A method can include accessing a model of a subterranean region where the model includes a fault that corresponds to a fault in the subterranean region; via a first side of the fault, outwardly radiating therefrom cells of the model with a first type of radiation and, via a second, opposing side of the fault, outwardly radiating therefrom cells of the model with a second type of radiation; and, based at least in part on the outwardly radiating of the first type of radiation and the outwardly radiating of the second type of radiation, assigning a portion of the cells of the model a sidedness property value with respect to the fault that indicates that each cell in the portion of the cells is assigned to the first side of the fault or assigned to the second side of the fault

A pulsed sinusoidal acoustic signal transmitted through a subsurface volume of a wellbore may be detected. A time-reversed acoustic signal of the pulsed sinusoidal acoustic signal may be transmitted through the subsurface volume of the wellbore. Transmission of the time-reversed acoustic signal through the subsurface volume of the wellbore may result in generation of focused acoustic signal in the subsurface volume of the wellbore. The focused acoustic signal in the subsurface volume of the wellbore may be detected, and the integrity of the wellbore may be determined based on the focused acoustic signal in the subsurface volume of the wellbore.

A method for subsurface fault extraction using undirected graphs is provided. Extracting faults in the subsurface may assist in various stages of geophysical prospecting. To that end, an undirected graph may be used in order to identify distinctive fault branches in the subsurface. Fault probability data, from seismic data, may be used to establish connections in the undirected graph. Thereafter, some of the connections in the undirected graph may be removed based on analyzing one or more attributes, such as dip, azimuth, or context, associated with the connections or nodes associated with the connections. After which, the undirected graph may be analyzed in order to extract the faults in the subsurface.

A methodology for discontinuous smooth interpolation in order to generate a curve of a discontinuous volume due to one or more faults in a subsurface is disclosed. Faults in a subsurface result in discontinuities in the subsurface. Hydrocarbon management may seek to determine various surfaces in the subsurface, including across the faults in the subsurface. To generate the various surfaces, a continuous formulation of the interpolation method is followed in which discontinuous smooth interpolation is viewed as a variational optimization problem (such as an energy optimization problem) for the surface curvature function. In this way, the methodology does not require that the input data be located at grid points and discretized with a structured regular grid. Rather, because a continuous function is used, an unstructured grid may also be used to discretize the resulting equation.

Disclosed herein are geologic modeling methods and systems employing function-based representations of horizons intersected by partial faults. An illustrative method embodiment includes: (a) obtaining a seismic image volume; (b) identifying a horizon within the seismic image volume, said horizon being intersected by a partial fault; (c) deriving a function-based representation of the horizon, the representation being continuous except across the partial fault; (e) constructing a watertight subsurface model using the function-based representation; (f) assigning petrophysical parameter values to compartments of the watertight subsurface model; and, optionally, (g) storing or displaying the watertight subsurface model.

A method can include receiving seismic image data of a geologic region and interpretation information of the seismic image data for a geologic feature in the geologic region, where the seismic image data include a geologic feature class imbalance; shifting the geologic feature class imbalance toward a class of the geologic feature by increasing the spatial presence of the geologic feature in the seismic image data to generate training data; and training a neural network using the training data to generate a trained neural network.

Systems and methods develop a three-dimensional model of a subterranean formation based on vertical seismic profiles at a plurality of well locations. This approach can include receiving seismic data for the subterranean formation including the vertical seismic profiles; for each vertical seismic profile, injecting a ground force into the vertical seismic profile to provide a reference trace at depth zero to estimate energy loss in each receiver providing data in the vertical seismic profile and estimating time and depth variant quality factors for the well location associated with the vertical seismic profile based on the seismic profile; estimating quality factors for points within a three-dimensional volume representing the subterranean formation by interpolating between the time and depth variant quality factors for the location associated with each vertical seismic profile; and combining estimated quality factors to generate a three-dimensional quality factor model of the three-dimensional volume representing the subterranean formation.

This disclosure presents a fault prediction system using a deep learning neural network, such as a convolutional neural network. The fault prediction system utilizes as input seismic data, and then derives various seismic attributes from the seismic data. In various aspects, the seismic attributes can be normalized and have importance coefficients determined. A sub-set of seismic attributes can be selected to reduce computing resources and processing time. The deep learning neural network can utilize the seismic data and seismic attributes to determine parameterized results representing fault probabilities. The fault prediction system can utilize the fault probabilities to determine fault predictions which can be represented as a predicted new seismic data, such as using a three-dimensional image.

Geologic modeling methods and systems may use design-space to design-space mapping to facilitate simulation grid generation for multiple interpretations of a subsurface region. As one example, one or more embodiments of a geologic modeling method may comprise: obtaining first and second geologic models having different structural interpretations of a subsurface region; mapping each of the geologic models to associated design space models representing an unfaulted subsurface region; determining a design-to-design space mapping from the first design space model to the second design space model; using said mapping to copy parameter values from the first design space model to the second of the design space model; gridding each of the design space models to obtain design space meshes; partitioning cells in the first and second design space meshes along faults; reverse mapping the partitioned design space meshes to the physical space to obtain first and second physical space simulation meshes.

Disclosed is a method of determining front propagation within a subsurface volume such as a reservoir. The subsurface volume includes a plurality of cells and at least one geological fault. The method includes performing a fast marching algorithm so as to determine the front propagation in terms of the time of arrival of the front at a particular cell from one or more neighboring cells which make up the neighborhood of the particular cell. For each faulted cell that is adjacent a geological fault, the neighborhood of the faulted cell is defined as including only its geometric neighbors, where the geometric neighbors are those cells that are in contact with the faulted cell in a geometric sense, regardless of stratification.