Table Of ContentSeismic Amplitude
’
An Interpreter s Handbook
The oil and gas industries now routinely use seismic amplitudes in
exploration and production as they yield key information on lithology and
fluid fill, enablinginterpretation ofreservoir quality and likelihood of
hydrocarbon presence. The modernseismic interpreter must be able to
deployawholerangeofsophisticatedgeophysicaltechniques,suchasseismic
inversion,AVO (amplitude variation with offset),androck physics
modelling, aswell as integratinginformation fromother geophysical
techniques and well data.
This accessibleyet authoritative book provides a complete framework for
seismic amplitude interpretationand analysis, in apracticalmannerthat
allowseasyapplication–independentofanycommercialsoftwareproducts.
Springing from theauthors’extensive industry expertiseand experience of
delivering practicalcourses on thesubject, itguidesthe interpreter through
eachstep,introducingtechniqueswithpracticalobservationsandhelpingto
evaluate interpretationconfidence.
SeismicAmplitude is an invaluable day-to-day tool for graduate students
and industryprofessionals in geology, geophysics, petrophysics,reservoir
engineering, and allsubsurface disciplines making regular use ofseismic
data.
RobSimmis aSenior Geophysical Adviser for Cairn Energy PLC, and has
workedintheoilandgasindustrysince1985.Hespenttheearlypartofhis
careerworkingasaseismicinterpreterforBritishindependentoilcompanies
including Britoil, Tricentrol and Enterprise Oil. After working in
exploration,productionandfieldequityteams,DrSimmestablishedhisown
consultancy (Rock Physics Associates Ltd)in 1999,providing project and
training services to oil and gas companies.He runs an internationally
renowned training course on ‘The Essentials of Rock Physics for Seismic
Amplitude Interpretation’.
MikeBacon isa Principal Geoscientist forIkon ScienceLtd, having worked
for 30years in the oil industrywith Shell, Petro-Canada and Ikon Science.
Duringthattimehehasinterpretedseismicdatafromvariousbasinsaround
the world, with particularemphasis on extracting useful information from
seismicamplitudes.DrBaconhasservedasPublicationsOfficeroftheEAGE
(EuropeanAssociationofGeoscientistsandEngineers),chairingtheeditorial
board of the journal FirstBreak. He hasalso co-authored a number of
practical texts,including,with Rob Simm and Terry Redshaw,3-D Seismic
Interpretation (Cambridge University Press,2003).
“praisequote 1 tocome, dummy text;praise quote1to come, dummy text;
praise quote1to come, dummy text; praisequote 1to come,dummy text;
praise quote1to come, dummy text; praisequote 1to come,dummy text;
praise quote1to come, dummy text.”
- Reviewer 1, affiliation
“praisequote 2 tocome, dummy text;praise quote2to come, dummy text;
praise quote2to come, dummy text; praisequote 2to come,dummy text;
praise quote2to come, dummy text; praisequote 2to come,dummy text;
praise quote2to come, dummy text.”
- Reviewer 2, affiliation
Seismic Amplitude:
An Interpreter’s Handbook
Rob Simm
CairnEnergyPLC
Mike Bacon
IkonScienceLtd
UniversityPrintingHouse,Cambridgecb28bs,UnitedKingdom
PublishedintheUnitedStatesofAmericabyCambridgeUniversityPress,NewYork
CambridgeUniversityPressispartoftheUniversityofCambridge.
ItfurtherstheUniversity’smissionbydisseminatingknowledgeinthepursuitof
education,learningandresearchatthehighestinternationallevelsofexcellence.
www.cambridge.org
Informationonthistitle:www.cambridge.org/9781107011502
©RobSimmandMikeBacon2014
Thispublicationisincopyright.Subjecttostatutoryexception
andtotheprovisionsofrelevantcollectivelicensingagreements,
noreproductionofanypartmaytakeplacewithoutthewritten
permissionofCambridgeUniversityPress.
Firstpublished2014
PrintedintheUnitedKingdombyXXXX
AcataloguerecordforthispublicationisavailablefromtheBritishLibrary
LibraryofCongressCataloguinginPublicationdata
isbn 978-1-107-01150-2Hardback
CambridgeUniversityPresshasnoresponsibilityforthepersistenceoraccuracy
ofURLsforexternalorthird-partyinternetwebsitesreferredtointhispublication,
anddoesnotguaranteethatanycontentonsuchwebsitesis,orwillremain,
accurateorappropriate.
