using 3d seismic attributes in reservoir characterization1041
TRANSCRIPT
Using 3-D Seismic Attributesin Reservoir CharacterizationUsing 3-D Seismic Attributesin Reservoir Characterization
Susan NissenGeophysical ConsultantMcLouth, KS
Susan NissenGeophysical ConsultantMcLouth, KS
Kansas Next Step 2007 Seminar: New Technology/Seismic/Seismic InKansas Next Step 2007 Seminar: New Technology/Seismic/Seismic InterpretationterpretationAugust 9, 2007August 9, 2007
Hays, KSHays, KS
OutlineOutline•• Brief overview of some reflection seismology basicsBrief overview of some reflection seismology basics
•• What are seismic attributes and what physical What are seismic attributes and what physical information can they provide?information can they provide?
•• Methods of interpreting attributes from 3Methods of interpreting attributes from 3--D seismic D seismic volumesvolumes
•• Reservoir Characterization ExamplesReservoir Characterization Examples–– Fault interpretation Fault interpretation –– PorosityPorosity–– Bed thickness estimationBed thickness estimation–– Fracture delineationFracture delineation
•• ConclusionsConclusions
The Seismic Reflection MethodThe Seismic Reflection Method
33--D seismic data volumeD seismic data volumeCMP gatherCMP gather
MoveoutMoveout, , stack, migratestack, migrate
CMP
Source
ρ1V1
ρ2V2
Receiver
Geophone (receiver)Geophone (receiver)Vibrator truck (source)Vibrator truck (source)
Figure Courtesy of Industrial Vehicles
Seismic Reflection InterpretationSeismic Reflection InterpretationUsually horizonUsually horizon--basedbased
HorizonHorizon -- the surface the surface separating two different separating two different rock layers; also, the rock layers; also, the reflection from this reflection from this surface.surface.
0.4
0.5
0.6
0.7
0.8
Trav
el ti
me
(sec
onds
)
ρ1V1
ρ2V2
ρ3V3
ρ4V4
Horizon 1Horizon 1
Dep
th
Horizon 2Horizon 2
Horizon 3Horizon 3
Seismic Applications in Petroleum ExplorationSeismic Applications in Petroleum Exploration
Structural analysisStructural analysis (1920s onward)(1920s onward)•• study of reflector geometrystudy of reflector geometry•• used to identify faults and used to identify faults and
locally high parts of formationslocally high parts of formations
deBruin et al. (2007)
Seismic sequence stratigraphySeismic sequence stratigraphy (1970s onward)(1970s onward)•• study of reflection sequences study of reflection sequences •• used to locate stratigraphic used to locate stratigraphic
traps and define the facies traps and define the facies framework of structural trapsframework of structural traps
Seismic attribute analysisSeismic attribute analysis (1970s onward)(1970s onward)•• study of seismic attributes study of seismic attributes •• provides information related to structure, provides information related to structure,
stratigraphy, and reservoir propertiesstratigraphy, and reservoir properties
What are Seismic Attributes?What are Seismic Attributes?
Any measurement Any measurement derivedderived from the from the seismic data is a seismic attribute.seismic data is a seismic attribute.
Seismic attributes typically provide Seismic attributes typically provide information relating to the information relating to the amplitudeamplitude, , shapeshape, and/or , and/or positionposition of the seismic of the seismic waveform.waveform.
Seismic attributes reveal features, Seismic attributes reveal features, relationships, and patterns in the relationships, and patterns in the seismic data that otherwise might not seismic data that otherwise might not be noticed.be noticed.
General classes of attributesGeneral classes of attributes
11--D attributes D attributes -- operate on a single stacked operate on a single stacked seismic traceseismic trace
22--D and 3D and 3--D attributes D attributes -- calculated using calculated using information from adjacent tracesinformation from adjacent traces
Families of Seismic AttributesFamilies of Seismic AttributesTime Attributes Time Attributes (1930s)(1930s) –– related to the vertical position related to the vertical position of the waveform in the seismic section (e.g., of the waveform in the seismic section (e.g., horizon horizon timetime picks, picks, isochronsisochrons))
Envelope:Envelope: A(t) = [qA(t) = [q22(t)+r(t)+r22(t)](t)]1/21/2
Instantaneous Phase:Instantaneous Phase: θθ(t) = tan(t) = tan--11[q(t)/r(t)][q(t)/r(t)]Instantaneous Frequency:Instantaneous Frequency: ωω(t)=(t)=ddθθ(t)/(t)/dtdt
q(t)
A(t)
r(t)
θ(t)
Complex Trace Attributes Complex Trace Attributes (1970s)(1970s) –– The seismic data The seismic data is treated as an analytic trace, is treated as an analytic trace, which contains both real and which contains both real and imaginary parts.imaginary parts. Various Various amplitudeamplitude, , phasephase, and , and frequencyfrequency attributes can be attributes can be calculated. calculated.
