地震沉積學多媒體

1、Seismic Sedimentology4. Seismihologya.b.c.d.e.ConceptLithology-impedance relationship Seismic inversionAVOSeismic attributesWhat is Seismic InversionAny process that recovers earth mfrom seismic dataStrictly speaking, formulated inversion by minimizing an error function for the best fitting between

2、real data and syntheticsStratigraphic/statistic inversion is not an inversion instrict meaning (Monte Carlo style forward ming)Generally speaking, seismic interpretation and attribute analysis are also inversionsCopyright 2014 Dr Hongliu Zeng2Types of Seismic InversionRecursive inversion Colored inv

3、ersion Sparse-spike inversionGeneralized linear inversion Statistical inversionSpectral inversionCopyright 2014 Dr Hongliu Zeng3Generalized linear inversion(Least squares, iterative method, Hampson-Russell)r = (WTW)-1WTS - r0Correction (solution)Initial reflectivitymSeismic dataWavelet4Concept of In

4、versionForward mingImp logWaveletSeismic traceInversionConcept of InversionUnknown earthGuess mSyntheticCompare to dataInversionSeismic inversionSeismicInverted AITrue AIDrHongliu Zeng7Copyrighted byProblems of Seismic InversionUnderdeterminedness of thin-bed inversion: cannot solve thickness and im

5、pedance at the same timeDestroy waveform: compromise thin-bed detectionCopyright 2014 Dr Hongliu Zeng8Uncertainty of Thin-bed InversionSeismic(90-degree Ricker)InversionAI<4/lNon-uniqueness of inversionSynthetic (red)Seismic (black)Error (blue)Inversion (red)Ground Truth (black)Inversion 1Inversi

6、on 2Inversion 3Inversion 4DrHongliu Zeng10Copyrighted bySeismic inversion: still usefulInversion removes/reduces wavelet effect, equivalent to 90° phasing反演相當于90°相位化Give interpreters a sense of geologic sectionIf doing right, inversion may improve resolution正確的反演可分辨率CopyrightedbyDrHongliu

7、Zeng11Use wells (a priori m inversion) to improve1-52 Hz8-52 Hz(Hill, 2005)Copyrighted byZengl/12DrHongliu12Seismic Sedimentology4. Seismihologya. Conceptb. Lithology-impedance relationshipc. Seismic inversiond. Amplitude vs. Offset (AVO)e. Seismic attributesWhat is AVOZoeppritzs (1919) equations: p

8、artition of P- and S-wave energies when a plane wave propagates on an acoustic impedance contrastDR. Hongliu ZengCopyright ProtectedWhat is AVOAki and Richards (1980) approximation: p-wave reflection coefficient (Rpp) varies with incidence angle ():Rp = normal incidence p-wave reflectionB = AVO grad

9、ientDR. Hongliu ZengCopyright ProtectedWhat is AVOWiggins. show that for Vp/Vs ratios around 2, the AVOgradient is given by:Rp = normal incidence p-wave reflection coefficientRs = s-wave reflection coefficientAVO makes it possible to use new, s-wave informationin seismihologyDR. Hongliu ZengCopyrigh

10、t ProtectedWhy AVO is useful in lithology prediction?(Castagna, 1993)Different lithologies (e.g., sand, shale, gas sand) are characterized by different Vp/Vs, although they may have similar Vp (impedance)DR. Hongliu ZengCopyright ProtectedVp/Vs or other constants (attributes)?DR. Hongliu ZengCopyrig

11、ht ProtectedIn same cases, impedance is not good enough(Liu., 2013)DR. Hongliu ZengCopyright ProtectedAVO interpretation of lithology: case 1(Liu., 2013)DR. Hongliu ZengCopyright ProtectedAVO interpretation of lithology: case 2(Hilterman., 1998)DR. Hongliu ZengCopyright ProtectedSeismic Sedimentolog

12、y4. Seismihologya. Conceptb. Lithology-impedance relationshipc. Seismic inversiond. Amplitude vs. Offset (AVO)e. Seismic attributesConcept of Seismic AttributesSpecific measurements of geometric, kinematic, dynamic, or statistical features derived from seismic data從學特征資料中測量的幾何動學、動力學或統(tǒng)計- Chen and Sid

13、ney, 1997CopyrightedbyDrHongliu Zeng23Classification of Seismic Attributes(Brown, 1996)CopyrightedbyDrHongliu Zeng24Classification of Seismic Attributes(Chen and Sidney, 1997)CopyrightedbyDrHongliu Zeng25Classification of Seismic Attributes(Chen and Sidney, 1997)CopbyDr26Classification of Seismic At

14、tributes (Simplified and practical)DynamicAmplitude Instantaneous amplitude Instantaneous frequency Instantaneous phaseGeometric (texture)Edge detection 邊界檢測Coherency (continuity)相干Curvature/dip/azimuth曲率/傾角/方位Statistical (window, max/min, etc.)Attribute from attributesCopyrightedbyDrHongliu Zeng27I

15、nstantaneous AttributesF(t)h(t)g(t)(from Taner., 1979)F(t) = g(t) + j h(t) = A(t)exp j r(t)CopyrightedbyDrHongliu Zeng28Instantaneous AttributesA(t) instantaneous amplitudeg(t)(t) instantaneous phasef(t) = (t)/dt instantaneous freqg(t) = A(t) cos (t)(from Taner., 1979)CopyrightedbyDrHongliu Zeng29In

