seismic sequence analysis geol 755: basin analysis...

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Taken From: Christopher G St. C. Kendall, Univ. South Carolina SequenceStratigrapy Web, http://strata.geol.sc.edu/seismic.html

John N. Louie, Presenter

Seismic Stratigraphy BasicsReflector Terminations

Sequence Boundary IdentificationSeismic Sequence Analysis Procedure

Example

Geol 755: Basin AnalysisGeol 755: Basin AnalysisGeophysics Week 4.5Geophysics Week 4.5


Seismic Sequence AnalysisSeismic Sequence Analysis

Objective: Define the genetic reflection packagesObjective: Define the genetic reflection packagesthat that envelope envelope seismic sequences seismic sequences and and systemssystemstracts.tracts.

These bounding discontinuities are identified onThese bounding discontinuities are identified onthe basis of reflection termination patterns andthe basis of reflection termination patterns andtheir continuity.their continuity.

ReferencesReferences Vail, P. R., 1987, Seismic Vail, P. R., 1987, Seismic stratigraphy stratigraphy interpretation procedure, in Bally, A.W. (ed.), Atlas ofinterpretation procedure, in Bally, A.W. (ed.), Atlas of

seismic seismic stratigraphystratigraphy: AAPG Studies in Geology No. 27, : AAPG Studies in Geology No. 27, VolVol. 1, p. 1-10.. 1, p. 1-10. Boggs, S. Boggs, S. JrJr., 2001, Principles of ., 2001, Principles of Sedimentology Sedimentology and and stratigraphystratigraphy, 3rd Ed., Prentice-Hall, Inc.,, 3rd Ed., Prentice-Hall, Inc.,

New Jersey, 726 p.New Jersey, 726 p.


Seismic Sequence AnalysisSeismic Sequence Analysis Boundaries are defined on a seismic line byBoundaries are defined on a seismic line by

identifying the termination of seismic reflectors atidentifying the termination of seismic reflectors atthe discontinuity surfaces. Terminations occur:the discontinuity surfaces. Terminations occur:

Below a discontinuity and the definition of the upperBelow a discontinuity and the definition of the uppersequence boundary. Examples of this include:sequence boundary. Examples of this include:1.1. ToplapToplap2.2. TruncationTruncation

Above a discontinuity and the definition of the lowerAbove a discontinuity and the definition of the lowersequence boundary:sequence boundary:1.1. OnlapOnlap2.2. DownlapDownlap

ReferencesReferences Vail, P. R., 1987, Seismic Vail, P. R., 1987, Seismic stratigraphy stratigraphy interpretation procedure, in Bally, A.W. (ed.), Atlas ofinterpretation procedure, in Bally, A.W. (ed.), Atlas of

seismic seismic stratigraphystratigraphy: AAPG Studies in Geology No. 27, : AAPG Studies in Geology No. 27, VolVol. 1, p. 1-10.. 1, p. 1-10. Boggs, S. Boggs, S. JrJr., 2001, Principles of ., 2001, Principles of Sedimentology Sedimentology and and stratigraphystratigraphy, 3rd Ed., Prentice-Hall, Inc.,, 3rd Ed., Prentice-Hall, Inc.,

New Jersey, 726 p.New Jersey, 726 p.


Seismic Sequence AnalysisSeismic Sequence Analysis ToplapToplap: : Termination of strata against anTermination of strata against an

overlying surface mainly as a result ofoverlying surface mainly as a result ofnondeposition nondeposition (sedimentary bypassing) with(sedimentary bypassing) withperhaps only minor erosion.perhaps only minor erosion.

ReferencesReferences Mitchum JrMitchum Jr., R.M., 1977. Seismic ., R.M., 1977. Seismic stratigraphy stratigraphy and global changes of sea level. Part 11: glossary of termsand global changes of sea level. Part 11: glossary of terms

used in seismic used in seismic stratigraphystratigraphy. In: Payton, C.E. (Ed.), Seismic . In: Payton, C.E. (Ed.), Seismic StratigraphyStratigraphy––––Applications Applications to Hydrocarbonto HydrocarbonExploration, Exploration, volvol. 26. A.A.P.G. Memoir, pp. 205. 26. A.A.P.G. Memoir, pp. 205––212.212.