Taner et al. (1989)
Families of Seismic AttributesFamilies of Seismic AttributesWindow Attributes Window Attributes (1980s)(1980s) –– attributes which summarize attributes which summarize information from a vertical window of data.information from a vertical window of data.
Fourier Attributes Fourier Attributes (1990s)(1990s) –– frequency frequency domain attributes obtained through domain attributes obtained through Fourier analysis (e.g., Fourier analysis (e.g., spectral spectral decompositiondecomposition))
MultiMulti--trace Attributestrace Attributes (1990s)(1990s) -- attributes calculated attributes calculated using more than one input seismic trace, which provide using more than one input seismic trace, which provide quantitative information about lateral variations in the quantitative information about lateral variations in the seismic data (e.g., seismic data (e.g., coherencecoherence, , dip/azimuthdip/azimuth, , volumetric volumetric curvaturecurvature))
Definitions of selected attributes
Definitions of selected attributes
Envelope:Envelope: A(t) = [qA(t) = [q22(t)+r(t)+r22(t)](t)]1/21/2
Instantaneous Phase:Instantaneous Phase: θθ(t) = tan(t) = tan--11[q(t)/r(t)][q(t)/r(t)]Instantaneous Frequency:Instantaneous Frequency: ωω(t)=(t)=ddθθ(t)/dt(t)/dt
Instantaneous AttributesInstantaneous Attributes
q(t)
A(t)
r(t)
θ(t)
Taner et al. (1989)
Spectral DecompositionSpectral Decomposition
SingleSingletracetrace
All tracesAll traces
FF11
FF22
black = low amplitudeblack = low amplitudewhite = high amplitudewhite = high amplitude
analysisanalysiswindowwindow
3D Seismic Volume3D Seismic Volume
}Uses the Fourier transform to Uses the Fourier transform to calculate the amplitude calculate the amplitude spectrum of a short time spectrum of a short time window covering the zone of window covering the zone of interestinterest
The amplitude spectrum is The amplitude spectrum is tuned by the geologic units tuned by the geologic units within the analysis window, within the analysis window, so that units with different so that units with different rock properties and/or rock properties and/or thickness will exhibit different thickness will exhibit different amplitude responses.amplitude responses.
Seismic CoherenceSeismic Coherence
black = low coherenceblack = low coherencewhite = high coherencewhite = high coherence
fault = low coherencefault = low coherence
fault = low coherencefault = low coherence
3D Seismic Volume3D Seismic Volume
For each point in a 3D seismic volume, compare the waveformFor each point in a 3D seismic volume, compare the waveform
over a short vertical windowover a short vertical windowof adjacent traces (e.g., red trace compared to blue traces)of adjacent traces (e.g., red trace compared to blue traces)
Coherence CubeCoherence Cube
A measure of the traceA measure of the trace--toto--trace similarity of the seismic trace similarity of the seismic waveform within a small analysis windowwaveform within a small analysis window
Sigismondi and Soldo, 2003
May be computed at any azimuth about a point
Generally computed normal to tangent plane
Principal Curvatures (kmaxand kmin) can be combined to define other curvature attributes
Volumetric CurvatureVolumetric CurvatureCurvature describes how bent a surface is at a Curvature describes how bent a surface is at a particular point and is closely related to the second particular point and is closely related to the second derivative of the curve defining the surface.derivative of the curve defining the surface.
Volumetric curvature is computed for every point Volumetric curvature is computed for every point within a 3within a 3--D seismic volume.D seismic volume.