Contents
Preface ix
Acknowledgments x
1 Overview 1 4 Well toseismic ties 38
1.1 Introduction 1 4.1 Introduction 38
1.2 Philosophy,definitionsandscope 1 4.2 Logcalibration–depthtotime 38
1.3 Thepracticeofseismicrockphysics 2 4.2.1 Velocitiesandscale 38
4.2.2 Driftanalysisandcorrection 39
4.3 TheroleofVSPs 40
2 Fundamentals 3
4.4 Welltieapproachesusingsynthetics 43
2.1 Introduction 3
4.4.1 Welltiematchingtechnique 43
2.2 Seismicbasics 3
4.4.2 Adaptivetechnique 47
2.2.1 Seismicgeometry 3
4.5 Awelltieexample 47
2.2.2 Gathersandstacks 3
4.6 Welltieissues 50
2.3 Modellingforseismicinterpretation 6
4.6.1 Seismiccharacterandphaseambiguity 50
2.3.1 Theconvolutionalmodel,wavelets
4.6.2 Stretchandsqueeze 51
andpolarity 7
4.6.3 Sensecheckingandphaseperception 53
2.3.2 Isotropicandelasticrockproperties 10
4.6.4 Importanceoftieaccuracyinhorizonmapping 56
2.3.3 Offsetreflectivity 14
4.6.5 Understandingoffsetscaling 56
2.3.4 Typesofseismicmodels 17
4.6.6 Useofmatchingtechniquestomeasurean
2.3.5 Relatingseismicdatatomodels 19
improvingtie 57
3 Seismicwavelets and resolution 23 5 Rock properties and AVO 58
3.1 Introduction 23 5.1 Introduction 58
3.2 Seismicdata:bandwidthandphase 23 5.2 AVOresponsedescription 58
3.3 Zerophaseandminimumphase 24 5.2.1 PositiveornegativeAVOandthesignofthe
3.4 Changeofwaveletshapewithdepth 25 AVOgradient 58
3.5 Idealisedwavelets 28 5.2.2 AVOclassesandtheAVOplot 58
3.6 Waveletshapeandprocessing 29 5.2.3 IntroducingtheAVOcrossplot 59
3.6.1 Qcompensation 29 5.2.4 ExamplesofAVOresponses 59
3.6.2 Zerophasing 29 5.3 RockpropertycontrolsonAVO 61
3.6.3 Bandwidthimprovement 30 5.3.1 Rangesofparametersforcommonsedimentary
3.7 Resolution 32 rocks 61
3.7.1 Theproblemofinterference 32 5.3.2 Theroleofcompaction 62
3.7.2 Simplemodelsofinterference 32 5.3.3 Theeffectoffluidfill 63
3.7.3 Estimatingverticalresolutionfromseismic 33 5.3.4 Theeffectsofrockfabricandporegeometry 69
3.7.4 Theeffectofwaveletshapeonresolution 34 5.3.5 Bedthicknessandlayering 72
3.7.5 Lateralresolution 35 5.3.6 Theeffectsofpressure 77
3.8. Detectability 37 5.3.7 Anisotropy 83
v
Contents
5.4 Therockmodelanditsapplications 89 8.2.1 Theoreticalbounds 151
5.4.1 Examplesofrockmodelapplications 90 8.2.2 Empiricalmodels 152
5.5 Rockproperties,AVOreflectivityand 8.2.3 Gassmann’sequation 159
impedance 92 8.2.4 Minerals,fluidsandporosity 163
5.5.1 AVOprojections,coordinaterotationsand 8.2.5 Dryrockrelations 169
weightedstacks 93 8.2.6 Contactmodels 174
5.5.2 Angle-dependentimpedance 99 8.2.7 Inclusionmodels 176
5.5.3 Bandlimitedimpedance 103 8.3 Requirementsforarockphysicsstudy 178
5.6 SeismicnoiseandAVO 106 8.3.1 Datachecklist 178
8.3.2 Acousticlogs 179
6 Seismic processing issues 111 8.4 DataQCandlogedits 181
6.1 Introduction 111 8.4.1 Badholeeffects 181
6.2 Generalprocessingissues 112 8.4.2 VpandVsfromsonicwaveformanalysis 183
6.2.1 Initialamplitudecorrections 112 8.4.3 Logprediction 186
6.2.2 Long-wavelengthoverburden 8.4.4 Boreholeinvasion 188
effects 113 8.4.5 Soniccorrectionforanisotropyindeviated
6.2.3 Multipleremoval 114 wells 191
6.2.4 Migration 115 8.5 Practicalissuesinfluidsubstitution 192
6.2.5 Moveoutcorrection 115 8.5.1 Shaleysands 192
6.2.6 Finalscaling 116 8.5.2 Laminatedsands 194
6.2.7 Anglegathersandanglestacks 117 8.5.3 Lowporosityandpermeability
6.3 DataconditioningforAVOanalysis 118 sandstones 195
6.3.1 Spectralequalisation 119 8.6 Rockcharacterisationandmodelling
6.3.2 Residualmoveoutremoval 119 issues 196
6.3.3 Amplitudescalingwithoffset 121
6.3.4 Supergathers 123 9 Seismic trace inversion 198
6.3.5 Gradientestimationandnoisereduction 124 9.1 Introduction 198
9.2 Deterministicinversion 199