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Seismic Sequence AnalysisSeismic Sequence Analysis Truncation: Truncation: Termination of strata or seismic reflectionsTermination of strata or seismic reflections

interpreted as strata along an unconformity surface dueinterpreted as strata along an unconformity surface dueto post-depositional to post-depositional erosional erosional or structural effects.or structural effects.

This implies the deposition of strata and their subsequent tiltingThis implies the deposition of strata and their subsequent tiltingand removal along an unconformity surface.and removal along an unconformity surface.

This termination is the most reliable top-discordant criterion of aThis termination is the most reliable top-discordant criterion of asequence boundary.sequence boundary.

Such truncation can also be caused by termination against anSuch truncation can also be caused by termination against aneerosional rosional surface, as for instance a channel.surface, as for instance a channel.

ReferencesReferences Mitchum JrMitchum Jr., R.M., 1977. Seismic ., R.M., 1977. Seismic stratigraphy stratigraphy and global changes of sea level. Part 11: glossary of terms used in seismicand global changes of sea level. Part 11: glossary of terms used in seismic

stratigraphystratigraphy. In: Payton, C.E. (Ed.), Seismic . In: Payton, C.E. (Ed.), Seismic StratigraphyStratigraphy––––Applications Applications to Hydrocarbon Exploration, to Hydrocarbon Exploration, volvol. 26. A.A.P.G. Memoir, pp.. 26. A.A.P.G. Memoir, pp.205205––212.212.


Seismic Sequence AnalysisSeismic Sequence Analysis OnlapOnlap: A base-discordant relationship in which initially: A base-discordant relationship in which initially

horizontal strata progressively terminate against anhorizontal strata progressively terminate against aninitially inclined surface, or in which initially inclined stratainitially inclined surface, or in which initially inclined strataterminate progressively terminate progressively updip updip against a surface ofagainst a surface ofgreater initial inclination.greater initial inclination.

ReferencesReferences Mitchum JrMitchum Jr., R.M., 1977. Seismic ., R.M., 1977. Seismic stratigraphy stratigraphy and global changes of sea level. Part 11: glossary of terms used in seismic and global changes of sea level. Part 11: glossary of terms used in seismic stratigraphystratigraphy. In: Payton,. In: Payton,

C.E. (Ed.), Seismic C.E. (Ed.), Seismic StratigraphyStratigraphy––––Applications Applications to Hydrocarbon Exploration, to Hydrocarbon Exploration, volvol. 26. A.A.P.G. Memoir, pp. 205. 26. A.A.P.G. Memoir, pp. 205––212.212.


Seismic Sequence AnalysisSeismic Sequence Analysis DownlapDownlap: a relationship in which seismic: a relationship in which seismic

reflections of inclined strata terminate reflections of inclined strata terminate downdipdowndipagainst an inclined or horizontal surface.against an inclined or horizontal surface.Examples of Examples of downlap downlap surfaces include a topsurfaces include a topbasin floor fan surface, a top slope fan surface,basin floor fan surface, a top slope fan surface,and a maximum flooding surface.and a maximum flooding surface.

ReferencesReferences Mitchum JrMitchum Jr., R.M., 1977. Seismic ., R.M., 1977. Seismic stratigraphy stratigraphy and global changes of sea level. Part 11: glossary of terms used in seismic and global changes of sea level. Part 11: glossary of terms used in seismic stratigraphystratigraphy. In: Payton, C.E. (Ed.),. In: Payton, C.E. (Ed.),

Seismic Seismic StratigraphyStratigraphy––––Applications Applications to Hydrocarbon Exploration, to Hydrocarbon Exploration, volvol. 26. A.A.P.G. Memoir, pp. 205. 26. A.A.P.G. Memoir, pp. 205––212.212.


Seismic Sequence AnalysisSeismic Sequence Analysis Note: If Note: If onlap onlap cannot be distinguished fromcannot be distinguished from

downlap downlap because of subsequencebecause of subsequencedeformation, the term deformation, the term baselapbaselap is used.is used.

ReferencesReferences Mitchum JrMitchum Jr., R.M., 1977. Seismic ., R.M., 1977. Seismic stratigraphy stratigraphy and global changes of sea level. Part 11: glossary of terms used in seismic and global changes of sea level. Part 11: glossary of terms used in seismic stratigraphystratigraphy. In: Payton, C.E. (Ed.),. In: Payton, C.E. (Ed.),

Seismic Seismic StratigraphyStratigraphy––––Applications Applications to Hydrocarbon Exploration, to Hydrocarbon Exploration, volvol. 26. A.A.P.G. Memoir, pp. 205. 26. A.A.P.G. Memoir, pp. 205––212.212.

