Abstract: A technique includes obtaining first data indicative of seismic measurements acquired by seismic sensors of a first set of towed streamers and obtaining second data indicative of seismic measurements acquired by seismic sensors of a second set of towed streamers. The second set of towed streamers is towed at a deeper depth than the first set of towed streamers. The technique includes interpolating seismic measurements based on the first and second data. The interpolation includes assigning more weight to the second data than to the first data for lower frequencies of the interpolated seismic measurements.

Abstract: Methods and apparatus for determining an accurate differential transfer function (DTF) between two closely spaced hydrophones in a dual-hydrophone configuration such that the wavefield may be properly separated into up- and down-going components are provided. The methods disclosed herein are based on the premise that the cross-correlation at a lag of zero between up- and down-going wavefields should be at a minimum for perfectly matched hydrophones. Thus, any suitable global optimization technique may be utilized to determine an accurate DTF where the zero-lag cross-correlation between up- and down-going energy is at a minimum after multiplying a particular hydrophone spectrum of the pair (depending on how the DTF was defined) with a possible DTF suggested by the global optimization technique.

Abstract: A technique includes obtaining seismic data, which was acquired during a seismic survey in seawater. The technique includes based on the seismic data, determining a conductivity of the seawater and processing data obtained from an electromagnetics-based survey based on the determined conductivity.

Abstract: Seismic data from towed marine streamers are sorted into two-dimensional common midpoint gathers of traces. The gathered traces are ordered by offset. The offset distribution of the ordered traces is regularized. The source and receiver coordinates of the regularized traces are adjusted to reflect the regularizing.

Abstract: A method of filtering seismic signals is described using the steps of obtaining the seismic signals generated by activating a seismic source and recording signals emanating from the source at one or more receivers; defining a source signature deconvolution filter to filter the seismic signal, wherein the filter is scaled by a frequency-dependent term based on an estimate of the signal-to-noise (S/N) based on the spectral power of a signal common to a suite of angle-dependent far-field signatures normalized by the total spectral power of the signatures within the angular suite and performing a source signature deconvolution using the source signature deconvolution filter.

Abstract: Systems and methods for acquiring seismic data are described, one system comprising one or more seismic sources, a plurality of sensor modules each comprising a seismic sensor configured to sample analog seismic data, each module comprising a comparing unit comprising software; wherein the software in each module tests clock quality by running a sigma-delta modulator from two different clock sources in the node and compares a noise-floor of the modulator when using the different clocks.

Abstract: Marine towed streamer seismic data are combined from a first survey and a second survey, wherein the first survey and the second survey are shot with a bin size of L×L and the second survey is shot with a shooting direction rotated 90° relative to the shooting direction of the first survey. The combined seismic data from the first and second surveys are binned on a bin grid with a bin size of L 2 × L 2 and with a bin grid orientation rotated 45° relative to the shooting directions of the first and second surveys. Then, seismic data processing is applied to the binned seismic data to create an image of the Earth's subsurface.

Abstract: Diagonal gather trace interpolation systems and methods are disclosed. In some embodiments, the method includes obtaining seismic traces from a marine seismic survey performed using typically two seismic sources fired in a flip-flop pattern. The seismic traces are processed in common field file trace groups from each cable by performing trace interpolation in opposing diagonal directions. Among other things, diagonal trace interpolation may improve azimuthal regularization. In any event, the disclosed interpolation methods maintain spatial bandwidth increased spatial resolution with increased inline and crossline sampling components. Diagonal gather trace interpolation exploits reduced input trace separation to provide improved stability and detection of a greater range of formation dip angles. After interpolation and regularization, the seismic traces may be imaged and interpreted for improved seismic exploration and monitoring.

Abstract: A marine seismic streamer includes at least one particle motion sensor array. The array includes a plurality of particle motion sensors disposed at spaced apart locations along the streamer. Outputs of the particle motion sensors are functionally coupled to form an array. A number of the particle motion sensors and a spacing between adjacent particle motion sensors are selected to attenuate noise in a selected mode of propagation and within a selected wavenumber range. The streamer includes means for weighting a signal output of each particle motion sensor in the at least one array. A signal weight applied to each sensor by the means for weighting is selected to optimize attenuation of the noise.

