/S-separated approach.

Poroelastic wave equations incorporating fluid information have been paid much attention to, however, the conventional perfectly matched layer (PML) scheme fails to absorb poroelastic waves in numerical modeling. In this work, we construct a unified framework of the combination of the low- and high-order unsplit complex-frequency-shifted (CFS) -PMLs with the discontinuous Galerkin (DG) method in poroelastic media. We have derived three kinds of PML-corrected poroelastic wave equations, including the split PML formula, the low-order unsplit CFS-PML formula, and the high-order unsplit CFS-PML formula, which are all first-order hyperbolic form. We give a general scheme for transforming the second-order poroelastic equation into a first-order hyperbolic system. These PML-corrected formulations can be numerically solved by the DG method for simulating wave propagation in single-, double-, and triple-porosity media. Several numerical experiments in isotropic and anisotropic multi-porosity media are used to demonstrate the effectiveness of the low- and high-order unsplit auxiliary differential equation (ADE) CFS-PML boundary conditions for wavefield simulation. The model with a sinusoidal irregular interface is discretized into unstructured triangular meshes, and its results are to validate the flexibility of a combination of the low- and high-order unsplit CFS-PMLs with the DG method for simulation of seismic wave propagation in poroelastic media.

The dips of underground reflectors indicate their trends and provide a wealth of information about geological structures. It is widely used in seismic data processing and interpretation. The time-frequency spectrum (TFS) can be directly used for dip estimation, and TFS can be obtained by spectrum decomposition techniques such as short-time Fourier transform, Stockwell transform, and continuous wavelet transform. In spectrum decomposition technologies, seismic data are usually multiplied by a window function in the time domain. At the same travel time, all traces in the seismic data are multiplied by the same window function, which burrs the difference in dip and leads to errors in dip estimation. To solve this problem, this letter advocates an algorithm that uses the dip to guide the window function. To enhance the robustness of the algorithm, we introduce the energy weighted average algorithm, and Hilbert transform, into the algorithm. The model testing has verified that our algorithm can estimate dips accurately, and the application of field seismic data has proved the practicability of this algorithm.