towed streamer
`Acquisition of marine point receiver seismic data with
`Au Ozbek Leendert Combee Nils Lunde Simon Bittleston and Ed Kragh
`James Martin
`
`Schlumberger
`
`Summary
`
`new concept
`towed
`for the acquisition of point receiver
`streamer data is introduced Recording of point receiver
`than the analogue outputs of hardwired arrays
`data rather
`both
`enhanced
`forming and
`dynamic
`enables
`group
`attenuation of noise Dynamic group fonning allows better
`and enhanced
`recovery
`signal preservation
`frequency
`far offsets Data adaptive noise attenuation
`particularly at
`methods allows improved attenuation of the low frequency
`flow around the streamer enabling
`noise induced by water
`the enhancement of the low frequency
`ratio
`signal-to-noise
`filters Point receiver marine
`through avoidance of low cut
`improve the dynamic range of the seismic
`seismic data will
`the viability of time-lapse monitoring of
`signal and enhance
`reservoirs with towed streamer data
`
`Introduction
`
`array
`
`response
`
`is
`
`attenuation
`
`bottom describes the system for
`Figure
`recording point receiver marine seismic data
`
`Analogue Group Forming
`
`Digital Group Forming
`
`towed streamer marine
`The current method of acquiring
`the deployment of 2D arrays of
`seismic data involves
`hydrophones which are distributed along the length of each
`The individual
`outputs of each
`hydrophone
`streamer
`within an array are hardwired together
`to give an analogue
`The analogue
`then
`response
`array
`digitised and
`transmitted
`
`to
`
`the
`
`along
`
`the
`
`streamer
`The
`instrument on the vessel
`individual
`forming the 2D arrays are often distributed
`and these analogue arrays
`spacing
`with non-equidistant
`to enhance
`may overlap with one another
`their frequency
`The 2D arrays
`independent wavenumber
`response
`filtering of the
`spatial anti-alias
`are designed to provide
`seismic data and attenuate both in-line water-borne noise
`and water cross-flow induced noise The 2D hydrophone
`forms an
`wavenumber
`analogue
`that
`top provides
`invariant Figure
`schematic
`frequency
`illustration of hard-wired group-formed data recording
`
`recording
`
`hydrophones
`
`filter
`
`array
`
`filter
`
`is
`
`novel
`
`system
`The
`
`towed streamer seismic data acquisition
`recording has been developed
`utilising point receiver
`and
`recent advances
`in both electronics
`system exploits
`data communication
`to allow the recording of
`networks
`more than 4000 individual hydrophones
`on each of up to
`20 streamers giving
`total of up to 80000 channels
`The
`system incorporates
`sophisticated
`signal
`processing
`software for real-time digital group forming of the point
`receiver data
`The signal processing
`sofrware allows for
`in the seismic data and
`the correction of perturbations
`
`completes
`which
`
`real-time intelligent
`
`group forming
`noise
`high-fidelity data-adaptive
`
`dynamic
`
`incorporates
`
`SEC 2000 Expanded Abstracts
`
`Figure
`
`comparison
`
`of
`
`the systems
`used
`acquire
`top and point
`conventional
`hard-wired
`formed data
`group
`receiver digital data with real-time data adaptive noise attenuation
`
`to
`
`Signal and Noise
`
`One of the key sources of marine seismic data quality
`degradation is the reliance on hardwired
`group forming in
`Newman
`1973
`and Mahoney
`conventional
`systems
`how the performance of hardwired
`described
`analogue
`arrays would be compromised
`by errors in the positioning
`
`PGS Exhibit 1072, pg. 1
`PGS v. WesternGeco (IPR2014-00688)
`
`

