Abstract: Monitoring and diagnosing completion during hydraulic fracturing operations provides insights into the fracture geometry, inter-well frac hits and connectivity. Conventional monitoring methods (microseismic, borehole gauges, tracers, etc.) can provide a range of information about the stimulated rock volume but may often be limited in detail or clouded by uncertainty. Utilization of DAS as a fracture monitoring tool is growing, however most of the applications have been limited to acoustic frequency bands of the DAS recorded signal. In this paper, we demonstrate some examples of using the low-frequency band of Distributed Acoustic Sensing (DAS) signal to constrain hydraulic fracture geometry. DAS data were acquired in both offset horizontal and vertical monitor wells. In horizontal wells, DAS data records formation strain perturbation due to fracture propagation. Events like fracture opening and closing, stress shadow creation and relaxation, ball seat and plug isolation can be clearly identified.

Abstract: Methods and apparatus are described for reducing noise in measurements made by one or more pressure sensors disposed in a cable having a generally longitudinal axis. Estimated axial vibration noise at a location along the cable is determined based at least in part on measurements from one or more motion sensors disposed along the cable. The estimated axial vibration noise is subtracted from pressure sensor measurements corresponding to the location. The result is noise-attenuated pressure sensor measurements corresponding to the location.

Abstract: A method for 2D seismic data acquisition includes determining source-point seismic survey positions for a combined deep profile seismic data acquisition with a shallow profile seismic data acquisition wherein the source-point positions are based on non-uniform optimal sampling. A seismic data set is acquired with a first set of air-guns optimized for a deep-data seismic profile and the data set is acquired with a second set of air-guns optimized for a shallow-data seismic profile. The data are de-blended to obtain a deep 2D seismic dataset and a shallow 2D seismic dataset.

Abstract: Marine survey source route configuration can include towing, via a first marine survey vessel, streamers at a first average speed and at an average velocity along a first survey route. A second marine survey vessel can tow a source at a second average speed that is greater than the first average speed along a second survey route that periodically passes over the first survey route and at the average velocity in a direction of the first survey route.

Abstract: The disclosure provides systems and methods to enhance pre-stack data for seismic data analysis by: sorting the reflection seismic data acquired from cross-spread gathers into sets of data sections; performing data enhancement on the sets of data sections to generate enhanced traces by: (i) applying forward normal-moveout (NMO) corrections such that arrival times of primary reflection events become more flat, (ii) estimating beamforming parameters including a nonlinear traveltime surface and a summation aperture, (iii) generating enhanced traces that combine contributions from original traces in the sets of data sections, and (iv) applying inverse NMO corrections to the enhanced traces such that temporal rearrangements due to the forward NMO corrections are undone.

Abstract: Techniques are disclosed relating to performing marine surveys with non-uniform spacing of survey elements in a cross-line direction. This may include, for example, performing a survey pass in a multi-pass survey by towing a plurality of sources and sensors in a towing pattern with non-uniform spacing between adjacent ones of the sources. In some embodiments, the non-uniform spacing between adjacent ones of the sources is determined based on a common mid-point (CMP) spacing parameter for the survey pass in the cross-line direction. The spacing parameter may relate, for example, to difference in average CMP spacing for different parts of the survey spread, variance in CMP spacing, and/or width of the survey spread for which a threshold CMP spacing distance is satisfied. In various embodiments, the disclosed techniques may improve survey resolution and/or accuracy and may require a smaller number of survey passes and/or a reduced amount of survey equipment relative to traditional techniques.

Abstract: A system for seismic imaging of a subterranean geological formation, the system includes a receiver configured to obtain seismic data comprising a data volume representing a post-stacked image. The system includes a filtering module configured to: apply frequency-wavenumber (F-K) filter to the data volume extract a negative-dip structure image and apply the frequency-wavenumber (F-K) filter to the data volume extract a positive-dip structure image. The system includes a diffraction rendering module configured to: multiply the positive-dip structure image with the negative-dip structure image and generate a diffraction-enhanced seismic image representing a geological formation of the data volume.

