Abstract: The present disclosure provides a real-time correction method for an Oven Controlled Crystal (Xtal) Oscillator (OCXO) and an electromagnetic receiver. The real-time correction method for an OCXO includes: performing frequency multiplication on a reference clock signal to generate a first measurement signal and a second measurement signal; identifying a rising edge of each pulse per second on the basis of the first measurement signal to obtain a gate time T; obtaining a frequency of the second measurement signal according to the gate time T; and adjusting a frequency of the reference clock signal at least on the basis that an absolute value of a difference between two adjacent frequencies obtained of the second measurement signal is greater than a standard frequency difference.

Abstract: A method for a method for identifying a subsurface pore-filling fluid and/or lithology. A training set of field-acquired geophysical data and/or simulated geophysical data is provided to train a backpropagation-enabled process. The trained process is used on a field-acquired data set that is not part of the training set to infer presence of a subsurface pore-filling fluid and/or lithology.

Abstract: A method and a system for implementing the method are disclosed wherein the seismic input data and land acquisition 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, decomposes the cross-spread data into sparse common spread beams, then maps those sparse beams into common-spread depth domain, in order to finally stack them to construct the subsurface depth images. The common spread beam migration and processing have higher signal to noise ratio, as well as faster turn-around processing time, for the cross-spread land acquisition over the common-shot or common offset beam migration/processing. The common spread beam migration method and system disclosed, will eventually help illuminate and interpret the hydro-carbonate targets for the seismic processing.

Abstract: A method of generating a four dimensional seismic signal based on multiple sets of seismic data representing a subterranean formation. The method can include generating a tomographic velocity model based on a first set of raw seismic data and determining at least one Green's function based on the tomographic velocity model. The method can include generating a first image of a target region based on the first set of raw seismic data and the at least one Green's function. The method can include generating a second image of the target region based on a second set of raw seismic data and the at least one Green's function. The first and the second images can be compared, and a four-dimensional seismic signal can be determined based on the comparison.

Abstract: A simulator for light field displays. A high-performance simulator that can operate in real-time, allowing for VR-based evaluation of display designs. These capabilities allow for rapid exploration of display parameters (e.g. angular and hogel resolution, field of view, etc.), the visualization of how the angular spread of the rays that can affect quality and the evaluation of artifacts from light field processing. Additionally, the high-throughput nature of the simulation makes it amenable for use in the evaluation of light processing procedures such as those involved in light field rendering and compression contexts. The speed and ease with which one can explore light field display parameters makes this simulator the ideal tool for light field content design and evaluation.

Abstract: A method for use in seismic exploration includes: obtaining a diving wave illumination image of a subterranean region from a set of seismic data representative of the subterranean region using a selected acquisition geometry; clipping an inverse of the diving wave illumination image to a range of values; and performing a weighted full-waveform inversion. The weighted full-waveform inversion further includes: weighting a full-waveform inversion gradient with the clipped inverse of the diving wave illumination image; and performing the full-waveform inversion using the weighted gradient.

Abstract: A method and apparatus may include activating, by a network node, power of a global-positioning-system receiver or power of an active antenna of the global-positioning-system receiver. The apparatus uses the global-positioning-system receiver to perform synchronization of the apparatus. The method may include receiving at least one measurement, wherein the at least one measurement comprises real-time, predictive, or historic data. The method may also include determining a holdover duration based on the at least one measurement. The holdover duration corresponds to a length of time where the power of the global-positioning-system receiver or the power of the active antenna is to be turned off. The method may also include deactivating the power of the global-positioning-system receiver or the power of the active antenna for the holdover duration.

Abstract: An example system for noise removal in distributed acoustic sensing data may include a distributed acoustic sensing (DAS) data collection system and an information handling system coupled thereto. The information handling system may receive seismic information from the DAS data collection system. The seismic information may include seismic traces associated with a plurality of depths in the wellbore. The information handling system may also generate a noise pilot trace by stacking one or more of the seismic traces, and subtract the noise pilot trace from the seismic information received from the DAS data collection system.