Abstract: A device and method for determining bottom sediment is provided. The method includes transmitting a pulse of a pulse width corresponding to a water-bottom depth, extracting a series of amplitude data of water-bottom echo signals from predetermined signals among the water-bottom echo signals received by the transducer at a predetermined time interval, normalizing the extracted series of amplitude data after TVG-processed, calculating two or more feature quantities based on the normalized series of amplitude data in each of segments of the normalized series of amplitude data, and a value corresponding to the water-bottom depth, and generating bottom-sediment classification information indicating the bottom sediment based on the two or more feature quantities.

Abstract: A technique includes towing a particle motion sensor in connection with a seismic survey and controlling the survey to cause a notch in a frequency response of the particle motion sensor to substantially coincide with a frequency band at which aliased vibration noise appears in a seismic signal acquisition space of the particle motion sensor.

Abstract: A method for correcting marine seismic data is described in which a measured surface elevation relative to a reference surface of an array of source units is used to compensate for variations in the height and/or shape of a sea surface. Various embodiments correct for the elevation of the array as a whole, differences in the elevation of source units within the array, and scattering from the sea surface which arises due to the sea surface not being flat.

Abstract: Particle motion sensor signals and the pressure sensor signals data from a towed marine seismic streamer are combined to generate an up-going pressure wavefield component and a down-going particle motion wavefield component. The down-going particle motion wavefield component is extrapolated from the receiver position depth level to the source position depth level. The up-going pressure wavefield component is multiplied by the extrapolated down-going particle motion wavefield component, generating a first product. Then, nth order surface related multiples in the pressure wavefield are iteratively calculated utilizing a product of (n?1)th surface related multiple free data and the extrapolated down-going particle motion wavefield component. The calculated nth order surface related multiples are iteratively subtracted from the recorded pressure wavefield, generating the nth order surface related multiple free data.

Abstract: There is provided herein a system and method of acquiring, processing, and imaging transient Controlled Source ElectroMagnetic (t-CSEM) data in ways that are similar to those used for seismic data. In particular, the instant invention exploits the time-distance characteristics of t-CSEM data to permit the design and execution of t-CSEM surveys for optimal subsequent processing and imaging. The instant invention illustrates how to correct t-CSEM data traces for attenuation and dispersion, so that their characteristics are more like those of seismic data and can be processed using algorithms familiar to the seismic processor. The resulting t-CSEM images, particularly if combined with corresponding seismic images, may be used to infer the location of hydrocarbon reservoirs.

Abstract: A method for identifying a position of a source of noise in a marine seismic record includes defining, for at least one shot record, a set of possible noise source positions. A difference between travel time of noise from each possible noise source position to each of a plurality receiver position for the at least one shot record is determined. Signals from at least a subset of the receiver positions are time-aligned with respect to the difference between travel times for each possible noise source position. The time-aligned signals are then stacked. The noise source position is determined from the stacked, time-aligned signals. This result can then be used to construct a model of the noise at the receiver position.

Abstract: The present invention provides a method and apparatus for wave field separation. The method includes accessing a marine seismic data set acquired by a plurality of receivers deployed at a first plurality of depths in response to a plurality of acoustic signals provided by a plurality of seismic sources deployed at a second plurality of depths and forming at least one de-ghosted marine seismic data set based upon the plurality of seismic data sets.

Abstract: A technique includes obtaining seismic data, which was acquired during a seismic survey in seawater. The technique includes based on the seismic data, determining a conductivity of the seawater and processing data obtained from an electromagnetics-based survey based on the determined conductivity.

Abstract: A technique includes estimating propagation parameters that are associated with a towed seismic survey based at least in part on seismic signal measurements and noise measurements.

Abstract: The invention relates to a process for marine seismic exploration at least two different depths by means of streamers, each including a set of hydrophones, the acquisition of data at the different depths being performed in a single exploration region, and in which the position of the streamers and the hydrophones when acquiring seismic data at a first depth is independent of the position of the streamers and hydrophones when acquiring seismic data at a second depth.