Abstract: Methods and seismic shot generation and data collection systems configured to determine a monotonically increased velocity v*(z) from a monotonically increased velocity model by requiring the monotonically increased velocity v*(z) to be nearest to a refraction velocity v(z) determined for an estimated depth z and to be characterized by a positive slope such that the refraction velocity v(z) increases with depth, and to generate a subsurface image based on the estimated depth z and the determined monotonically increased velocity v*(z).

Abstract: A method of performing notch compensation and a system to perform notch compensation for a first seismic streamer are described. The method includes disposing the first seismic streamer at a first depth, where the seismic streamer includes a first set of sensors to receive reflections resulting from a seismic source, the reflections indicating a notch at a frequency. The method also includes disposing a second seismic streamer at a second depth, the second depth being less than the first depth and the second seismic streamer including a second set of sensors to receive reflections resulting from the seismic source. The method further includes processing the reflections received by the first set of sensors and the second set of sensors together to derive the match filter, and applying the match filter to the reflections received by the first set of sensors of the first seismic streamer to compensate for the notch.

Abstract: A method for determining seismic sensor depths in a body of water includes accepting as input to a computer measurements of seismic signals made by a plurality of seismic sensors disposed in a body of water. A depth increment and a range of sensor depths for correlation of signals from each of the plurality of seismic sensors is defined. In the computer, the input seismic measurements are extrapolated to each depth increment in the range. A depth of each seismic sensor is determined by correlating the seismic signal measurements with depth-extrapolated measurements of the seismic signal measurements.

Abstract: 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.

Abstract: Survey design for data acquisition using marine non-impulsive sources can include operating a first marine non-impulsive source at over a first frequency range for a first sweep length and operating a second marine non-impulsive source over a second frequency range for a second sweep length. The first sweep length can be based on available geological information of a subsurface location that is a target of a marine seismic survey, an intended speed of a marine survey vessel, and the first frequency range. The second sweep length can be based on the available geological information, the intended speed, and the second frequency range.

Abstract: Systems and methods of near surface imaging and hazard detection with increased receiver spacing are provided. The system includes: a first string of one or more acoustic sources, a second string of one or more acoustic sources opposite the first string, a first one or more hydrophones mounted within a predetermined distance of the first string, and a second one or more hydrophones mounted within the predetermined distance of the second string. The first one or more hydrophones records an acoustic shot generated from the first string. The second one or more hydrophones records the acoustic shot and acoustic reflections corresponding to the acoustic shot. The system generates an image from the recorded acoustic shot and the acoustic reflections.

Abstract: Managing movement of data packets along a geophysical sensor cable. At least some embodiments include a geophysical sensor cable section having an internal volume within which geophysical sensors are disposed at spaced apart locations. A digitizer is disposed within the internal volume and is communicatively coupled to sensors. A telemetry unit within the internal volume is communicatively coupled to the digitizer. The telemetry unit may comprise multiple forward ports, multiple aft ports and a controller communicatively coupled to the forward ports, the aft ports, and the digitizer. The controller may be configured to: relay downstream-directed packets received on an active forward port through all aft ports; gather sensor data from the digitizer and send the sensor data as upstream-directed packets through the active forward port; and relay any upstream-directed packets received on aft ports through the active forward port.

Abstract: A method for seismic data processing can include obtaining seismic data acquired based upon trigger times and not based upon positions of triggered source elements. The seismic data can include near-continuously recorded seismic data in split records. The split records can be spliced together into a single near-continuous record to produce a trace with seismic data from a single acquired line. The seismic data can be processed by performing a spatial shift for each of a number of time samples to correct for motion of a number of seismic receivers.

Abstract: Methods, systems, and computer-readable medium to perform operations including obtaining, for a plurality of traces, seismic signal amplitude data associated with a plurality of sources and receivers; determining that the signal amplitude data includes at least a receiver key and a source key; in response to the determining, generating a receiver group key and a source group key; assigning a respective weight to each of the receiver key, the source key, the receiver group key, and the source group key; and generating surface-consistent amplitude data using the constrained linear system of equations and each scaling factor of the weighted-receiver key, the weighted-source key, the weighted-receiver group key, and the weighted-source group key.

