Apparatus, methods, and systems for determining acoustic velocity behind casing or tubing in a subterranean wellbore. A method may include obtaining a plurality of waveform data sets corresponding to a plurality of propagation path regimes and obtaining a total wavefield across the receiver array. The method may also include determining a Green's function representing each of the plurality of propagation path regimes and determining a noise wavefield by convolving the Green's functions and a known transmitted pressure signal corresponding to the plurality of waveform data sets. The method may also include generating a reduced-noise wavefield by subtracting the noise wavefield from the total wavefield and estimating the acoustic velocity of a formation behind the casing or tubing from the reduce-noise wavefield.

Method for acquiring, at reduced acquisition cost, seismic data using simultaneous, field-encoded sources in the field (702), and then constructing pseudo source-records (703) that better meet the requirements for using additional simultaneous computer-encoded sourcing for computer simulations or forward modeling (706) as part of (707) iterative FWI (Full Wavefield Inversion) or RTM (Reverse Time Migration), with additional reduction in computational costs. By better meeting the requirements of simultaneous sourcing for FWI or RTM (701), artifacts and crosstalk are reduced in the output. The method can be used for marine streamer acquisition and other non-fixed spread geometries to acquire both positive and negative offsets and to mitigate the “missing data” problem for simultaneous-source FWI. It can also be used for land data to overcome issues with moving spreads and long continuous records.

This disclosure is directed to methods and systems to evaluate noise contend of seismic data received during a marine survey. The seismic data includes pressure and particle motion data generated by collocated pressure and particle motion sensors of a seismic data acquisition system. The pressure and particle motion data are cross ghosted and temporal and spatial wavelet transforms are applied to the cross-ghosted pressure and particle motion data in order to compute pressure energies and particle motion energies in temporal and spatial scales of a temporal and spatial scale domain. The pressure and particle motion energies may be compared to evaluate noise content in the pressure and particle motion data, evaluate changes in the noise content during the marine survey, and adjust marine survey parameters to reduce the noise content.

There is provided herein a new system and method of local attribute match filtering which operates in the local attribute domain via the use of complex wavelet transform technology. This approach is adaptable to address various noise types in seismic data and, more particularly, is well suited to reduce the noise in geophone data as long as an associated hydrophone signal is relatively noise-free.

A method and a system for implementing the method are disclosed wherein the source wavelet, input parameter models, and seismic input data may be obtained from a non-flat surface, sometimes mild, or foothill topography as well as the shot and receiver lines might not necessarily be straight, and often curve to avoid obstacles on the land surface. In particular, the method and system disclosed, suppresses low wavenumber and low frequency noises, by balancing lateral and vertical amplitudes to produce an image of subsurface reflectors located within a survey area having higher lateral resolutions and wavenumbers, as well as higher high-cut frequencies, and lower low-cut frequencies in complex media, than could otherwise not be achieved by other methods commonly known in the art.

Techniques to improve the measurement of electromagnetic fields based on noise cancellation are disclosed. Sensors placed at the earth's surface measure electromagnetic fields emanating from within the earth, and/or perform electromagnetic telemetry. In one embodiment, signal processing techniques are applied to the acquired signals, either in real time or near real time to reduce or cancel the noise to enable the signal of interest to be measured. In another embodiment, the location of the plurality of sensors is judiciously chosen to improve the measurement of the signal of interest.

Systems and methods for determining object location may include a memory and a processor. The processor may be configured to collect seismic data and geophysical data to determine object location. The processor may be configured to determine one or more seismic attributes associated with a plurality types of noises based on the seismic data and the geophysical data using one or more machine learning algorithms. The processor may be configured to eliminate unwanted noises from noise classifications based on the one or more seismic attributes. The processor may be configured to predict the object location by comparing time and velocity data of the object with recorded timing and velocity data. The processor may be configured to validate the object location by comparing the determined noise with image data. The systems and methods may be used in, for example, detecting missing planes such as Malaysian Airlines Flight 370.

The present invention discloses a focus-stacking imaging method and system based on correlation-based seismic interferometry. The method includes: loading an acquisition system to a seismic data set, picking up seismic first arrival traveltimes recorded by all shot gathers, and then performing refraction tomographic static correction, noise suppression, energy compensation, and deconvolution; processing the seismic data set after deconvolution by using an iterative residual static correction method and a high-accuracy velocity analysis method, to obtain a migration velocity model and a seismic data set after residual static correction; determining a common reflection point gather after muting and zero-offset gathers at different reflection points; calculating an amount of move-out correction for each common reflection point gather and a common reflection point gather after interferometric normal move-out correction; performing focus-stacking on the common reflection point gather after interferometric normal move-out correction, to obtain imaging results at different reflection points.

The disclosed technology provides solutions for identifying noise in seismic profile data sets. In some aspects, a process of the disclosed technology includes steps for receiving wellbore data including seismic measurements, processing the wellbore data to generate a seismic input image including visual representations of the one or more seismic measurements, and processing the seismic input image to identify a noise region in the seismic input image. Systems and machine-readable media are also provided.

A computer-implemented method includes the following. A frequency sweep using sweep parameters is emitted from a vibratory seismic source into geological layers. The sweep parameters include frequencies and modulation parameters for seismic waves. Signals are received from one or more sensors. The signals include seismic data acquisition information, including values identifying energy reflected back from boundaries where rock properties change. A determination is made regarding which of the reflected seismic waves are attenuated. The determination uses an integral transform and a thresholding algorithm for image segmentation. Optimum sweep parameters are determined based on the reflected seismic values that are attenuated and updated to compensate for local geology effects. The emitting, receiving, determining attenuation, determining optimum parameters, and updating are repeated until the received signals are determined to be satisfactory.