Abstract: A lateral force and depth control device for a marine streamer includes a housing configured to be coupled within the streamer. A control surface is mounted to the housing such that a rotary orientation and an angle of attack of the control surface with respect to the housing are changeable. The device includes means for moving the control surface to a selected rotary orientation with respect to the housing. The device includes means for moving the control surface to a selected angle of attack with respect to the housing. A removable coupling is provided to couple the control surface to the means for moving to a selected rotary orientation and means for moving to a selected angle of attack.

Abstract: An appropriate rock physics model is chosen from well-log data and/or experience. The rock physics model is then used to generate a plurality of attribute values, including compression and shear velocities, at different porosities and gas hydrate saturations. Gas hydrates are classified into different ranges of porosity and hydrate saturation based on the population of multiple attributes, and probability density functions for each individual gas hydrate class are created. Probability density distribution functions for individual attributes and a joint conditional probability density functions are created using a Bayesian function. The conditional probability of the occurrences of gas hydrate classes given a set of values of the chosen attributes derived from seismic inversion and or well measurements is inverted. Finally, a maximum a-posteriori (MAP) rule is employed to obtain the optimal porosity and hydrate saturation estimation.

Abstract: A technique includes obtaining particle motion data and pressure data that are acquired by seismic sensors while in tow. The sensors are part of a plurality of streamers, and the pressure and particle motion data contain surface ghosts. The technique includes processing the particle motion data and the pressure data to generate a data set that is indicative of a pressure wavefield at positions between the streamers and is substantially free of the surface ghosts.

Abstract: Particle motion sensor signals and the pressure sensor signals data from a towed marine seismic streamer are combined to generate an up-going pressure wavefield component and a down-going particle motion wavefield component. The down-going particle motion wavefield component is extrapolated from the receiver position depth level to the source position depth level. The up-going pressure wavefield component is multiplied by the extrapolated down-going particle motion wavefield component, generating a first product. Then, nth order surface related multiples in the pressure wavefield are iteratively calculated utilizing a product of (n?1)th surface related multiple free data and the extrapolated down-going particle motion wavefield component. The calculated nth order surface related multiples are iteratively subtracted from the recorded pressure wavefield, generating the nth order surface related multiple free data.

Abstract: A system for marine seismic surveying comprises at least one marine seismic streamer; at least one pressure sensor mounted in the at least one marine seismic streamer; at least one particle motion sensor mounted in the at least one marine seismic streamer and collocated with the at least one pressure sensor, wherein the at least one particle motion sensor has a resonance frequency above 20 Hz; and computer means for combining pressure data from the at least one pressure sensor and particle motion data from the at least one particle motion sensor for further processing.

Abstract: In an under water detection for detecting the phase difference of an echo by two reception beams according to a split beam method, the difference ?? between the phase difference of an echo detected by first and second reception beams formed in some direction and the phase difference of the echo detected by first and second reception beams which is formed in a direction rotated from the former direction concerned by a predetermined angle is detected by a phase detector. A reliability judging unit judges whether the difference ?? detected by the phase detector is within a predetermined range or not. If the difference ?? is within the predetermined range, an echo is displayed on a display unit. If the difference ?? is not within the predetermined range, the echo is displayed with a specific color tone or the echo is not displayed.

Abstract: The present invention provides a method and apparatus for seismic data acquisition. One embodiment of the method includes accessing data acquired by at least two particle motion sensors. The data includes a seismic signal and a noise signal and the at least two particle motion sensors being separated by a length determined based on a noise coherence length. The method may also include processing the accessed data to remove a portion of the noise signal.