Abstract: A method of performing a seismic survey including: deploying nodal seismic sensors at positions in a survey region; activating a plurality of seismic sources; and using the nodal seismic sensors to record seismic signals generated in response to the activation of the plurality of signals.

Abstract: A security system may include a normally open relay between an external network connection and at least one internal network connection, a network controller, and a microcontroller. The network controller may be configured to monitor for malicious activity on an external network accessible through the external network connection. The microcontroller may be configured to cause the normally open relay to temporarily close in response to the network controller failing to detect the malicious activity for a predetermined amount of time and cause the normally open relay to remain open and generate an alert in response to the network controller detecting the malicious activity.

Abstract: A method of reducing surface-scattered noise includes receiving seismic data associated with a marine region, where the marine region includes an ocean bottom, a first zone including water above the ocean bottom, and a second zone including earth subsurface layers below the ocean bottom, and the received seismic data includes signals reflected from the earth subsurface layers and surface-scattered noise reflected from the ocean bottom and an ocean surface; determining a water velocity for the first zone; determining bathymetric values of the ocean bottom; based on the determined water velocity and the bathymetric values, determining a velocity model for the marine region; based on the determined velocity model and wavelet functions of seismic source signals, calculating the surface-scattered noise by solving a wave equation; and determining the signals reflected from the earth subsurface layers by subtracting the calculated surface-scattered noise from the received seismic data.

Abstract: A sample and hold circuit with long hold time. A sample and hold circuit includes an amplifier, a capacitor, a switch, and a sampling network. The capacitor includes a first terminal coupled to an inverting input of the amplifier. The switch includes a first terminal that is coupled to an output of the amplifier, and a second terminal that is coupled to the inverting input of the amplifier. The sampling network is coupled to a non-inverting input of the amplifier.

Abstract: A method of generating geophysical data using at least one source. The method may include the steps of generating a geophysical wavefield with a varying signature using at least one source, wherein the signature is varied in a periodic pattern.

Abstract: A high performance attitude determination system, including a global navigation satellite system (GNSS) receiver, the receiver including a first radio-frequency front-end (RF1) connected to a main antenna; a second radio-frequency front-end (RF2) connected to an auxiliary antenna; and a digital section connected to both RF1 and RF2. The digital section (i) generates a first set of GNSS raw measurements based on signals received from RF1; (ii) generates a second set of GNSS raw measurements based on signals received from RF2; (iii) computes a spatial attitude of a baseline between main and auxiliary antennas, using the first and the second sets of GNSS raw measurements, and based on carrier phase integer ambiguity resolution; (iv) continues updating the spatial attitude using the first and the second sets of GNSS raw measurements without carrier phase integer ambiguity resolution, and using fractional carrier phases. Optionally, RF1 and RF2 use a common clock.

Abstract: Embodiments of the present disclosure include one or more of a method, computing device, computer-readable medium, and system for statistical line and edge detection and/or enhancement. An example embodiment of the present disclosure may include a method that includes identifying a plurality of data values related to a first object defined by a first plurality of points within the volume, wherein the first object intersects a second object defined by a second plurality of points within the volume; calculating a statistical significance statistic related to the second object; interpolating a P-value related to the statistical significance statistic; and determining a significant P-value taken over the second object, wherein the significant P-value comprises a minimum P-value that provides a maximum negative log(P(statistical significance statistic)).

Abstract: A sample and hold circuit with long hold time. A sample and hold circuit includes an amplifier, a capacitor, a switch, and a sampling network. The capacitor includes a first terminal coupled to an inverting input of the amplifier. The switch includes a first terminal that is coupled to an output of the amplifier, and a second terminal that is coupled to the inverting input of the amplifier. The sampling network is coupled to a non-inverting input of the amplifier.

Abstract: A method for rotating recorded seismic data.

Abstract: Embodiments relate to a sensor cable that may be reconfigurable to have various combinations of seismic sensors. An apparatus may comprise a sensor cable and seismic sensors distributed throughout a volume of the sensor cable and along all three axes of the sensor cable, wherein the seismic sensors are assigned to sampling groups that are reconfigurable and not hardwired.