PositiveCurvature
ZeroCurvature
ZeroCurvature
DippingPlane
Anticline
Syncline
NegativeCurvature
Flat
Z
X
After Roberts, 2001
PositiveCurvature
ZeroCurvature
ZeroCurvature
DippingPlane
Anticline
Syncline
NegativeCurvature
Flat
Z
X
PositiveCurvature
ZeroCurvature
ZeroCurvature
DippingPlane
Anticline
Syncline
NegativeCurvature
Flat
Z
X
Z
X
After Roberts, 2001Curvature (k)=1/R
R
2-D 3-D
What physical information is provided by seismic attributes? What physical information is
provided by seismic attributes? EnvelopeEnvelope-- presence of gas (bright spots), presence of gas (bright spots), thinthin--bed tuning effects, lithology changesbed tuning effects, lithology changesPhase Phase –– lateral continuity of reflectors, lateral continuity of reflectors, bedding configurationsbedding configurationsFrequency Frequency –– bed thickness, presence of bed thickness, presence of hydrocarbons, fracture zoneshydrocarbons, fracture zonesSpectral Decomposition Spectral Decomposition –– bed thicknessbed thicknessCoherence, Volumetric Curvature Coherence, Volumetric Curvature –– faults, faults, fractures, lateral stratigraphic fractures, lateral stratigraphic discontinuitiesdiscontinuities
Methods of interpreting attributes from 3-D seismic volumes
Methods of interpreting attributes from 3-D seismic volumes
Identify spatial patterns/trends in attribute dataIdentify spatial patterns/trends in attribute data–– CrossCross--sectional view sectional view –– Map view (attributes extracted along horizon or from Map view (attributes extracted along horizon or from
zone of interest) zone of interest) –– 3D visualization3D visualization
Tie attributes to well control using statistical Tie attributes to well control using statistical methods (e.g., methods (e.g., crossplotscrossplots))Automatically analyze multiple attributes (with or Automatically analyze multiple attributes (with or without well control)without well control)–– GeostatisticsGeostatistics–– Principal component analysisPrincipal component analysis–– Cluster analysisCluster analysis–– Texture analysisTexture analysis
Reservoir CharacterizationExamples
Reservoir CharacterizationExamples
Fault Interpretation – Offshore TrinidadFault Interpretation – Offshore TrinidadSeismic Time SliceSeismic Time Slice Coherence SliceCoherence Slice
Complex Complex faulting faulting difficult to difficult to detect on detect on seismicseismic
Coherence Coherence shows shows lateral lateral continuity continuity of faultsof faults
Gersztenkorn et al., 1999
Limits of Porous Reservoir Limits of Porous Reservoir ----
Mississippian Dolomite ReservoirMississippian Dolomite ReservoirJudicaJudica FieldField
Ness and Gove Counties, KSNess and Gove Counties, KS
GR
Nt Phi Guard Res
20% O/W -1938
DO
LOM
ITE
LS
LS
Base Warsaw LS
OsagianSeries
MeramecianSeries
Spergen
Warsaw
Mis
siss
ippi
anSystem
Penn
.
?
Judicapay zone
Top Miss
After Dubois et al., 2003
Judica Field Stratigraphy
Judica 3-D seismic survey
Bhattacharya et al., 2004
ADry holes on structural Dry holes on structural
high due to low porosity high due to low porosity within reservoir intervalwithin reservoir interval
Base Warsaw LSTop Miss
0.80 s
0.85 s
A'A A'
Top Mississippian structure
Base Warsaw LS amplitude map
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
-18000 -16000 -14000 -12000 -10000 -8000 -6000 -4000
seismic amplitude - Base Warsaw LS horizon
phi-h
(por
osity
-ft)
Bhattacharya et al., 2004
Approximate porosityof reservoir interval: 5% 25%
Synthetic seismic section
Velocity model
Modeled variation in amplitude of Base Warsaw LS horizon due to increase in porosity of reservoir zone
-0.3
-0.25
-0.2
-0.15
Am
plitu
deB
ase
War
saw
LS
Top Mississippian Structure Map Base Warsaw LS Amplitude Map
Reservoir compartment Reservoir compartment mapped from 3mapped from 3--D seismic D seismic structure and amplitudesstructure and amplitudes
Bhattacharya et al., 2004
Judica 3-D attribute analysis results
Judica 3-D attribute analysis results
Seismic amplitude of the base of Warsaw LS Seismic amplitude of the base of Warsaw LS correlates with porositycorrelates with porosity--thickness of the thickness of the JudicaJudica pay zone, providing a method for pay zone, providing a method for discriminating between dry and productive discriminating between dry and productive wellswells
A combination of seismic structure and A combination of seismic structure and amplitude analysis allows us to better amplitude analysis allows us to better delineate reservoir compartment boundariesdelineate reservoir compartment boundaries
"Thin bed" thickness "Thin bed" thickness estimationestimation
----Upper CretaceousUpper Cretaceous “D” Sand“D” Sand
Sooner Unit, ColoradoSooner Unit, Colorado
“D” Sand Reservoir“D” Sand Reservoir
Upper CretaceousUpper CretaceousIncised valley fill Incised valley fill Fluvial and estuarine sedimentsFluvial and estuarine sediments
Cannon, 1998
"D" sand thickness from wells"D" sand thickness from wells
ObjectiveObjectiveDetermine “D” sand thickness between well control Determine “D” sand thickness between well control points.points.