16、stantaneous Amplitude (Wedge)Zero phase90-degree phasel/4l/2l/4l/2llHighlowCopyrightedbyDrHongliu Zeng30Instantaneous Phase (Wedge)Zero phase90-degree phase090180(-180)270(-90)360(0)090180(-180)270(-90)360(0)l/4l/2l/4l/2ll1800CopyrightedbyDrHongliu Zeng31-180Instantaneous Frequency (Wedge)Zero phase

17、90-degree phasel/4l/2l/4l/2ll64 Hz0CopyrightedbyDrHongliu Zeng32Inst. Amplitude as Function of Thickness and Frequency8070605040302010060504030Frequency (Hz)200510010(ms)15Thickness2001020 304050607080Inst. AmplitudeInst. Frequency as Function of Thickness and Frequency6050403020100-10-20-3060504030

18、Frequency(Hz)20051010(ms)15Thickness20-30 -20 -10 0102030 4050Inst. FrequencyInst. Phase as Function of Thickness and Frequency6050403020Frequency(Hz)1010s (ms)1520110 120 130 140 150 160 170Inst. PhaseApplication of Seismic Attributes in Facies AnalysisInstantaneous amplitude Instantaneous frequenc

19、y Instantaneous phaseEdge detection/coherence (continuity)OthersCopyrightedbyDrHongliu Zeng36Application of Seismic Attributes in Facies Analysis (Amplitude)CopyrightedbyDrHongliu Zeng37Application of Seismic Attributes in Facies Analysis (Inst. Amplitude)CopyrightedbyDrHongliu Zeng38Application of

20、Seismic Attributes in Facies Analysis (Inst. Phase)CopyrightedbyDrHongliu Zeng39Application of Seismic Attributes in Facies Analysis (Inst. Frequency)CopyrightedbyDrHongliu Zeng40Application of Seismic Attributes in Facies Analysis (Edge Detection)CopyrightedbyDrHongliu Zeng41Application of Seismic

21、Attributes in Facies Analysis (Continuity)CopyrightedbyDrHongliu Zeng42SummaryAll dynamic attributes show some value in facies imaging, with amplitude remained as interpreters first choiceGeometric attributes (e.g., coherence) may make boundaries of a channel visually more striking, but are less sen

22、sitive to thin bedsCopyrightedbyDrHongliu Zeng43What Control Attributes and How to Select A Right One?Dynamic attributes are controlled by seismic frequency and phase. As a result, instantaneous attributes are basic and most important seismic attributes.Many attributes may be valuable for facies ana

23、lysis. However, useful attributes may vary with data and area. Experiences and trial-and-error are the best “weapon”.A attribute must be tied to geology to be useful. Number game is waste of time.CopyrightedbyDrHongliu Zeng44Case study(South Marsh Island, GOM, Chopra and Marfurt, 2007)AmplitudeCoher

24、enceCopyrightedbyDrHongliu Zeng45Case study(South Marsh Island, GOM, Chopra and Marfurt, 2007)CurvatureCopyrightedbyDrHongliuZeng46Case study(South Marsh Island, GOM, Chopra and Marfurt, 2007)Spectral componentsCopyrightedbyDrHongliu Zeng47FrequencyCase study(South Marsh Island, GOM, Chopra and Marf

25、urt, 2007)Amplitude + peak frequencyCopyrightedbyDrHongliu Zeng48Multi-attribute Analysisto Predict Reservoir PropertiesMulti-variable regressionNeural NetworksCopyrightedbyDrHongliuZeng49Before You Do Attribute AnalysisWells correctly tied to seismic90 phase seismic data recommendedProperties of in

26、terest at wells (I, f, h.) calculatedRock relationship predicted (warning: Type B data may need much more effort)CopyrightedbyDrHongliu Zeng50Multiattribute RegressionObservation I: Many seismic attributes (especially dynamic attributes) are related to rock parameters (I, f, h.)Observation II: Singl

27、e seismic attribute is at most moderately correlated to rock parameters (r=0.1-0.6)Observation III: Multiattribute regression may significantly improve rock parameter prediction (r up to 0.8)CopyrightedbyDrHongliu Zeng512D Attribute Analysis: DataTubbAboCopyrightedbyDrHongliu Zeng52Porosity Map from

28、 Well Logs0Porosity10CopyrightedbyDrHongliu Zeng53Porosity vs. Amplitude (Original Data)100.0y = 25.1 + 4.3512x R= 0.5182480.060.040.020.00.0024681012PHIT (average)AmplitudePorosity from Attribute Analysis (general: n x m)+ b12A12+ + b1mA1m+ + b2mA2mb11 A1+b21A2 + b22A22.f =+ bn2An2+ + bnmAnm+bn1An+

29、b0Porosity from Attribute Analysis (Abo: 3 x 4)original 0 - 400 - 55b12A12 b22A22 b32A32b13A13 b23A22 b33A32b14A14 b24A24 b34A34b11A1+b21A2+b31A3+b0+f =Porosity from Attribute Analysis (53 Wells, 3 Attributes)12.010.0y = 2.7401 + 0.46069x R= 0.680168.06.04.02.00.0024681012porosity from PHIT logPoros

30、ity from attributesAmplitude Map (Original Data)-+CopyrightedbyDrHongliu Zeng58Porosity from Attribute Analysis80CopyrightedbyDrHongliu Zeng59Porosity from Attribute Analysis with Production as BubblesCopyrightedbyDrHongliu Zeng60Amplitude Map (Original) with Production as BubblesCopyrightedbyDrHongliu Zeng61