`

`Acquisition of marine point receiver seismic data with
`
`towed streamer
`
`is
`
`vertical
`
`incidence
`
`at
`
`wavenumber
`The signal
`
`pass
`
`Another undesirable property of hardwired anatogue arrays
`because
`of non-
`the attenuation of the desired signal
`shows the
`the streamer Figure
`typical marine hardwired array
`response of
`and 0.07m
`region lies between 0mt
`wavenumbers
`with the
`noise
`attenuation
`region
`wavenumbers greater than 0.07mt The gain of the filter
`in
`for the Omt
`to
`the signal
`region is only equal
`pass
`wavenumber which corresponds to vertical
`The gain of the wavenumber
`filter drops off with
`array
`which means that
`increasing wavenumber
`the
`higher
`the receiver array will be
`frequencies of signals arriving at
`attenuated by hardwired array forming
`
`for
`
`incidence at the
`
`5.-
`
`10
`
`-15
`
`20
`25
`
`-40-
`
`45
`
`0.05
`
`0.1
`
`015
`Waoonurnber
`
`02
`
`025
`
`0.3
`
`Figure
`
`Typical wavenumber
`receiver array
`
`response of
`
`hardwired marine
`
`Deviation
`
`from vertical
`
`incidence
`
`at
`
`the receiver
`
`array
`becomes more pronounced as the distance from the source
`incidence also
`to the receiver array increases Non-vertical
`dominates
`recording of diffractions
`the
`from complex
`The
`sub-surface
`structures
`frequency
`independent nature of hardwired analogue arrays attenuates
`frequencies from events amving at
`the receiver
`the higher
`angles of incidence
`array at non-vertical
`
`and
`
`reflections
`
`The
`
`length of
`
`the
`
`receiver
`
`array
`
`is
`
`key parameter
`
`determining
`
`the
`
`amount
`
`of
`
`high
`
`frequency
`
`signal
`
`the streamer at
`
`attenuation suffered by events that arrive at
`incidence
`angles of
`shows the
`non-vertical
`Figure
`impact of array length on the pre-stack signal bandwidth of
`from depth of 3km recorded at an
`target reflector
`typical
`offset of 2000m from the seismic source An 80Hz signal
`60Hz
`12m linear array
`is attenuated by about 6dB by
`6m linear arrays attenuate
`signal suffers 3dB attenuation
`80Hz signal by only about 1dB
`
`Hardwired
`
`arrays therefore compromise
`and vertical
`resolution of complex and dipping structures
`during imaging Hardwired
`arrays also impose an offset-
`
`the bandwidth
`
`and
`
`elements
`01
`the
`individual
`sensor
`sensitivity
`and Huizer 1987 showed that uncorrected
`individual sensors would
`the
`introduce
`
`Ongkiehong
`
`perturbations
`
`at
`
`pseudo-random noise-beneath-the-signal
`The noise-beneath-the-signal
`data upon array forming
`often defines the random noise level measured in seismic
`data and limits the effective dynamic range of the seismic
`signal
`
`into the seismic
`
`top shows
`synthetic marine seismogram after
`sensor elements that had
`group forming of individual
`The FK
`standard deviation
`1000 sensitivity
`typical
`spectrum shows defocusing of the seismic energy as it
`smeared across all wavenumbers
`The pseudo-random
`smeared signal often defines the noise
`noise that
`is the
`limiting the dynamic range of our desired seismic
`
`Figure
`
`floor
`
`is
`
`signal
`
`1000 Hydrophone Sensitivity Perturbation
`
`43.05
`0.05
`Wavenumber 1/rn
`
`Synthetic manne seismic record top which was group
`Figure
`bOo
`elements
`standard
`formed from hydrophone
`having
`The EK spectrum of
`deviation
`the seismogram
`in sensitivity
`bottom shows the smearing of signal across all wavenumbers
`generating pseudo-random noise behind the signal
`
`SEG 2000 Expanded Abstracts
`
`PGS Exhibit 1072, pg. 2
`PGS v. WesternGeco (IPR2014-00688)
`
`