Abstract: A radar device employs a configuration provided with: a receiver which, in operation, receives one or more radar transmission signals transmitted from another radar device, in an interference measurement segment in which transmission of a radar transmission signal from the radar device is stopped; A/D conversion circuitry which, in operation, converts the one or more radar transmission signals from the other radar device received by the receiver from one or more analog signals into one or more digital signals; and an interference detection circuitry which, in operation, performs a correlation calculation between each of one or more discrete samples that is the one or more digital signals and a prescribed coefficient sequence to detect one or more prescribed frequency components included in the one or more digital signals, as one or more interference signal components.

Abstract: Source element of a source subarray can be individually actuated according to an actuation sequence. The actuation sequence can be at least partially based on a relative position of each of the source elements within a particular geometry of the source subarray with respect to a previously actuated source element and a towing velocity of the source subarray.

Abstract: A method is provided of processing data representing a physical system, the method comprising: providing (P2) input data representing differences in the physical system between a first state and a second state of the physical system; and inverting (P5) the input data, or data derived therefrom, in accordance with a parameterized model (PI) of the physical system to obtain differences in the parameters of the model between the first state and the second state, with parameters of the model representing properties of the physical system; wherein the inverting step is performed (P3 to P6) for a plurality of different perturbations (P4) of the parameterized model and/or of the data to obtain a plurality of sets of differences in the parameters of the model; and wherein a statistical analysis (P7) of the plurality of sets of differences is performed to obtain statistical characteristics of the differences in the parameters of the model.

Abstract: Autonomous water column profilers are deployed over an area and each independently samples attributes in its water column to provide a three dimensional array of data points. The profilers are negatively buoyant and autonomously assume positive buoyancy; for example, by jettisoning a ballast weight, preferably collecting and storing measurements at programmed times or depths when descending and again when ascending. The devices can be recovered for accessing onboard memories or a wireless communications system can be employed for uploading data to a transponder. The profilers can be deployed from marine vessels, aircraft, or remotely operated vehicles and are advantageous for monitoring oil well leaks or spills, assessing dispersant programs when ameliorating released oil, for sensing natural seeps, and similar applications.

Abstract: Methods and Systems for extrapolating wavefields while avoiding disruptions due to spatial aliasing are disclosed. Pressure wavefields measured with pressure sensors and vertical and horizontal velocity wavefields measured with three-axial motions sensors may be spatially aliased in at least one horizontal direction. The pressure wavefield and/or the vertical velocity wavefield are decomposed into one of an up-going wavefield and a down-going wavefield. The up-going or down-going wavefield is extrapolated using an extrapolator that depends on components of a slowness vector. In order to avoid disruptions in the extrapolated wavefield due to spatial aliasing, the components of the slowness vector are calculated from the measured pressure wavefield and the two horizontal velocity wavefields.

Abstract: Methods and apparatuses for processing marine seismic data with a process of combined deghosting and sparse ?-p transformation. The process is formulated as an optimization problem. The optimization problem has an objective function that is a weighted sum of two norms: one norm is an Lp norm of the differences between the modeled data and acquired survey wherein the modeled data are derived from a model and a set of adaptive filters; the other norm is an Lq norm of the model; and the optimization variables and solutions are the coefficients of the model and coefficients of the adaptive filters.

Abstract: A method, including: storing, in a computer storage device, geophysical seismic data that has been separated into a multiple-free component and a multiple contaminated component; performing, with a processor, a first full wavefield inversion process on the multiple-free component of the seismic data, wherein a first subsurface physical property model is generated; determining, with a processor, an extended target reflectivity, wherein the extended target reflectivity includes a reflectivity for each of a plurality of shots; separately performing, with a processor, a second full wavefield inversion process with the multiple contaminated component of the seismic data for each of the plurality of shots using the reflectivity corresponding to each of the plurality of shots, wherein a second subsurface physical property model is generated; and generating, with a processor, multiple-free final subsurface physical property model by combining the first subsurface physical property model and the second subsurface phys

Abstract: A method for estimation of water properties from seismic data can include determining a number of travel times for at least one event based, at least in part, on predefined values for a plurality of water properties, determining an alignment of data values for each of the number of travel times determined for the at least one event, and determining an estimation of a plurality of undetermined water property values based, at least in part, on the alignment of the data values for each of the number of travel times producing a high quantitative measure of a coherence value.

