To mitigate zigzag noise and increase the quality of data provided from DAS VSP in wells with significant vertical sections, zigzag noise characteristics are identified and quantified. The zigzag noise properties can be extracted from an analysis of an autocorrelation of DAS VSP traces. The zigzag noise has a characteristic time period or repeat time delay that is the time period for the noise to propagate along the wireline through a zone of the wellbore with poor acoustic coupling between the fiber optic cable and formation. This period can be identified from analysis of the autocorrelation referred to herein as a crosswise lag summation function. The crosswise lag summation function identifies groups of DAS data traces containing zigzag noise and outputs zigzag noise periodicity for each group of traces. Once it has been identified, the zigzag noise can be removed from the VSP data and improve formation evaluation.

A device may include a processor that may recover the signals misallocated in the deblending process of seismic data acquired with simultaneous sources. The processor may update the primary signal estimate based at least in part on a separation operation that separates coherence signals from noise signals in an output associated with the residual determined to be remaining energy for separation. The processor may be incorporated into the iterative primary signal estimate of the deblending process or be applied towards preexisting deblending output. In response to satisfying an end condition, the processor may transmit a deblended output that includes the weak coherence signals recovered from the misallocation or error in the primary signal estimate. The processor may also transmit the deblended output for use in generating a seismic image. The seismic image may represent hydrocarbons in a subsurface region of Earth or subsurface drilling hazards.

The invention notably relates to a computer-implemented method for processing a 4D seismic signal relative to a subsoil, the subsoil including a zone subject to extraction and/or injection, the method comprising: providing the 4D seismic signal; identifying a part of the 4D seismic signal corresponding to a zone of the subsoil distinct from the zone subject to extraction and/or injection; determining a noise model of the 4D seismic signal based on the identified part of the 4D seismic signal; and processing the 4D seismic signal based on the noise model. This improves the field of 4D seismic data processing.

A method for expediently processing and inverting elastic wave data to reduce the amount of data and to determine a physical properties model of the material medium and a source properties model. The data are processed to generate waveforms containing the phase difference between compressional- and shear-wave arrivals using auto-correlation, cross-correlation, or deconvolution of said data sensed at each of an arrangement of sensors, whereby said lengthy elastic wave data records are reduced substantially in time. Said waveform data are thereafter inverted using waveform inversion by modifying the source term in the equation of motion, wherein the source term is mathematically expressed as a product of time-independent source properties volume defined at every location in space within said material medium and a space-independent source-time function, whereby no prior knowledge of the number of sources, spatial distribution of source location, source amplitude, or source focal mechanism is needed.

Techniques are disclosed relating to machine learning in the context of noise filters for sensor data, e.g., as produced by geophysical surveys. In some embodiments, one or more filters are applied to sensor data, such a harsh filter determined to cause a threshold level of distortion in measured reflections, a mild filter determined to leave a threshold level of remaining noise signals, or an acceptable filter. In some embodiments, the system trains a machine learning classifier based on outputs of the filtering procedures and uses the classifier to determine whether other filtered sensor data from the same survey exhibits acceptable filtering. This may improve accuracy or performance in detecting unacceptable filtering, in some embodiments.

Rock reservoir structure characterization method comprises: acquiring a three-dimensional seismic data volume of a rock reservoir to be characterized; performing a transformation on all the intrinsic mode function components obtained through decomposition to obtain time-frequency spectrum of each intrinsic mode function component, and adding the time-frequency spectrums of all the components to obtain the time-frequency spectrums of the seismic data; performing cross-correlation between each of the time-frequency components of the near-well seismic traces and the synthetic seismic trace obtained by logging data of the same well, and screening out a sensitive component with the highest correlation degree as an input feature, and performing fuzzy C-means clustering and spatial smoothing on the sensitive component with the highest correlation degree to obtain a seismic facies with set standard division; and depicting the rock reservoir according to the seismic facies divided by the set standard.

The invention relates to a method for monitoring the physical state of a longitudinal element (IO) of a railway-type rail, the method having a step of detecting mechanical waves moving along the longitudinal element (IO), in particular due to the passing of a train, by means of an array of mechanical wave sensors placed along and in contact with the longitudinal element, the array having at least one first pair (A) of sensors each positioned at one end of a first portion (IOa) of the longitudinal element (IO), and a step of processing the signals emitted by the sensors in the array of sensors, the processing step having the determination of at least one first interfered signal determined from signals provided by the sensors in the first pair (A) of sensors over a first predetermined period of time.

Methods, systems, and computer readable media for gridding of subsurface salt structures include determining a predetermined area lacks three dimensional seismic coverage, generating a two dimensional seismic top salt interpretation for the predetermined area, generating a bathymetry elevation of the predetermined area, determining that at least one two dimensional seismic line intersects a bathymetric feature of interest, and determining a correlation coefficient between the two dimensional seismic top salt interpretation and the bathymetry elevation. The method may further include determining the correlation coefficient is greater than a predetermined threshold value, and applying the bathymetry elevation as an additional control for gridding top of the subsurface salt structure. The step of gridding the top of the subsurface salt structure may further include applying at least one of kriging with external drift (KED), polygon-based approaches, regression-kriging, and other geostatistical methods.

Methods and systems to separate seismic data associated with impulsive and non-impulsive sources are described. The impulsive and non-impulsive sources may be towed through a body of water by separate survey vessels. Receivers of one or more streamers towed through the body of water above a subterranean formation generate seismic data that represents a reflected wavefield produced by the subterranean formation in response to separate source wavefields generated by simultaneous activation of the impulsive source and the non-impulsive source. Methods and systems include separating the seismic data into impulsive source seismic data associated with the impulsive source and non-impulsive source seismic data associated with the non-impulsive.

An initial gather of blended seismic signals induced in a common seismic receiver by a plurality of actual sources grouped in actual source groups is provided. Each actual source group has a linear source geometry that is the same for each actual source group. The plurality of sources in each actual source group is fired according to a pre-selected firing sequence that is the same for each actual source group. Actual shot records are created from the blended signals, and fictive shot records are created of seismic signals for fictive source groups that each have the same source geometry as the actual source groups, by interpolation of the actual shot records. Single source shot records of single source signals are separated by discrete deconvolution of the actual shot records and the fictive shot records. The output includes a seismic gather comprising a plurality of the single source shot records.