7 Amplitude andAVO interpretation 126 9.2.1 Recursiveinversion 199
7.1 Introduction 126 9.2.2 Sparsespikeinversion 199
7.2 AVOandamplitudescenarios 126 9.2.3 Model-basedinversion 200
7.2.1 ClassII/IIIhydrocarbonsandsandClassI 9.2.4 Inversionissues 204
watersands 127 9.2.5 InversionQCchecklist 209
7.2.2 ClassIIIhydrocarbonandwatersands 128 9.2.6 Bandlimitedvsbroadband 209
7.2.3 ClassIVhydrocarbonandwatersands 130 9.2.7 InversionandAVO 209
7.2.4 ClassIIphydrocarbonsands,ClassIwater 9.2.8 Issueswiththequantitativeinterpretationof
sands 131 deterministicinversions 213
7.2.5 ClassIhydrocarbonsands,ClassIwater 9.3 Stochasticinversion 214
sands 133
7.2.6 Multi-layeredreservoirs 134 10 Seismic amplitude applications 222
7.2.7 Hydrocarboncontacts 136 10.1 Introduction 222
7.2.8 Carbonates 145 10.2 Litho/fluid-faciesfromseismic 222
7.2.9 Fracturedreservoirs 147 10.3 Reservoirpropertiesfromseismic 224
10.3.1 Reservoirpropertiesfromdeterministic
8 Rock physics for seismic modelling 150 inversion 224
vi 8.1 Introduction 150 10.3.2 Simpleregression,calibrationand
8.2 Rockphysicsmodelsandrelations 151 uncertainty 226
Contents
10.3.3 Reservoirpropertymappingusinggeostatistical 10.6 Seismicamplitudetechnologyinreserves
techniques 229 estimation 252
10.3.4 Netpayestimationfromseismic 230
10.4 Time-lapseseismic 236
10.5 Amplitudesinprospectevaluation 247
10.5.1 Aninterpreter’sDHIchecklist 247 References 254
10.5.2 ABayesianapproachtoprospect Index 270
risking 248
10.5.3 Risking,statisticsandothersense
checks 250
vii
Preface
The past twenty years have witnessed significant The inter-disciplinary nature of ‘Seismic Rock
developments in the way that seismic data are used Physics’ presents a challenge for interpreters (both
in oil and gas exploration and production. Arguably old and new) who need to develop the appropriate
the most important has been the use of 3D seismic, knowledge and skills but it is equally challenging for
not only to map structures in detail but also to infer the asset team as a whole, who need to understand
reservoirpropertiesfromananalysisofseismicampli- how information derived from seismic might be
tude and other attributes. Improvements in seismic incorporatedintoprojectevaluations.Thisbookpro-
fidelity coupled with advances in the understanding vides a practical introduction to the subject and a
andapplicationofrockphysicshavemadequantitative frame of reference upon which to develop a more
description of the reservoir and risk evaluation based detailed appreciation. It is written with the seismic
on seismic amplitude not only a possibility but an interpreter in mind as well as students and other oil
expectationincertaingeologicalcontexts.Itisprobably and gas professionals. Mathematics is kept to a min-
noexaggerationtosaythattheinterpreterhasentereda imumwiththeexpressintentionofdemonstratingthe
newerainwhichrockphysicsisthemediumnotonly creative mind-set required for seismic interpretation.
fortheinterpretationofseismicamplitudebutalsofor To a large extent the book is complementary to
the integration of geology, geophysics, petrophysics other Cambridge University Press publications such
and reservoir engineering. For conventional oil and as 3-D Seismic Interpretation by Bacon et al. (2003),
gasreservoirs,thetechnologyhasreacheda sufficient ExplorationSeismologybySheriffandGeldart(1995),
stateofmaturitythatitispossibletodescribeeffective The Rock Physics Handbook by Mavko et al. (1998)
generic approaches to working with amplitudes, and and Quantitative Seismic Interpretation by Avseth
documentingthisisthepurposeofthisbook. et al.(2005).
ix