`

`Acquisition of marine point receiver seismic data with
`
`towed streamer
`
`is
`
`One of the key requirements of noise attenuation filtering
`sampling of both the noise modes and the
`prior adequate
`desired signal The swell noise waveforms
`in figure
`are
`clearly aliased even at 6.25m receiver array sampling The
`6.25m hardwired group has not been particularly effective
`ttoisc in this example Resorting to
`swell
`in attenuating
`longer array lengths would attenuate
`little more swell
`noise but would also degrade the quality and bandwidth of
`the signal as discussed earlier through the introduction of
`and
`more
`attenuation
`of high
`can be reduced in
`frequencies
`the field by towing the streamers deeper in the water and
`low cut
`The higher
`frequency
`filter
`filter obviously removes important low
`Towing
`the streamer at deeper water
`frequency
`signal
`depths lowers the frequency of the receiver ghost notch
`signal while
`attenuating
`important
`high
`frequency
`enhancing the amplitude of low frequency
`signal
`using
`range of different water depths in the same 3D survey leads
`in signal bandwidth compromising the
`to inconsistency
`final 3D images and interpretations
`
`noise-behind-the-signal
`
`Swell noise contamination
`
`applying
`frequency
`
`higher
`low cut
`
`dependent high-cut
`
`filter on pre stack data compromising
`the inversion of amplitude versus offset AVO responses
`
`Difference Spectra
`
`12
`
`Frequency Hz
`
`1U
`
`Figure
`
`The impact of receiver array length on the attenuation of
`target reflector recorded at an
`high frequency
`for
`typical
`signal
`offset of 2000m from the seismic source
`
`Point
`
`receiver
`
`recording
`
`leaves
`
`all
`
`frequencies
`irrespective of the seismic events angle of incidence at the
`receiver array
`
`intact
`
`is
`
`Figure
`
`Shows
`
`typical
`
`towed
`
`streamer shot
`
`record recorded
`
`with 6.25m hardwired
`The shot
`record
`arrays
`receiver
`contaminated with bursts of swell noise induced by the sea-state
`down the streamer at an apparent
`which
`velocity of
`3Oms
`
`propagate
`
`is
`
`Any residual swell noise left after data recording can only
`be attenuated fUrther using techniques reserved for random
`because
`the swell noise has not been
`noise suppression
`recorded with sufficient
`
`spatial
`
`fidelity
`
`to enable
`
`the
`
`that exploit spatio
`
`or
`
`incoherent
`
`noise
`
`application
`
`of
`
`filtering
`
`temporal
`
`coherency
`
`techniques
`Random
`such
`as stack band-pass filters
`suppression
`techniques
`using FX deconvolution
`random noise suppression
`or
`muting of swell noise contaminated
`traces followed by
`interpolation all have
`effect on
`detrimental
`significant
`signal bandwidth and fidelity
`
`The principal noise source affecting marine towed streamer
`induced by flow of water across the streamer
`data
`Vertical cross-flow can be induced by wave action and is
`often termed swell noise Horizontal cross-flow is induced
`by local sea water currents and as the vessel
`line changes All sources of cross-flow generate vibrattons
`that propagate down the seismic streamer
`number of
`characteristic modes
`amplitudes apparent velocities
`which
`
`turns during
`
`in
`
`frequencies
`
`are
`
`partly
`
`determined
`
`construction
`
`of
`
`the
`
`seismic
`
`streamer
`
`and
`
`and
`
`the
`
`the
`
`by
`how
`
`hydrophones
`vibrations
`
`are de-coupled
`
`from the
`
`various
`
`streamer
`
`Shows
`towed
`streamer
`shot
`record
`Figure
`typical
`recorded with 6.25m hardwired receiver arrays The shot
`record is contaminated with bursts of swell noise induced
`by the sea-state which propagate down the streamer at an
`apparent velocity of 3Oms
`The apparent velocity of the
`in part on the relative velocity of
`swell noise is dependent
`and
`the
`vessel
`currents
`Cross-flow
`the shallow sea
`induced noise is always 2D in nature as it propagates down
`the length of the streamer
`
`SEG 2000 Expanded Abstracts
`
`PGS Exhibit 1072, pg. 3
`PGS v. WesternGeco (IPR2014-00688)
`
`