Abstract: A method for evaluating anisotropy parameters using statistical moments calculates second and third central moments using reflectivity values associated with pairs of incidence and azimuth angles. The method further determines tangential and normal weaknesses for the location using the calculated second and third central moments for different incident angles. Linear and non-linear inversions of statistical moments are used to estimate the fracture weaknesses, anisotropic gradient (biased and unbiased), anellipticity variation and unambiguous orientation.

Abstract: Abstract Disclosed is a method for characterizing the evolution of a subsurface volume over time. The method comprises providing first and second surveys of the subsurface volume. Each survey comprises seismic data acquired by transmitting seismic signals into the subsurface volume and subsequently detecting some or all of the seismic signals after reflection within the subsurface. The first seismic data of the first survey corresponds to a first time and the second seismic data of the second survey corresponds to a second time. At least some of the first seismic data and the second seismic data is obtained with a non-zero offset.

Abstract: Seismic data recorded by subsurface seismic sensors placed in a borehole, such as an oil or gas well, are transformed via a process of upward wavefield propagation to pseudo-receivers at the surface of the earth. The seismic data thus transformed can be processed as though the data had been recorded by the pseudo-receivers at the surface rather than in the borehole where the data were actually recorded. This method accurately accounts for seismic source statics, anisotropy, and all velocity effects between the real receivers in the borehole and the pseudo-receivers at the surface of the earth.

Abstract: Various examples are provided for generalized internal multiple imaging (GIMI). In one example, among others, a method includes generating a higher order internal multiple image using a background Green's function and rendering the higher order internal multiple image for presentation. In another example, a system includes a computing device and a generalized internal multiple imaging (GIMI) application executable in the computing device. The GIMI application includes logic that generates a higher order internal multiple image using a background Green's function and logic that renders the higher order internal multiple image for display on a display device. In another example, a non-transitory computer readable medium has a program executable by processing circuitry that generates a higher order internal multiple image using a background Green's function and renders the higher order internal multiple image for display on a display device.

Abstract: A method, an apparatus and a computer-readable medium for processing seismic data are provided. The method includes selecting well-imaged areas of a sediment-to-salt interface, and performing (1) a dual-flood RTM with prismatic waves to identify new areas of the sediment-to-salt interface, and (2) one or more RTM to identify other new areas of the sediment-to-salt interface or of a salt-to-sediment interface.

Abstract: A method comprises obtaining vertical seismic profile (VSP) data using seismic sources positioned at corresponding shot locations at desired offsets from seismic receivers positioned in a borehole drilled through a formation. The method further comprises receiving seismic waves emanating from the seismic sources, processing the VSP data to determine vertical slowness of the formation, and analyzing an azimuthal anisotropy of the formation. This is performed by calculating modified total slowness of the formation using the vertical slowness and vertical polarization angle, calculating and applying a polar anisotropy correction to the modified total slowness to obtain a corrected value of the modified total slowness, and normalizing the corrected modified total slowness to a desired polarization angle.

Abstract: A method for processing seismic data. The method includes predicting seismic data according to an earth model representing seismic properties of subterranean formations in the earth, determining a difference between seismic data acquired from one or more seismic receivers and the predicted seismic data, projecting the difference into a model space in traveltime, and updating the earth model according to the projected difference. As a result, the updated earth model more accurately represents the seismic properties of subterranean formations in the earth.

Abstract: Described herein are implementations of various technologies for a method for configuring a seismic data acquisition network. A first message may be received from a first node of the seismic data acquisition network over a first direct communication link. The first message may comprise a first precision quality of a first reference clock to which the first node may be synchronized. A second message may be received from a second node of the seismic data acquisition network over a second direct communication link. The second message may comprise a second precision quality of a second reference clock to which the second node may be synchronized. One of the first precision quality and the second precision quality may be determined to have a higher precision quality. A real time clock may be synchronized to one of the first reference clock and second reference clock having the higher precision quality.