Abstract: Systems and methods for asynchronously acquiring seismic data are described, one system comprising one or more seismic sources, a plurality of sensor modules each comprising a seismic sensor, an A/D converter for generating digitized seismic data, a digital signal processor (DSP), and a sensor module clock; a seismic data recording station; and a seismic data transmission sub-system comprising a high precision clock, the sub-system allowing transmission of at least some of the digitized seismic data to the recording station, wherein each sensor module is configured to periodically receive from the sub-system an amount of the drift of its clock relative to the high precision clock. This abstract is provided to comply with rules requiring an abstract to ascertain the subject matter of the disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A method of determining a vertical component of particle velocity from seismic data acquired using at least one receiver disposed within a water column comprises determining the vertical component of particle velocity from the pressure at a first location and a second location. The first location is the location of a first receiver, and is vertically beneath the second location. The method uses an operator accurate for seismic data acquired at a vertical separation between the first and second locations of up to at least 0.4 times the minimum wavelength of seismic energy used to acquire the seismic data. The second location may be at or above the surface of the water column. Alternatively, the method may be applied to a twin streamer seismic surveying arrangement in which the second location is below the surface of the water column and is the location of a second receiver.

Abstract: A method for utilizing a matched field-processing algorithm employing a number of sensors wherein the sensor output is the measured acoustic data as the first input and is translated to a frequency by applying a Fourier transform to a set of time samples as a data vector output. A replica vector is the second data input as a predicted quantity which is computed by an acoustic model with an assumed acoustic location. The output is an ambiguity surface ranging between zero and one with the highest values indicating the likely position of an acoustic location. The matched field response is generalized by averaging the response over multiple frequencies. A response for an array may be computed by forming beams and then combining them by multiplying each by an eigenray factor before summing. The computation of the response may be further defined by voxel interpolation.

Abstract: Methods for generating a time lapse difference image. In one implementation, the method includes estimating a trace in a first seismic survey data set at each trace coordinate of a second seismic survey data set, estimating a trace in the second seismic survey data set at each trace coordinate of the first seismic survey data set and calculating trace differences between the first seismic survey data set and the second seismic survey data set at each trace coordinate of the first seismic survey data set and the second seismic survey data set.

Abstract: A method includes: acquiring a set of multicomponent seismic data in a towed-array, marine seismic survey at a low seismic frequency and at a deep tow depth; and processing the acquired seismic data to attenuate the affect of reverberations in the water column thereon. A method for processing seismic data includes: accessing a set of multicomponent seismic data acquired in a towed-array, marine seismic survey at a low seismic frequency and at a deep seismic depth; and processing the acquired seismic data to attenuate the affect of reverberations in the water column thereon. A method of acquiring multicomponent seismic data includes: towing a marine seismic array at a deep seismic depth; imparting a seismic survey signal into the marine environment, the seismic survey signal having a low seismic frequency; detecting a reflection of the seismic survey signal with the towed marine seismic array; and recording the detected reflection.

Abstract: The invention relates to processing seismic data that contains both a desired signal and swell noise. The method is applicable to seismic data is in the frequency-space domain method and comprises determining a signal-only prediction filter from the seismic data at a first frequency at which swell noise is not present, and applying the prediction filter to seismic data at a second frequency at which swell noise is present. This attenuates swell noise in the seismic data at the second frequency. In one embodiment, the prediction filter for a frequency fL, the lowest frequency at which swell noise is present, is determined from seismic data at frequency fH+1, where fH is the highest frequency at which swell noise is present. The prediction filter for a frequency fL+1 is determined from seismic data at frequency fH+2, and so on, so that the prediction filter for frequency fH+1 is determined from seismic data at frequency f2H?L+1.

Abstract: The present invention provides a method and apparatus for wave field separation. The method includes determining a first operator using marine seismic data acquired at a first depth and receivers deployed at a second depth, determining a second operator using marine seismic data acquired at a second depth, wherein the second depth is greater than the first depth, and forming a de-ghosted data set from the marine seismic data set based upon the first and second operators.

Abstract: Signals detected by particle motion sensors in a towed dual sensor marine seismic streamer are scaled to match signals detected by pressure sensors in the streamer. The pressure sensor signals and the scaled particle motion sensor signals are combined to generate up-going and down-going pressure wavefield components. The up-going and down-going pressure wavefield components are extrapolated to a position just below a water surface. A first matching filter is applied to the extrapolated down-going pressure wavefield component. The filtered down-going pressure wavefield component is subtracted from the extrapolated up-going pressure wavefield component, generating an up-going pressure wavefield component with attenuated particle motion sensor noise. A second matching filter is applied to the extrapolated up-going pressure wavefield component.