`

`Acquisition of marine point receiver seismic data with
`
`towed streamer
`
`resolution of structural
`AVO anomalies
`
`images and the inversion of
`
`Offset- andlor
`
`time-dependent
`
`to improve
`
`the
`
`efficiency
`
`dynamic group forming
`of sub-surface
`image
`
`determination
`Improved survey trim around time through attenuation
`of swell- and weather-related
`noise while maintaining
`
`high signal fidelity
`Retention of low frequency
`
`signal
`
`data-adaptive
`
`beamforming instead
`
`through the use of
`of
`low cut
`
`improving
`the
`of
`acoustic
`filtering
`accuracy
`impedance inversion and matching of seismic data to
`well logs
`Time-lapse ready towed streamer seismic data High
`data
`delivered
`after
`data-adaptive
`fidelity
`beamforming and point
`receiver
`calibration will
`extend the dynamic range of the seismic signal and
`enable the monitoring of weaker
`time-lapse responses
`than can be detected
`the use of systems
`though
`employing hardwired group forming
`at both low and
`of signal bandwidth
`Improvement
`frequencies during marginal weather
`
`through
`
`high
`
`data-adaptive noise attenuation
`Acquisition of seismic data during line change through
`the attenuation of cross-flow induced noise
`Acquisition of genuine 3D towed streamer data using
`novel pseudo-random acquisition geometries enabled
`through the attenuation of cross-flow induced noise
`
`References
`
`1987 Dynamic
`range of
`and Huizer
`Ongkiehong
`the seismic system First Break 05 no 12 435-439
`
`Newman
`and Mahoney
`1973 Pattems With
`pinch of salt Geophys Prosp. 21 no 02 197-219
`
`Ozbek
`1998 Adaptive Seismic Noise and Interference
`Attenuation Method Patent application
`
`2000 Adaptive Beamforming with Generalized
`Ozbek
`Linear Constraints submitted to SEG annual conference
`Calgary
`
`Acknowledgments
`
`We would
`thank our
`like to
`colleagues
`throughout
`Schlumberger whose dedication
`and hard work over many
`recording to become
`years allowed marine point receiver
`We would also like to thank Schlumberger
`for
`reality
`permission to publish this work
`
`Too much contamination
`cross-flow induced
`noise
`
`of the seismic shot
`
`leads
`
`to
`
`the
`
`records by
`temporary
`abandonment
`of data
`until
`data
`quality
`acquisition
`improves increasing the cost of marine seismic surveying
`to both
`and delaying
`and service provider
`client
`the
`delivery of
`volume
`the
`data
`
`final
`
`processed
`
`for
`
`interpretation
`
`Point Receiver Concept
`
`filtering
`
`and the use of anti-alias
`are standard
`Sampling
`techniques in time domain digital recording In contrast
`sampling interval
`temporal sampling however
`the initial
`marine seismic streamer
`is limited by cost
`space along
`These
`and operational
`considerations
`efficiency
`and limited the design of analogue
`have always influenced
`hydrophone arrays in marine seismic streamers
`
`to
`
`in
`
`criteria
`
`Point
`receiver
`allows
`the extension of basic
`recording
`sampling rules to the spatial domain
`of
`Pre-processing
`the computation of group
`receiver
`data facilitates
`point
`formed data which is essentially free of aliased noise The
`spatial separation of point receivers distributed along the
`streamer must
`be
`chosen
`
`to
`
`facilitate
`
`the
`
`seismic
`
`attenuation of noise
`
`Once the signal and noise waveflelds
`are sampled by the
`corrections
`residual sensor calibration
`are
`to the marine
`
`point receivers
`
`applied
`
`to the data before
`transmission
`system on the vessel to enhance
`acquisition
`The calibration
`receiver
`corrected point
`powerful
`using
`real-time
`data-adaptive
`to attenuate both cross-flow induced noise
`beamformers
`and other vibration noise that may be introduced by the
`The
`towing
`vessels
`conflgnration
`data-adaptive
`beamformer
`is designed to protect
`for all of
`and wavenumbers
`the
`frequencies
`to the complete range of dips that could be
`corresponding
`the seismic streamer Ozbek 1998 and 2000
`by
`attenuation
`afforded
`the data-adaptive
`beamformer
`is applied over only that spatial and temporal
`and
`can
`be
`aperture where
`stationary
`and its signal
`The data-adaptive beamformer
`can be designed to cope with other
`component
`such as loss of
`point receiver within the
`contingencies
`streamer without significantly affecting signal
`
`signal
`
`fidelity
`
`data are
`
`then
`
`the desired seismic
`
`filtered
`
`signal
`
`expected at
`The
`
`noise
`
`attenuated
`
`protection
`
`the
`
`noise
`
`is
`
`fidelity
`
`Marine point receiver
`lead to
`
`recording
`
`in
`
`towed streamer will
`in the quality and
`revolutionary improvement
`of seismic data
`number of benefits will be
`
`flexibility
`
`afforded by point receiver recording
`
`Full signal bandwidth protection irrespective of offset
`or angle of incidence at
`Improving the
`
`the streamer
`
`SEG 2000 Expanded Abstracts
`
`PGS Exhibit 1072, pg. 4
`PGS v. WesternGeco (IPR2014-00688)
`
`

`

`This article has been cited br
`
`Nick MoldoveanuAttenuation of high energy marine towed-streamer noise 3576-3580
`Links
`
`w/
`
`Massimiliano Vassallo Kurt Eggenberger Au Ozbek Tony Curtis Dirk-Jan van Manen Ahmet Kemal Ozdemir Johan
`streamer wavefield
`reconstruction 1273-1277
`of streamer noise impact
`RobertssonMitigation
`in multicomponent
`w/Links
`
`HongYan Li Denes Vigh Jerry KapoorThe contribution of wide-azimuth point-receiver acquisition to the success of fill-wave
`inversion 2555-2559
`w/Links
`
`PGS Exhibit 1072, pg. 5
`PGS v. WesternGeco (IPR2014-00688)
`
`