Abstract: A method, apparatus, and program product model stress characteristics of a subsurface formation based at least in part on acoustic data and image data associated with the subsurface formation. The acoustic data is analyzed to determine acoustic based stress values, and the image data is analyzed to determine image based stress values. The acoustic based stress values and the image based stress values are integrated to generate an integrated stress profile that includes one or more modeled stress characteristics of the subsurface volume.

Abstract: A method of more accurate phase encoding of phase offset vibrators used in simultaneous-multiple-sourcing 3D seismic mapping. The method measures the actual input energy and the proxy energy thereby determining a bulk error and a frequency-dependent error, both to be applied to correct the proxy energy. The corrected proxy energy is then used to perform actual seismic survey, and the inversion is then performed using the corrected proxy energy to source separate each vibe where the error is minimized.

Abstract: A technique includes receiving first data acquired by at least a particle motion gradient sensor or a rotation sensor of a streamer that is subject to vibration due to towing of the streamer; and receiving second data acquired by at least one particle motion sensor of the streamer and being indicative of particle motion and vibration noise. The technique includes processing the second data in a processor-based machine to, based at least in part on the first data, attenuate the vibration noise indicated by the second data to generate third data indicative of the particle motion.

Abstract: Noise can be attenuated in marine seismic data from a marine seismic survey. A first near-continuous measurement of a wavefield and a second near-continuous measurement of the wavefield recorded from a marine seismic survey can be equalized, a coherent portion of the equalized second near-continuous measurement can be collapsed, and a noise model can be derived. The noise model can be subtracted from the second near-continuous measurement.

Abstract: A method can include receiving data in a data domain where a first portion of the data domain includes a signal to noise ratio that exceeds a signal to noise ratio in a second portion of the data domain; generating a model; in a transform domain, based at least in part on the model, filtering at least a portion of the data in the second portion of the data domain; and, based at least in part on the filtering, outputting noise attenuated data for at least a portion of the data in the second portion of the data domain.

Abstract: Methods are disclosed for sensing acoustic waves in a medium. One example includes a first elongated member, a first motion sensor sensitive to vibrations of the first elongated member, a second motion sensor spaced apart from the first motion sensor and also sensitive to vibrations of the first elongated member, and a first vibration source operably coupled to the first elongated member and configured to vibrate the first elongated member.

Abstract: Various technologies described herein are directed to a method that includes deploying a plurality of wave gliders in a seismic survey area, where the plurality of wave gliders has one or more seismic sensors coupled thereto for acquiring seismic data. The method may also include deploying at least one source vessel in the seismic survey area, where the at least one source vessel has one or more sources coupled thereto and a central communication unit disposed thereon. The method may then include positioning the plurality of wave gliders according to an initial navigation plan. The method may further include monitoring a relative position of a respective wave glider in the plurality of wave gliders with respect to other wave gliders in the plurality of wave gliders and with respect to the at least one source vessel.

Abstract: A computing system and method for mitigating, in a first seismic survey, cross-talk generated by a second seismic survey. The method includes performing the first seismic survey with a first survey seismic source driven by a first survey pilot sweep, performing the second seismic survey with a second survey seismic source, simultaneously with the first seismic survey, recording with first survey seismic sensors (i) first survey seismic signals that originate from the first survey seismic source and (ii) second survey seismic signals that originate from the second survey seismic source, selecting another first survey pilot sweep, which has less cross-correlation noise with the second survey seismic signals than the first survey pilot sweep, and continuing the first seismic survey with the another first survey pilot sweep.

