Abstract: A technique includes obtaining seismic data acquired by at least one seismic sensor. The technique includes processing the seismic data to determine a value that is indicative of a three-dimensional directional propagation attribute of a seismic event based on the seismic data.

Abstract: A method determining a calibration filter to calibrate a first component of multi-component seismic data relative to a second component of the seismic data comprises determining the calibration filter from a portion of the seismic data that contains only events arising from critical refraction of seismic energy. The method is particularly suitable for long-off-set data, since the first arrival will be a critical refraction event and an automatic picking method may be used. The present invention also provides a wavenumber dependent calibration filter that is obtained from a calibration filter obtained from data in one offset range and another calibration filter obtained from data in another offset range.

Abstract: The technologies described herein include systems and methods for encoding/decoding seismic sources and responses, generating and using of source-side derivatives while also generating and using the conventional source response. Sources in an array may be encoded such that activation of each source in the array constitutes a single spike in a sequence orthogonal to another sequence emitted by another source. The responses to these different sources that are in close spatial proximity can be decoded and separated. Source-side derivatives may be calculated and utilized in various applications in combination with the monopole response from the source location, including source-side deghosting, spatial (horizontal and vertical) interpolation and imaging.

Abstract: A technique includes obtaining pressure data that was acquired by seismic sensors towed as part of a three-dimensional spread of streamers and obtaining particle motion data, which are indicative of particle motion at locations of the sensors. The technique includes estimating cross-line spectra of the pressure data based at least in part on the pressure data, and the technique includes deghosting the particle motion data based at least in part on the estimated cross-line spectra.

Abstract: The technologies described herein include systems and methods for encoding/decoding seismic sources and responses, generating and using of source-side derivatives while also generating and using the conventional source response. Sources in an array may be encoded such that activation of each source in the array constitutes a single spike in a sequence orthogonal to another sequence emitted by another source. The responses to these different sources that are in close spatial proximity can be decoded and separated. Source-side derivatives may be calculated and utilized in various applications in combination with the monopole response from the source location, including source-side deghosting, spatial (horizontal and vertical) interpolation and imaging.

Abstract: The present invention relates to a method of processing data representing energy propagating through a medium (e.g., acoustic, elastic or electromagnetic energy) and describes an efficient and flexible e approach to forward modeling and inversion of such energy for a given medium. The representation theorem for the wave-equation is used, in combination with time-reversal invariance and reciprocity, to express the Green's function between two points in the interior of the model as an integral over the response in those points due to sources regularly distributed on a surface surrounding the medium and the points.

Abstract: Implementations of various technologies for processing seismic data. In one implementation, the seismic data may be processed by creating a fictitious source-receiver line connecting a source with a receiver location of interest, projecting one or more receiver locations adjacent the receiver location of interest onto the fictitious source-receiver line and decomposing seismic data on the receiver locations disposed on the fictitious source-receiver line into up-going wavefields and down-going wavefields.

Abstract: A method of acquiring or processing multi-component seismic data obtained from seismic signals propagating in a medium, the method comprising the steps of: selecting a first portion of the seismic data in which the first arrival contains only upwardly propagating seismic energy above the seafloor; and determining a first calibration filter from the first portion of the seismic data, the first calibration filter being to calibrate a first component of the seismic data relative to a second component of the seismic data.

Abstract: A method of processing seismic data that includes including first and second modes of seismic energy where the second mode has been generated by partial mode conversion of the first mode at a boundary face of a layer of the seabed includes the step of cross-correlating a trace acquired at a receiver and including events corresponding to the first mode with a trace acquired at the same receiver and including events corresponding to the second mode. An event in the cross-correlated data that corresponds to partial mode conversion is identified, and the amplitude of this event is normalized, for example relative to the amplitude of the peak in the cross-correlogram at zero time delay. Information about the effects of the static shift produced by the layer and/or about vector infidelity can be arrived from normalized cross-correlograms for receivers in a receiver array.

Abstract: A method and apparatus implementing a technique for mitigating noise in seismic data are presented. The technique includes estimating a noise component in a set of multicomponent seismic data representing a recorded wavefield from the relationship at the free surface of an upgoing component and a downgoing component decomposed from the recorded wavefield; and removing the estimated noise component from the seismic data. The noise component can be estimated by decomposing a recorded wavefield into an upgoing component and a downgoing component and isolating a noise component in the recorded wavefield from the relationship of the decomposed upgoing and downgoing components at the free surface.