Abstract: A wireless seismic data acquisition unit with a wireless receiver providing access to a common remote time reference shared by a plurality of wireless seismic data acquisition units in a seismic system. The receiver is capable of replicating local version of remote time epoch to which a seismic sensor analog-to-digital converter is synchronized. The receiver is capable of replicating local version of remote common time reference for the purpose of time stamping local node events. The receiver is capable of being placed in a low power, non-operational state over periods of time during which the seismic data acquisition unit continues to record seismic data, thus conserving unit battery power. The system implements a method to correct the local time clock based on intermittent access to the common remote time reference. The method corrects the local time clock via a voltage controlled oscillator to account for environmentally induced timing errors.

Abstract: A technique includes determining a first difference between a time that a first network element of a seismic acquisition network receives a first frame pulse from a second network element of the seismic acquisition network and a time that the first network element transmits a second frame pulse to the second network element. The technique includes determining a second difference between a time that the second network element receives the second frame pulse and a time that the second network element transmits the first frame pulse. The technique includes determining a transmission delay between the first and second network elements based on the first and second time differences.

Abstract: Computing device and method for calculating time-shifts associated with travel-times of seismic waves emitted by a source and recorded by plural seismic detectors after reflection from a subsurface structure. The method includes receiving seismic data (d) that includes plural traces related to a subsurface, wherein the seismic data (d) is in a time-space domain; transforming with a processor the seismic data (d) from the time-space domain to a radon domain; picking linear events from the seismic data in the radon domain; calculating the time-shifts associated with the picked linear events; correcting the seismic data (d) based on the time-shifts to obtain new seismic data (d?); and computing an image of the subsurface based on the new seismic data (d?). The time-shifts are calculated per trace and per event.

Abstract: Computing device, software and method for identifying a source mechanism associated with a microseismic event taking place in a subsurface of the earth. The method includes receiving traces associated with a plurality of receivers located in a grid above the subsurface; dividing the grid in a set of sub-blocks, determining, for each sub-block, a corresponding summation element based on traces associated with the corresponding sub-block; identifying a predetermined number of patterns that are associated with plural source mechanisms; multiplying each summation element by a polarization coefficient according to a corresponding pattern; calculating for each pattern, a semblance function based on summation elements of the sub-blocks; and identifying the source mechanism of the microseismic event based on the semblance function.

Abstract: A walkaway VSP survey is carried out with receivers located in a borehole under a salt overhang. Redatuming of the multicomponent data to virtual sources in the borehole followed by vector Kirchhoff migration using a simple velocity model provides an accurate image of the salt face.

Abstract: Identification devices are known, e.g. in the form of labels to be attached by sewing or adhesive, monograms and the like, for the individualizing identification of items of clothing, shoes, shoe inserts or similar personal objects to be worn on a person's body. Whenever such identification devices are easy to read and to manufacture, they usually have relatively little recognition value. It is proposed to provide an identification device with, or to produce it in the form of, an image of a pressure-distribution pattern obtained by at least two-dimensional sampling of a pressure distribution between a part of the person's body and a substantially solid object.

Abstract: A method is disclosed for reflection time shift matching a first and a second set of seismic reflection data (10,30) comprising first and second seismic reflection traces (1,3) with series of generally corresponding seismic reflections (11,31). The second set of seismic data (30) comprises at least one laterally extending series (40) of new seismic events (4) not present in the first set of seismic data (10). Reflection time shifts (22) are calculated as required for matching seismic reflections (31) of the second reflection traces (3) of the second seismic reflection data (30) with corresponding seismic reflections (11) of the first reflection traces (1). The calculation of the time shifts (22) are made by calculating coefficients of basis function estimates such as Legendre polynomials in order to save calculation effort.

Abstract: The invention relates to a method of processing seismic data, the said seismic data comprising a gather of seismic traces organized according to one or several acquisition parameters, comprising the steps of: a) defining an equation for an RMO curve as a combination of elementary functions of the acquisition parameter(s), b) determining an RMO curve from the equation of step (a) as a combination of orthogonal elementary functions c) for a given time or at a given depth, determining the coefficients of the combination that optimize the semblance of traces along the RMO curve.

