Embed Size (px)
DESCRIPTION
WAVEFIELD PREDICTION OF WATER-LAYER-MULTIPLES. Ruiqing He University of Utah Feb. 2004. Outline. Introduction Theory Synthetic experiments Application to Unocal data Conclusion. Introduction. Primary-preserving multiple removal demands - PowerPoint PPT Presentation
Citation preview
WAVEFIELD PREDICTION OF WAVEFIELD PREDICTION OF WATER-LAYER-MULTIPLESWATER-LAYER-MULTIPLES
Ruiqing HeRuiqing He
University of UtahUniversity of Utah
Feb. 2004Feb. 2004
OutlineOutline
• IntroductionIntroduction
• TheoryTheory
• Synthetic experimentsSynthetic experiments
• Application to Unocal dataApplication to Unocal data
• ConclusionConclusion
IntroductionIntroduction
• Primary-preserving multiple removal demands Primary-preserving multiple removal demands
accurate wavefield prediction of multiples. accurate wavefield prediction of multiples. • Other works:Other works:
- Delft- Delft
- Amundsen, Ikelle, Weglein, etc.- Amundsen, Ikelle, Weglein, etc.
• Water layer multiplesWater layer multiples
OutlineOutline
• IntroductionIntroduction
• TheoryTheory
• Synthetic experimentsSynthetic experiments
• Application to Unocal dataApplication to Unocal data
• ConclusionConclusion
Berryhill and Wiggins’s MethodsBerryhill and Wiggins’s Methods
Off-shoreOff-shoreseismic dataseismic data
MultipleMultipleattenuationattenuation
Filtered SubtractionFiltered Subtraction
Water surface
Water bottom
Receiver line
Kirchhoff SummationKirchhoff SummationForward extrapolate tracesdown to water bottom
Kirchhoff SummationKirchhoff Summation
Forward extrapolate bottom traces up to receivers Emulated Muliples
The proposed methodThe proposed method
Off-shoreOff-shoreseismic dataseismic data
Wave forwardWave forwardextrapolation extrapolation
to the water bottomto the water bottom
Wave forwardWave forwardextrapolation extrapolation
to the receiversto the receivers
Other multipleOther multipleattenuationattenuation
filteringfiltering
Decomposition Decomposition of of
receiver-sidereceiver-sideghostsghosts
FDFD FDFD
FDFD
Multiples Multiples with last with last
round-trip round-trip in water layerin water layer
Primary-Primary-preservingpreserving
multiplemultipleremovalremoval
FD: Finite DifferenceFD: Finite Difference
DS: Direct (simple) SubtractionDS: Direct (simple) Subtraction
DSDS
Why Finite Difference?Why Finite Difference?
• AdvantageAdvantage
- speed- speed
- convenience- convenience
- capability: heterogeneous medium- capability: heterogeneous medium
• DisadvantageDisadvantage
- dispersion?: reality, high-order FD- dispersion?: reality, high-order FD
Types of Water-Layer-MultiplesTypes of Water-Layer-Multiples• LWLM: Multiples that have the last round-trip in the water layer.LWLM: Multiples that have the last round-trip in the water layer.• Other WLM: other water-layer-multiples except LWLM.Other WLM: other water-layer-multiples except LWLM.