10 ms10 ms
Sooner 3-D seismic survey“D” sand isochron map
Sooner 3-D seismic survey“D” sand isochron map
7 ms7 ms
Unfortunately….Unfortunately….Over most of the 3Over most of the 3--D survey D survey area, the “D” sand is below area, the “D” sand is below seismic resolution (a “thin seismic resolution (a “thin bed”).bed”).Below seismic resolution, Below seismic resolution, reflections from the top and reflections from the top and bottom of the sand maintain a bottom of the sand maintain a constant temporal separation, constant temporal separation, which is unrelated to the true which is unrelated to the true sand thickness. Amplitude, sand thickness. Amplitude, however, decreases with however, decreases with decreasing bed thickness.decreasing bed thickness.
Therefore….Therefore….EnvelopeEnvelope and and spectral spectral decompositiondecomposition, both related to , both related to amplitude, are likely to be amplitude, are likely to be better potential predictors of better potential predictors of “D” sand thickness“D” sand thickness
Two-way true thickness (ms)
Two-
way
app
aren
t thi
ckne
ss
AMPL
ITUD
E
THICKNESS
b/2TR
Max
imum
abs
olut
e am
plitu
deof
com
posi
te w
avel
et
2.0
1.0
0b/2
For our model wavelet (Ormsby 12/16-80/100):b/2 = tuning thickness = 7.9 ms (~ 53 ft)T = temporal resolution = 7.2 ms (~49 ft)R
25201510500
25
5
10
15
20
Maximum thickness of “D” Sand
1200012000
00
EnvelopeEnvelope-- extracted along top “D” sand horizonextracted along top “D” sand horizon
““D” sand thickness D” sand thickness contours from wellscontours from wells
Discrete Fourier component thin bed tuning analysis
Discrete Fourier component thin bed tuning analysis
After Partyka, 2001
ampl
it ude
10 Hz
20 Hz
30 Hz
40 Hz
temporal thickness (ms)0 5 10 15 20 25
Maximum thickness of "D" sand
envelope
Spectral DecompositionSpectral Decomposition-- 50 ms window centered on “D” sand50 ms window centered on “D” sand
60 Hz60 Hz50 Hz50 Hz 70 Hz70 Hz
20 Hz20 Hz 30 Hz30 Hz 40 Hz40 Hz
Am
plitu
deA
mpl
itude
00
0.80.8
0.80.8
00
Spectral Decomposition – 29 HzSpectral Decomposition – 29 Hz-- 50 ms window centered on “D” sand50 ms window centered on “D” sand
““D” sand thickness D” sand thickness contours from wellscontours from wells
Crossplots of attribute versus “D” sand thicknessCrossplots of attribute versus “D” sand thickness
Spectral Decomposition – 29 HzSpectral Decomposition – 29 Hz
IsochronIsochron
EnvelopeEnvelope
Fracture DelineationFracture Delineation----
Mississippian ReservoirMississippian ReservoirDickman FieldDickman Field
Ness County, KansasNess County, Kansas
Dickman Mississippian ReservoirDickman Mississippian ReservoirSubjacent to regional preSubjacent to regional pre--Pennsylvanian Pennsylvanian unconformity and karst unconformity and karst surface surface Composed of multiComposed of multi--layered layered shallow shelf carbonatesshallow shelf carbonatesProduction strongly Production strongly influenced by solutioninfluenced by solution--enhanced natural fracturesenhanced natural fracturesSupported by strong Supported by strong bottom water drivebottom water driveHigh waterHigh water--cut production cut production (>94%)(>94%)Seismic depth map of top Mississippian Seismic depth map of top Mississippian
(pre(pre--Penn unconformity surface)Penn unconformity surface)
0.5 mileC.I. = 10 ft
Shale-filled fractures intersected by horizontal well Ness County, KS
Shale-filled fractures intersected by horizontal well Ness County, KS
Karst-controlled10-100 ft intervalProvide a barrier to fluid flow
KarstKarst--controlledcontrolled1010--100 ft interval100 ft intervalProvide a barrier to Provide a barrier to fluid flowfluid flow
Carr et al., 2000
CoherenceCoherence
Seismic Attributes for Delineating Faults and Fractures
Seismic Attributes for Delineating Faults and Fractures