Abstract: A system for acquiring seismic data over sand dune surfaces is provided. The system includes a seismic wave generator for emitting a plurality of seismic signals into the Earth in an area covered by sand dunes. The system also includes a sand streamer for acquiring seismic data over the sand dune surfaces, such that the sand streamer includes a plurality of geophones. The plurality of geophones receive a plurality of wave signals transmitted from a subsurface corresponding to the sand dune surface, in response to emission of the plurality of seismic signals to the area of the sand dune surface by the seismic wave generator. Each geophone of the plurality of geophones is mounted on a panel wherein, one or more sides of the panel are coupled loosely to one or more rigid plates. The one or more rigid plates provide stability and mobility to assembly of panels and the plurality of geophones, thereby enabling the sand streamer to move efficiently over the surface of the sand dune.

Abstract: Various technologies for a seismic acquisition system, which may include an acquisition central system configured to determine a desired start time for a sweep cycle in one or more vibrators and a recorder source system controller in communication with the acquisition central system. The recorder source system controller may be configured to receive the desired start time from the acquisition central system. The seismic acquisition system may further include one or more vibrator units in communication with the recorder source system controller. Each vibrator unit may be configured to start a sweep cycle in a vibrator at the desired start time.

Abstract: Method for designing a converted mode (PS or SP) seismic survey to accomplish specified vertical and lateral resolution objectives at target depth. An equation (181) is provided for determining the minimum bandwidth required for a desired vertical resolution at a selected scattering angle, as a function of incident and reflected wave velocities, one of which is the P-wave velocity and the other is the S-wave velocity. A second equation (182) is provided for determining migration acceptance angle from the desired vertical and lateral resolutions. Source and receiver apertures may then be determined by ray tracing. Finally, a third equation (183) is provided for the maximum bin size to avoid aliasing, given the migration acceptance angle and a maximum frequency needed to achieve the bandwidth requirement. Source and receiver spacing may then be based on the maximum bin size.

Abstract: Three data subsets are obtained in three selected azimuthal directions from seismic data in heterogeneous, anisotropic media. Azimuthal velocities are determined for each of the data subsets. A linear system of equations in the three selected azimuthal directions and the three determined azimuthal velocities is solved for three independent parameters. An azimuthal time migration velocity function is constructed from the three solved independent parameters. A time migration traveltime function is constructed from the constructed azimuthal time migration velocity function.

Abstract: The invention relates to a method of processing seismic data, the said seismic data comprising a gather of seismic traces organised according to one or several acquisition parameters, comprising the steps of: a) defining an equation for an RMO curve as a combination of elementary functions of the acquisition parameter(s), b) determining an RMO curve from the equation of step (a) as a combination of orthogonal elementary functions c) for a given time or at a given depth, determining the coefficients of the combination that optimise the semblance of traces along the RMO curve.

Abstract: Time slices of seismic data are transformed from rectangular space-time domain to cylindrical space-time domain. 2-D seismic migration is performed on the transformed data for each radial direction. Slices of the migrated data are inverse transformed back to the rectangular space-time domain, generated migrated 3-D data for generally inhomogeneous media.

Abstract: A method for constructing a model representative of a heterogeneous medium from data expressed in different time scales with application to hydrocarbon characterization. The method first estimates sequentially, from the data expressed in each different time scale, parameters or physical quantities of the model, described for each different time scale. Second, a scale factor allowing conversion of a model described in a time scale into a model described in another time scale is determined. This determination is carried out by minimizing the dissimilarity between a parameter estimated in a time scale and this parameter estimated in the other time scale. Finally, estimation of a single model is performed, by taking simultaneously an account of the data expressed in the various time scales, and using the scale factor found previously for the time scale conversions.

Abstract: A method and a system for determining the position of a drill bit are presented. The method comprises determining positions of seismic wave detectors, recording seismic waves generated at the drill bit, identifying events at the drill bit, determining a plurality of relative positions of the drill bit, and determining, based at least partly on a starting position and a sum of the relative positions, an absolute position of the drill bit. The method further comprises determining a position of the drill bit at a second event in relation to a position of the drill bit at a first event, and determining a second seismic wave propagation velocity between the drill bit and at least one of the detectors, based at least partly on the determined position of the drill bit at the second event.