Wavefield Extrapolation of RSGWavefield Extrapolation of RSG
Water surface
Receiver line
Mirror image ofthe Receiver line
UU RSGRSG
RSGRSG
i
iii
iii FttUr
txtRSG )*)((cos
1)(
iir
Decomposition of RSGDecomposition of RSG
UU
i
ii ttUftRSG ))(()(
RSGRSG
ff
++++ DATADATA
Water surface
Receiver line
Mirror image ofthe Receiver line
OutlineOutline
• IntroductionIntroduction
• TheoryTheory
• Synthetic experimentsSynthetic experiments
• Application to Unocal dataApplication to Unocal data
• ConclusionConclusion
Synthetic ModelSynthetic Model
DepthDepth (m)(m)
00
15001500
Offset (m)Offset (m)00 32503250
waterwater
SandstoneSandstone
Salt domeSalt dome
BSRBSR
Synthetic seismic dataSynthetic seismic data
TimeTime (ms)(ms)
400400
25002500
Offset (m)Offset (m)00 32503250
Decomposed RSGDecomposed RSG
TimeTime (ms)(ms)
400400
25002500
Offset (m)Offset (m)00 32503250
Predicted LWLMPredicted LWLM
TimeTime (ms)(ms)
400400
25002500
Offset (m)Offset (m)00 32503250
Waveform ComparisonWaveform Comparisonbetween Data & RSG between Data & RSG
Am
pli
tud
eA
mp
litu
de
Time (ms)Time (ms)600600 24002400
DataData
RSGRSG
Waveform ComparisonWaveform Comparisonbetween Data & LWLM between Data & LWLM
Am
pli
tud
eA
mp
litu
de
Time (ms)Time (ms)600600 24002400
DataData
LWLMLWLM
Waveform ComparisonWaveform Comparisonbetween Data & RSG+LWLM between Data & RSG+LWLM
Am
pli
tud
eA
mp
litu
de
Time (ms)Time (ms)600600 24002400
DataData
RSG + LWLMRSG + LWLM
Elimination of RSG & LWLMElimination of RSG & LWLM
TimeTime (ms)(ms)
400400
25002500
Offset (m)Offset (m)00 32503250
Further Multiple AttenuationFurther Multiple Attenuation
TimeTime (ms)(ms)
400400
25002500
Offset (m)Offset (m)00 32503250
OutlineOutline
• IntroductionIntroduction
• TheoryTheory
• Synthetic experimentsSynthetic experiments
• Application to Unocal dataApplication to Unocal data
• ConclusionConclusion
Unocal field dataUnocal field data
TimeTime (ms)(ms)
600600
24002400
Offset (m)Offset (m)00 31753175
Inadequate RSG DecompositionInadequate RSG Decomposition
TimeTime (ms)(ms)
600600
24002400
Offset (m)Offset (m)00 31753175
Emulated LWLMEmulated LWLM
TimeTime (ms)(ms)
600600
24002400
Offset (m)Offset (m)00 31753175
Waveform comparisonWaveform comparisonbetween Data & Emulated LWLMbetween Data & Emulated LWLM
Am
pli
tud
Am
pli
tud
ee
Time (ms)Time (ms)14001400 24002400
DataData
LWLMLWLM
Attenuation of WLMAttenuation of WLM
TimeTime (ms)(ms)
600600
24002400
Offset (m)Offset (m)00 31753175
Attenuation of WLMAttenuation of WLM
Attenuation of WLMAttenuation of WLM
TimeTime (ms)(ms)
600600
24002400
Offset (m)Offset (m)00 31753175
Attenuation of WLMAttenuation of WLM
Subtracted WLMSubtracted WLM
TimeTime (ms)(ms)
600600
24002400
Offset (m)Offset (m)00 31753175
OutlineOutline
• IntroductionIntroduction
• TheoryTheory
• Synthetic experimentsSynthetic experiments
• Application to Unocal dataApplication to Unocal data
• ConclusionConclusion
ConclusionConclusion• Theoretically revives Berryhill and Wiggins Theoretically revives Berryhill and Wiggins methods for primary-preserving removal of one methods for primary-preserving removal of one kind of water-layer-multiples.kind of water-layer-multiples.
• Requirements are practically obtainable,Requirements are practically obtainable, and can be derived from seismic data.and can be derived from seismic data.
• Applicable to field data with approximations.Applicable to field data with approximations.
• Overcomes the Delft method by alleviating Overcomes the Delft method by alleviating acquisition requirements and the need to knowacquisition requirements and the need to know the source signature.the source signature.
Future WorkFuture Work
• Ghost decomposition for field data.Ghost decomposition for field data.
• 3D to 2D seismic data conversion.3D to 2D seismic data conversion.
• Multiple subtraction.Multiple subtraction.
ReferenceReference
1.1. Berryhill J.R. and Kim Y.C., 1986, Deep-water pegleg and Berryhill J.R. and Kim Y.C., 1986, Deep-water pegleg and multiples: emulation and suppression: Geophysics Vol. 51, multiples: emulation and suppression: Geophysics Vol. 51, 2177-2184.2177-2184.2.2. Wang Y., 1998, Comparison of multiple attenuation methods Wang Y., 1998, Comparison of multiple attenuation methods with least-squares migration filtering: UTAM 1998 annual with least-squares migration filtering: UTAM 1998 annual report, 311-342. report, 311-342. 2.2. Wiggins J.W., 1988, Attenuation of complex water-multiples Wiggins J.W., 1988, Attenuation of complex water-multiples by wave-equation-based prediction and subtraction: by wave-equation-based prediction and subtraction: Geophysics Vol.53 No.12, 1527-1539.Geophysics Vol.53 No.12, 1527-1539.
ThanksThanks
• 2003 members of UTAM for financial 2003 members of UTAM for financial support.support.