Abstract: Signals of pressure sensors and particle motion sensors located in marine seismic streamers are combined to generate pressure sensor data and particle motion data with substantially the same broad bandwidth. The noisy low frequency part of the motion signals are calculated from the recorded pressure signals and merged with the non-noisy motion signals. The two broad bandwidth data sets can then be combined to calculate the full up- and down-going wavefields.

Abstract: A method includes conditioning a set of multicomponent seismic data and sensor orientation data, the multicomponent seismic data including pressure data and particle motion data, acquired in a towed array, marine seismic survey; digital group forming the conditioned pressure data, a vertical particle motion component of the conditioned particle motion data, and the conditioned sensor orientation data; and summing the digitally group formed pressure data and the digitally group formed vertical particle motion component.

Abstract: An up-going wavefield and a down-going wavefield are calculated at a sensor position from a pressure sensor signal and a particle motion sensor signal. Then, an up-going wavefield is calculated at a water bottom position substantially without water bottom multiples from the up-going and down-going wavefields at the sensor position. In one embodiment, the up-going wavefield at the sensor position is backward propagated to the water bottom, resulting in an up-going wavefield at the water bottom. The down-going wavefield at the sensor position is forward propagated to the water bottom, resulting in a down-going wavefield at the water bottom. The up-going wavefield at the water bottom without water bottom multiples is calculated from the backward propagated up-going wavefield at the water bottom, the forward propagated down-going wavefield at the water bottom, and a reflection coefficient of the water bottom.

Abstract: A method for reconstructing seismic data signals of poor quality to improve the signal-to-noise ratio of the data for display and analysis in connection with the selection of drilling sites for recovery of hydrocarbons. The method includes providing a signal model by applying a Karhunen-Loeve transform to selected input seismic data collected for the target zone, to form a co-variance matrix from the dot products of all pairs of input data. Eigenvalues and eigenvectors for the matrix are computed, and the most significant eigenvectors are inversely transformed to provide a coherent estimate of the signal. The input data is combined with the model data based on the determination that the model data lacks continuity, wherein the good quality signal-to-noise ratio data experiences little change and discontinuous data is enhanced by a contribution of the signal estimate data. The reconstructed seismic data of the target zone can be displayed for analysis.

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 for computing a pressure signal gradient. The method includes recording a plurality of pressure signals at least one of a first receiver and a second receiver. The first receiver and the second receiver are disposed within a cluster. The method further includes recording a plurality of pressure signals at the second receiver; computing a calibration filter for removing the difference in distortions between the pressure signals recorded at the first receiver and the pressure signals recorded at the second receiver; and computing the pressure signal gradient between the pressure signals recorded at the first receiver and the pressure signals recorded at the second receiver using the calibration filter.

Abstract: A technique for use in towed-array, marine seismic surveys includes a method and an apparatus. The method includes accessing a set of multicomponent seismic data acquired in a wide tow, marine seismic survey; and interpolating a set of seismic data from the acquired seismic data in the crossline direction such that the combined acquired and interpolated seismic data meet the discrete spatial sampling theory requirements for array detection of broadside seismic signal and the discrimination and suppression of broadside linear noise. In some aspects, the technique includes programmed storage media and/or programmed computers for use in executing such a method. The apparatus is a wide tow array, including a plurality of streamers spaced apart by a cable separation exceeding the maximum cable spacing for array detection of broadside seismic signal and the discrimination and suppression of broadside linear noise as determined by discrete spatial sampling theory.

Abstract: The present invention provides a method and apparatus for marine seismic data acquisition. The method may include determining a seismic source signature based on a pressure wave field and at least one component of particle motion measured by at least one seismic sensor while in tow.