Abstract: There is described a method of moveout or velocity analysis of seismic signals using the steps of obtaining such signals 5 from a plurality of receivers, identifying receiver functions within the acoustic signals, analyzing said receiver functions for velocity or moveout characteristics, using the result of said analyzing step to determine, properties of multiple layers of earth located below said 10 receivers. The analyses can involve the use of representation of the traveltime differences as approximated power series of slowness or horizontal distances. The method is the first to comprehensively deal with a multi-layered earth or velocity model.

Abstract: A method of processing seismic data that includes including first and second modes of seismic energy where the second mode has been generated by partial mode conversion of the first mode at a boundary face of a layer of the seabed includes the step of cross-correlating a trace acquired at a receiver and including events corresponding to the first mode with a trace acquired at the same receiver and including events corresponding to the second mode. An event in the cross-correlated data that corresponds to partial mode conversion is identified, and the amplitude of this event is normalized, for example relative to the amplitude of the peak in the cross-correlogram at zero time delay. Information about the effects of the static shift produced by the layer and/or about vector infidelity can be arrived from normalized cross-correlograms for receivers in a receiver array.

Abstract: A method of processing multi-component seismic data acquired at a receiver station comprises determining a calibration filter that calibrate a first component of the seismic data relative to a second component of the seismic data in order to compensate for differences in coupling between the two components. The determination of the calibration filter comprises processing the data in the common shot domain. This allows optimisation criteria to be applied to the up- and down-going constituents of particle velocity, and this is simpler than prior art methods of applying optimisation criteria to the up-going and down-going constituents of the pressure.

Abstract: The technologies described herein include systems and methods for encoding/decoding seismic sources and responses, generating and using of source-side derivatives while also generating and using the conventional source response. Sources in an array may be encoded such that activation of each source in the array constitutes a single spike in a sequence orthogonal to another sequence emitted by another source. The responses to these different sources that are in close spatial proximity can be decoded and separated. Source-side derivatives may be calculated and utilized in various applications in combination with the monopole response from the source location, including source-side deghosting, spatial (horizontal and vertical) interpolation and imaging.

Abstract: Implementations of various technologies for processing seismic data. In one implementation, the seismic data may be processed by creating a fictitious source-receiver line connecting a source with a receiver location of interest, projecting one or more receiver locations adjacent the receiver location of interest onto the fictitious source-receiver line and decomposing seismic data on the receiver locations disposed on the fictitious source-receiver line into up-going wavefields and down-going wavefields.

Abstract: Described is a finite-difference methodology for efficiently computing the response from a model subject to changes within sub-volumes with the sub-volume enclosed with an extrapolation surface within an injection boundary using Green's functions to update the injection boundary and transmitting an updated wavefield from the injection boundary back into the altered sub-volume to include higher order reflections from outside of the altered sub-space.

Abstract: A data set can be corrected for the effects of interface waves by interferometrically measuring an interface wavefield between each of a plurality of planned locations within a survey area; and correcting survey data acquired in the survey area for the interface waves. The interface wavefield may be interferometrically measured by receiving a wavefield including interface waves propagating within a survey area, the survey area including a plurality of planned survey locations therein; generating interface wave data representative of the received interface wavefield; and constructing a Green's function between each of the planned survey positions from the interface wave data. Other aspects include an apparatus by which the interface wavefield may be interferometrically measured and a computer apparatus programmed to correct the seismic data using the interferometrically measured interface wave data.

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 method determining a calibration filter to calibrate a first component of multi-component seismic data relative to a second component of the seismic data comprises determining the calibration filter from a portion of the seismic data that contains only events arising from critical refraction of seismic energy. The method is particularly suitable for long-off-set data, since the first arrival will be a critical refraction event and an automatic picking method may be used. The present invention also provides a wavenumber dependent calibration filter that is obtained from a calibration filter obtained from data in one offset range and another calibration filter obtained from data in another offset range.

Abstract: A method of processing multi-component seismic data acquired at a receiver station comprises determining a calibration filter that calibrate a first component of the seismic data relative to a second component of the seismic data in order to compensate for differences in coupling between the two components. The determination of the calibration filter comprises processing the data in the common shot domain. This allows optimisation criteria to be applied to the up- and down-going constituents of particle velocity, and this is simpler than prior art methods of applying optimisation criteria to the up-going and down-going constituents of the pressure.