A method for elastic wave modeling up to tilted orthorhombic symmetry in anisotropy involves applying a curved grid adapting to a free-surface topography and transforming this the curved grid to a rectangular grid. Calculations using numerical discretization methods such as finite-difference are performed. The boundary condition for any free-surface is .sub.ij.Math.n.sub.j=0, which requires vanishing the global stresses' normal components to the free-surface. This resulting model more accurately simulates surface effects and better inversion for subsurface earth properties.

Embodiments of a method for implementing a finite difference time domain modeling with multiple APCs are disclosed herein. The disclosed methods and systems overcome the memory capacity limitation of APCs by having each APC perform multiple timesteps on a small piece of the computational domain or data volume in a APC queued manner. The cost of transferring data between host and compute accelerator can then be amortized over multiple timesteps, greatly reducing the amount of PCI bandwidth required to sustain high propagation speeds. The APC queued nature of the algorithm achieves linear scaling of PCI throughput with increasing number of APCs, allowing the algorithm to scale up to many dozens of APCs in some embodiments.

A method of modeling an aquatic environment or locating an acoustic source in the aquatic environment. A range-dependent medium is approximated in terms of a series of range-independent regions and obtaining single-scattering solutions across the vertical interfaces between regions. One or more acoustic waves are propagated from a known acoustic source through the range-dependent medium to one or more known seismoacoustic receivers to model iteratively the various solid and liquid layers of the range-dependent medium. Alternatively, one or more acoustic waves are reverse-propagated from one or more known seismoacoustic receivers through the range-dependent medium to determine whether an acoustic source is present within a user-defined range.

The presently disclosed seismic acquisition technique employs a receiver array and a processing methodology that are designed to attenuate the naturally occurring seismic background noise recorded along with the seismic data during the acquisition. The approach leverages the knowledge that naturally occurring seismic background noise moves with a slower phase velocity than the seismic signals used for imaging and inversion and, in some embodiments, may arrive from particular preferred directions. The disclosed technique comprises two steps: 1) determining from the naturally occurring seismic background noise in the preliminary seismic data a range of phase velocities and amplitudes that contain primarily noise and the degree to which that noise needs to be attenuated, and 2) designing an acquisition and processing method to attenuate that noise relative to the desired signal.

Improved finite-difference staggered grid wave propagation systems and methods. One illustrative computer-based wave field simulation method includes: applying at least one signal to a grid of model cells forming a model space, each model cell having stress values associated with stress nodes and velocity values associated with velocity nodes staggered from the stress nodes; and propagating the at least one signal as a wave into the model space by alternately updating the stress values and the velocity values to obtain a time-dependent wave field associated with the at least one signal. The stress value updating includes, for each model cell: determining spatial derivatives of the velocity values for the model cell; interpolating the spatial derivatives to multiple stress nodes within the model cell; and, for each stress node within the model cell, combining the spatial derivatives associated with that stress node to update at least one stress value associated with that stress node.

Method for multi-parameter inversion using elastic inversion. This method decomposes data into offset/angle groups and performs inversion on them in sequential order. This method can significantly speed up convergence of the iterative inversion process, and is therefore most advantageous when used for full waveform inversion (FWI). The present inventive approach draws upon relationships between reflection energy and reflection angle, or equivalently, offset dependence in elastic FWI. The invention uses recognition that the amplitudes of small angle (near offset) reflections are largely determined by acoustic impedance alone (1), independent for the most part of Vp/Vs. Large angle (middle and far offset) reflections are affected by Ip, Vp/Vs (2) and other earth parameters such as density (3) and anisotropy. Therefore, the present inventive method decomposes data into angle or offset groups in performing multi-parameter FWI to reduce crosstalk between the different model parameters being determined in the inversion.

Systems and methods are disclosed. The method includes obtaining seismic data for a geological region of interest, a velocity model, and an attenuation model. The seismic data includes an amplitude and a phase of seismic waves traveling from a seismic source location. The method further includes determining a traveltime model using the seismic source location, the velocity model, and a traveltime Eikonal function and determining an attenuated traveltime model using a parallel fast sweeping method. The parallel fast sweeping method includes Cuthill-McKee ordering a plurality of grid nodes. The plurality of grid nodes represents the geological region of interest. The parallel fast sweeping method further includes using the seismic source location, the velocity model, the attenuation model, the traveltime model, and an attenuated traveltime Eikonal function. The method still further includes generating an updated attenuation model using the attenuated traveltime model, the amplitude, and the phase.

A method of modeling an aquatic environment or locating an acoustic source in the aquatic environment. A range-dependent medium is approximated in terms of a series of range-independent regions and obtaining single-scattering solutions across the vertical interfaces between regions. One or more acoustic waves are propagated from a known acoustic source through the range-dependent medium to one or more known seismoacoustic receivers to model iteratively the various solid and liquid layers of the range-dependent medium. Alternatively, one or more acoustic waves are reverse-propagated from one or more known seismoacoustic receivers through the range-dependent medium to determine whether an acoustic source is present within a user-defined range.

A method includes receiving field seismic data that represents a subsurface, identifying features in the field seismic data using a machine learning model that was trained using at least one first synthetic seismic data set that includes one or more features and one or more labels of the features, and at least one second synthetic seismic data set, the first and second synthetic seismic data sets both generated based on a geological model. Noise is injected into the second synthetic seismic data based on the geological model. The method also includes generating a model of the subsurface based at least in part on the features that were identified in the field seismic data using the machine learning model.

A computer-implemented method for determining modeled seismic data of a subsurface region includes receiving observed seismic data from the subsurface region captured by one or more seismic receivers as one or more reflected seismic signals; determining, based on a velocity model of the subsurface region and the observed seismic data, a traveltime function associated with the subsurface region; migrating, using the traveltime function and a Kirchhoff migration operator, the observed seismic data to produce a migrated seismic image; and performing reverse-time demigration on the migrated seismic image, using the velocity model and a solved full wave-equation, to produce modeled seismic data.