Abstract: A method is used to convert seismic data between bounding upper and lower surfaces in the time domain to the depth domain. An upper depth surface corresponding to the upper time surface is determined, either from well data or by time-depth conversion of the upper time surface. An interval velocity value is determined for each seismic sample between the bounding time surfaces from velocity data generated from well logs. The seismic times between the bounding time surfaces are then converted to the depth domain by adding the thickness of each seismic sample to the upper depth surface, wherein the thickness of each seismic sample is a function of the seismic sample rate and interval velocity value for each seismic sample. The seismic attribute values from the converted seismic data can be interpolated to a linear depth sampling.

Abstract: A wireless seismic data acquisition unit with a wireless receiver providing access to a common remote time reference shared by a plurality of wireless seismic data acquisition units in a seismic system. The receiver is capable of replicating local version of remote time epoch to which a seismic sensor analog-to-digital converter is synchronized. The receiver is capable of replicating local version of remote common time reference for the purpose of time stamping local node events. The receiver is capable of being placed in a low power, non-operational state over periods of time during which the seismic data acquisition unit continues to record seismic data, thus conserving unit battery power. The system implements a method to correct the local time clock based on intermittent access to the common remote time reference. The method corrects the local time clock via a voltage controlled oscillator to account for environmentally induced timing errors.

Abstract: A method and system for seismic data processing utilizes azimuthal variations in the velocity of seismic signals. The system and method utilizes a plurality of seismic energy sources that are located at known positions at the surface of the earth. The seismic energy sources generate seismic signals that propagate downward into the earth. Some of the seismic signals are reflected and diffracted by various sub-surface layers and are returned to the surface of the earth. The returned seismic signals are received by a plurality of receivers. The method includes the step of determining the distance from an energy source to an image point. A fast travel time of the seismic signal from the energy source to the image point is determined, and a slow travel time of the seismic signal from the energy source to the image point is determined. The azimuth angle between the energy source and the surface location of the image point is calculated.

Abstract: A method is disclosed for migrating seismic data which includes determining travel time of a compressional wave from a source location to a scatter point, taking into account ray bending. Travel time of a shear wave from the scatter point to a receiver location is determined, taking into account ray bending at the interfaces between subsurface strata. The determined travel times are then used to migrate the seismic data. In one embodiment, the travel times take account of vertically transversely isotropic media with a vertical symmetry axis.

Abstract: A method is disclosed for depth migrating seismic data. The method includes pre-stack time migrating the seismic data to form a stacked, time migrated image. The stacked, time migrated image is demigrated, and post-stack depth migration is then performed on the demigrated image. In some embodiments, the pre-stack time migration and the demigration account for ray bending in vertically transversely isotropic media.

Abstract: Three data subsets are obtained in three selected azimuthal directions from seismic data in heterogeneous, anisotropic media. Azimuthal velocities are determined for each of the data subsets. A linear system of equations in the three selected azimuthal directions and the three determined azimuthal velocities is solved for three independent parameters. An azimuthal time migration velocity function is constructed from the three solved independent parameters. A time migration traveltime function is constructed from the constructed azimuthal time migration velocity function.

Abstract: System and method for performing anisotropy corrections of post-imaging seismic data for a subsurface formation. The method may receive seismic data, preferably pre-stack seismic data comprising a plurality of traces, e.g., collected from a plurality of source and receiver locations. The seismic data may be imaged/migrated to produce imaged seismic data, which is organized into an arrangement that preserves aspects of the relative seismic propagation angle in the subsurface. One or more anisotropic parameters and corresponding corrections may be determined by analyzing the organized imaged seismic data. The determined parameters or corrections may be used to correct at least a subset of the imaged seismic data, thereby producing corrected seismic data which is useable in analyzing the formation. The corrected data may then optionally be stacked to produce a collection of corrected stacked traces, and/or analyzed as desired. The pre-stack data and/or the corrected seismic data may optionally be displayed.

Abstract: The present invention provides a method for analyzing traces collected along a plurality of adjacent sail lines in a marine seismic survey area. The method comprises selecting a plurality of trace groups, at least one trace in each group sharing a common midpoint with at least one trace from another group, determining an initial zero-offset travel time for each trace in the trace groups, and generating a plurality of updated zero-offset travel times and a plurality of time corrections for the trace groups using a pre-selected function of the initial zero-offset travel times.