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Seismic Sequence AnalysisSeismic Sequence Analysis Recommended procedures for performingRecommended procedures for performing

seismic sequence analysis include:seismic sequence analysis include: Identifying the unconformities in the area of interest.Identifying the unconformities in the area of interest.

Unconformities are recognized as surfaces onto whichUnconformities are recognized as surfaces onto whichreflectors converge.reflectors converge.

Mark these terminations with arrows.Mark these terminations with arrows. Draw the unconformity surface between the Draw the unconformity surface between the onlappingonlapping

and and downlapping downlapping reflections above; and the truncatingreflections above; and the truncatingand and toplapping toplapping reflections below.reflections below.

Extend the unconformity surface over the completeExtend the unconformity surface over the completesection. If the boundary becomes conformable, tracesection. If the boundary becomes conformable, traceits position across the section by visually correlatingits position across the section by visually correlatingthe reflections.the reflections.

ReferencesReferences Vail, P. R., 1987, Seismic Vail, P. R., 1987, Seismic stratigraphy stratigraphy interpretation procedure, in Bally, A.W. (ed.), Atlas of seismic interpretation procedure, in Bally, A.W. (ed.), Atlas of seismic stratigraphystratigraphy: AAPG Studies in: AAPG Studies in

Geology No. 27, Geology No. 27, VolVol. 1, p. 1-10.. 1, p. 1-10. Boggs, S. Boggs, S. JrJr., 2001, Principles of ., 2001, Principles of Sedimentology Sedimentology and and stratigraphystratigraphy, 3rd Ed., Prentice-Hall, Inc., New Jersey, 726 p., 3rd Ed., Prentice-Hall, Inc., New Jersey, 726 p.


Seismic Sequence AnalysisSeismic Sequence Analysis Recommended procedures for performingRecommended procedures for performing

seismic sequence analysis (cont.):seismic sequence analysis (cont.): Continue identifying the unconformities on all theContinue identifying the unconformities on all the

remaining seismic sections for the basin.remaining seismic sections for the basin. Make sure the interpretation ties correctly among allMake sure the interpretation ties correctly among all

the lines.the lines. Identify the type of unconformity:Identify the type of unconformity:

•• Sequence boundary: this is characterized by regional Sequence boundary: this is characterized by regional onlaponlapabove and truncation below.above and truncation below.

•• Downlap Downlap surface: this is characterized by regional surface: this is characterized by regional downlapdownlap..

ReferencesReferences Vail, P. R., 1987, Seismic Vail, P. R., 1987, Seismic stratigraphy stratigraphy interpretation procedure, in Bally, A.W. (ed.), Atlas of seismicinterpretation procedure, in Bally, A.W. (ed.), Atlas of seismic

stratigraphystratigraphy: AAPG Studies in Geology No. 27, : AAPG Studies in Geology No. 27, VolVol. 1, p. 1-10.. 1, p. 1-10. Boggs, S. Boggs, S. JrJr., 2001, Principles of ., 2001, Principles of Sedimentology Sedimentology and and stratigraphystratigraphy, 3rd Ed., Prentice-Hall, Inc., New Jersey,, 3rd Ed., Prentice-Hall, Inc., New Jersey,

726 p.726 p.


Seismic Sequence AnalysisSeismic Sequence Analysis Recommended color codes:Recommended color codes:

RedRed: Reflection patterns and reflection terminations.: Reflection patterns and reflection terminations.

GreenGreen: : Downlap Downlap surfacessurfaces

BlueBlue: : Transgressive Transgressive surfacessurfaces

Other colorsOther colors: Sequence boundaries: Sequence boundaries

If using only black and white:If using only black and white: Thin solid lines: Reflection Thin solid lines: Reflection pattenspattens Thicker solid lines: Sequence boundariesThicker solid lines: Sequence boundaries Dashed lines: Dashed lines: Downlap Downlap surfacessurfaces Dotted lines: Dotted lines: Transgressive Transgressive surfacessurfaces


Seismic Sequence AnalysisSeismic Sequence Analysis

seismic sequence analysis geol 755: basin analysis...

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