Volumetric CurvatureVolumetric Curvature
Calculated directly Calculated directly from seismic volumefrom seismic volumeExtracted along Extracted along interpreted horizoninterpreted horizon
Horizon CurvatureHorizon Curvature
Calculated from Calculated from interpreted horizoninterpreted horizon
0.5 mile
Volumetric Curvature – Gilmore City HorizonVolumetric Curvature – Gilmore City HorizonFrequency-Azimuth Rose Diagram
Length-Azimuth Rose Diagram
fault
NENE--trending lineamenttrending lineament
Interpreted shale- and debris-filled solution-enlarged fracture coincides
with NE-trending curvature lineament
Interpreted shale- and debris-filled solution-enlarged fracture coincides
with NE-trending curvature lineament
Thickness of karst zone in well versus distance to nearest NW and NE lineaments
Thickness of karst zone in well versus distance to nearest NW and NE lineaments
Thicker karst zonecloser to lineamentsNo relationship
0.5 mile
Oil production versus distance to nearest NW and NE lineaments
Oil production versus distance to nearest NW and NE lineaments
Increased oil production farther from lineaments
No relationship
A B
C
Water production versus distance to nearest NW and NE lineaments
Water production versus distance to nearest NW and NE lineaments
0.5 mile
No relationship
Increased water productionnear lineaments
A B
C
Dickman 3-D attribute analysis results
Dickman 3-D attribute analysis results
NENE--trending curvature lineaments appear to trending curvature lineaments appear to be barriers to fluid flow, and may represent be barriers to fluid flow, and may represent shaleshale--filled fractures.filled fractures.NWNW--trending curvature lineaments appear to trending curvature lineaments appear to represent open fractures, which serve as represent open fractures, which serve as conduits into the underlying aquifer.conduits into the underlying aquifer.Understanding the orientations of open and Understanding the orientations of open and filled fractures is an important prefilled fractures is an important pre--requisite requisite for effective reservoir management.for effective reservoir management.
General conclusions about attributesGeneral conclusions about attributesAttributes reveal information which is not readily Attributes reveal information which is not readily apparent in the raw seismic dataapparent in the raw seismic dataDozens of seismic attributes can be calculated, Dozens of seismic attributes can be calculated, some of which are more useful than otherssome of which are more useful than othersAttributes may be interpreted singly or using Attributes may be interpreted singly or using multimulti--attribute analysis toolsattribute analysis toolsDifferent attributes reflect different physical Different attributes reflect different physical properties of the underlying rock systemproperties of the underlying rock systemAttributes can aid in improving our Attributes can aid in improving our understanding of the reservoirunderstanding of the reservoirThe specific attributes to use in a reservoir The specific attributes to use in a reservoir characterization study will vary, depending on the characterization study will vary, depending on the type of reservoir and the problem being type of reservoir and the problem being addressedaddressed
AcknowledgmentsAcknowledgmentsTim Carr, Marty Dubois, and Tim Carr, Marty Dubois, and SaibalSaibal Bhattacharya, Bhattacharya, Kansas Geological SurveyKansas Geological SurveyKurt Kurt MarfurtMarfurt and Chuck Blumentritt, and Chuck Blumentritt, University of University of HoustonHoustonMull Drilling Company, Inc.Mull Drilling Company, Inc.Grand Mesa Operating Company Grand Mesa Operating Company Seismic MicroSeismic Micro--Technology, Inc. Technology, Inc. IHS, Inc.IHS, Inc.U. S. Department of EnergyU. S. Department of Energy