Abstract: A method is disclosed for amplitude preserving Kirchhoff time migration. The method includes calculating estimates of the geometrical spreading terms using a constant velocity approximation. Takeoff and emergence angles are accurately calculated based on a model of velocity which varies with respect to travel time. An image can be calculated at at least one travel time using the estimated weights and calculated takeoff and emergence angles.

Abstract: A method is disclosed for processing seismic data. The method includes prestack depth migrating the seismic data to generate common image gathers using an initial velocity-depth model. Horizons in the migrated seismic data are selected. Residual migration velocity analysis in the depth-offset domain is performed with respect to each selected horizon, and the velocity-depth model is updated based on the residual migration velocity analysis.

Abstract: A method and apparatus for compensating acquired seismic data for the presence of dipping events are disclosed. The method includes migrating the acquired, unstacked seismic data; and spatially mapping the migrated seismic data to correct their respective offsets while maintaining the angle of incidence to a dipping event. The method may be performed by a programmed computing device or encoded as instructions for a computing device on a program storage medium.

Abstract: The present invention provides methods to be used in seismic data processing to address problems encountered during data acquisition. The present invention provides a multi-step process to reduce aliasing of seismic data along time slices.

Abstract: The invention comprises a system for processing seismic data to estimate time shift resulting from velocity anisotropy in the earth's subsurface. A gather of seismic data traces is formed and selected seismic data traces included in said gather within selected time windows are cross-correlated to estimate the time shift in the seismic data traces included in said gather resulting from velocity anisotropy in the earth's subsurface.

Abstract: Seismic imaging apparatus for receiving data propagated through sub-surface structure from a seismic source to at least one seismic receiver and forming an image therefrom, the apparatus comprising: an imager for forming an initial image from said data including initial locations of seismic features indicated in said data, a migrator, associated with said imager, for carrying out seismic migration over at least two layers or depth levels to provide corrections to said initial locations, said migrator comprising a krylov space expander for carrying out a krylov space expansion of the exponent of a square root operator, the operator being for defining a wave propagation between respective layers, and a corrector, for using said corrections with said initial locations to form a seismic image indicating said features.

Abstract: The present invention relates to a method for estimating the position and trajectory of a drill during drilling of boreholes in rock. The method comprising the steps of determining the starting position of the drill bit and recording the received transient seismic waves generated by the drill on impact, and estimating the difference in arrival time between events. From these, the relative distances, between the positions of the drill bit at different events are calculated and from these the present position is calculated.

Abstract: Seismic imaging apparatus for receiving data propagated through sub-surface structure from a seismic source to at least one seismic receiver and forming an image therefrom, the apparatus comprising: an imager for forming an initial image from said data including initial locations of seismic features indicated in said data, a migrator, associated with said imager, for carrying out seismic migration over at least two layers or depth levels to provide corrections to said initial locations, said migrator comprising a krylov space expander for carrying out a krylov space expansion of the exponent of a square root operator, the operator being for defining a wave propagation between respective layers, and a corrector, for using said corrections with said initial locations to form a seismic image indicating said features.

Abstract: A method of performing normal moveout (NMO) correction and stacking of a common-midpoint (CMP) gather of seismic traces in a manner that avoids NMO stretch is disclosed. A CMP gather without NMO correction is modeled as the sum of a series of short overlapping time intervals whose center times follow the NMO curve as it changes with offset. The sample values contained in these intervals are solved simultaneously by performing a statistical fit to the CMP gather based on this model. A CMP stacked trace is formed by summing these intervals at their zero-offset positions at each time sample.

Abstract: A method of calculating a throw volume corresponding to a seismic data volume. A range of time shifts and a search direction for the seismic data volume are selected. A data location separation and a vertical time window are also selected. A cross-correlation is calculated between data values corresponding to first and second data locations separated by the data location separation and symmetrically located in the search direction on each side of a target data location. The cross-correlation is calculated throughout the vertical time window for each time shift in the range of time shifts. The time shift corresponding to the maximum calculated cross-correlation is stored in the throw volume.