Abstract: A method and apparatus is provided for determining a propagation time delay. The apparatus includes at least one source adapted to generate a plurality of positioning signals, at least one receiver deployed along a seismic sensing cable, wherein the receiver is adapted to receive the plurality of positioning signals from the at least one source, and a plurality of computed Doppler-shifted positioning signals corresponding to the plurality of positioning signals. The apparatus also includes a signal processing unit adapted to determine a propagation time delay between the source and the receiver using the generated positioning signals, the received positioning signals, and the plurality of computed Doppler shifted positioning signals.

Abstract: A downhole tool for gathering formation data from inside a borehole includes a substantially tubular housing adapted for axial connection to a drill string and multiple sensors coupled to the tubular housing. The sensors include a first pair of sensors aligned along a first axis and adapted to measure a spatial derivative along the first axis, a second pair of sensors aligned along a second axis and adapted to measure a spatial derivative along the second axis, and a third pair of sensors aligned along a third axis and adapted to measure a spatial derivative along the third axis. In selected embodiments, the spatial derivatives are used to differentiate seismic or sonic compression and shear waves measured in a downhole environment.

Abstract: A system for remotely controlling, acquiring and monitoring the acquisition of seismic data. The system includes remote equipment for collecting seismic data and for transmitting and receiving communication signals to and from a remote location. The system also includes local equipment for transmitting and receiving communication signals to and from the remote location. In this manner, the collection of seismic data at remote locations can be controlled and monitored locally.

Abstract: A method of determining seismic properties of a layer of the seabed, in particular a surface or near-surface layer (5), comprises directing seismic energy propagating in a first mode at a boundary face of the layer so as to cause partial mode conversion of the seismic energy at the boundary face. For example partial mode conversion may occur when seismic energy propagates upwards through the interface between a surface or near-surface layer (5) and the basement (6), owing to the difference in seismic properties between the surface or near-surface layer (5) and the basement (6). In the invention, the two modes of seismic energy—that is the initial mode and the mode generated by mode conversions at the interface—are received at a receiver. The difference in travel time of the two modes between the interface and the receiver is determined from the seismic data acquired by the receiver.

Abstract: A system and method are provided for detecting an acoustic signal in the presence of flow noise produced by the turbulent flow field that develops about a hosewall of a towed array. Pressure is sensed with pressure sensors at two diametrically-opposed locations at the surface of the hosewall over a period of time. The sensed pressure signals are used to generate an ensemble-averaged cross-spectra which effectively cancels out the flow noise while retaining the acoustic signal associated with a possible target of interest.

Abstract: A method is disclosed for deghosting seismic data. The data include measurements of a vertical component of particle motion and pressure. The measurements are substantially collocated and made at a plurality of spaced apart positions. The method includes transforming the data into the spatial frequency domain, and separating upgoing and downgoing wavefield components of the transformed data. Water surface multiples may also be removed by decomposing the signals made at a plurality of seismic energy source locations into upgoing and downgoing wavefields.

Abstract: An electronic-carrying module (640), for example for use with a seismic data acquisition cable (400), is disclosed. The preferred electronic-carrying module (640) includes, first, an electronics carrier (106) having access means (107) for providing an easy-to-reach access to wrap-around circuitry fitted inside a curved space (104a) within the electronics carrier (106). Second, a pair of rigid end-fittings (102) spaced apart axially by the electronics carrier (106) for connecting to a section of the seismic data acquisition cable (400). And third, an axial hole (100) formed in the electronics carrier (106) and the rigid end-fittings (102) defining the curved space (104a) between the axial hole (100), the access means (107) and the rigid end-fittings (102).

Abstract: A seismic sensor cable is disclosed. The cable includes an outer jacket disposed on an exterior of the cable. The outer jacket excludes fluid from entering an interior of the cable. A reinforcing layer disposed within the outer jacket, which includes at least one electrical conductor disposed therein. An inner jacket is disposed within the reinforcing layer, and at least one electrical conductor disposed within an interior of the inner jacket. Some embodiments include at least one seismic sensor electrically coupled to the at least one electrical conductor disposed in the reinforcing layer In some embodiments a housing is disposed over the electrical coupling of the sensor to the conductor. The housing is molded from a polyurethane composition adapted to form a substantially interface-free bond with the cable jacket when the polyurethane cures.