Abstract: Sensors used in mapping strata beneath a marine body are described, such as used in a flexible towed array. A first sensor is a motion sensor including a conductive liquid in a chamber between a rigid tube and a piezoelectric motion film circumferentially wrapped about the tube. A second sensor is a traditional acoustic sensor or a novel acoustic sensor using a piezoelectric sensor mounted with a thin film separation layer of flexible microspheres on a rigid substrate. Additional non-acoustic sensors are optionally mounted on the rigid substrate for generation of output used to reduce noise observed by the acoustic sensors. Combinations of acoustic, non-acoustic, and motion sensors co-located in rigid streamer housing sections are provided.

Abstract: Method for inverting, in the frequency domain (42), controlled source electromagnetic survey data (41) acquired using a time-division compound waveform made up of sub-sequences of different base waveforms, for example square waves of different frequencies. A windowed Fourier decomposition method is used, with the window size and shape designed in consideration of the sub-sequences. The window length may be twice the length of the compound waveform, or more. Alternatively the window length may be comparable to the sub-sequence length, or slightly less. Window shapes include cos2, rectangular, and triangular. The method addresses the problem of unknown arrival times for each sub-sequence, and also transition transients that occur between sub-sequences.

Abstract: A method for obtaining zero-offset and near zero offset seismic data from a marine survey, with separation of direct arrival information and reflectivity information, the method including: modeling a direct arrival estimate at a passive near-field hydrophone array by using a notional source separation on active near-field hydrophone data; generating reflection data for the passive near-field hydrophone array by subtraction of the modeled direct wave from data recorded by the passive near-field hydrophone array; generating near zero-offset reflectivity traces by stacking the reflection data for the passive near-field hydrophone array on a string-by-string basis or on a combination of strings basis.

Abstract: 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.

Abstract: Systems and methods are provided for a magneto-seismic exploration of a subsurface region. An electromagnetic source may transmit time-varying electromagnetic field into the subsurface region, in the presence of a static or time-varying magnetic field, such that a component of the electric field associated with the time-varying electromagnetic field is substantially parallel to an interface between two subsurface formations in the subsurface region, wherein the electric field interacts with the static or time-varying magnetic field and creates a Lorentz force in each of the subsurface formations. One or more seismic receivers may detect a seismic signal generated by a Lorentz force change at the interface between the two subsurface formations. A computer system may be programmed to process and present the detected seismic signal.

Abstract: A method of performing notch compensation and a system to perform notch compensation for a first seismic streamer are described. The method includes disposing the first seismic streamer at a first depth, where the seismic streamer includes a first set of sensors to receive reflections resulting from a seismic source, the reflections indicating a notch at a frequency. The method also includes disposing a second seismic streamer at a second depth, the second depth being less than the first depth and the second seismic streamer including a second set of sensors to receive reflections resulting from the seismic source. The method further includes processing the reflections received by the first set of sensors and the second set of sensors together to derive the match filter, and applying the match filter to the reflections received by the first set of sensors of the first seismic streamer to compensate for the notch.

Abstract: A system and method for performing seismic exploration with multiple acquisition systems is disclosed. The method includes configuring a first seismic source located outside of an exclusion zone and configuring a second seismic source located inside of the exclusion zone. The method further includes obtaining a first seismic dataset corresponding to a first seismic signal emitted by the first seismic source and obtaining a second seismic dataset corresponding to a second seismic signal emitted by the second seismic source. The method further includes combining the first and second datasets to create a complete dataset covering a survey area and creating a seismic image of a subsurface of the survey area.

Abstract: Methods and systems that attenuate noise in seismic data. In one aspect, noise attenuation methods iteratively generate a low-speed noise model of low-speed noise recorded in the seismic data. The seismic data is arranged into a sparse seismic-data matrix. Low-speed noise refers to noise that propagates at speeds less the speed of sound in water. The low-speed noise model includes the low-speed noise and includes interpolated low-speed noise that approximates portions of the low-speed noise typically affected by spatial aliasing and streamer surface irregularities. The low-speed noise model may be subtracted from the sparse seismic-data matrix to obtain a noise-attenuated sparse seismic-data matrix.