strat analysis

SEQUENCE STRATIGRAPHY : Concept AND APPLICATION BDT

Department GeologyGadjah Mada University

SEQUENCE STRATIGRAPHY : CONCEPT AND APPLICATION

Compiled by :

Budianto Toha


Nevertheless, I persist in the claim that cratons, their margins,and their interior basins do not just lie there passively

waiting to be encroached upon by rising sea levelsor laid bare to erosion as sea levels fall.

Students and practitioners of sequence stratigraphy are,for the better or worse,

recorders and interpreters of tectonic evolution.

L.L. Sloss Forty years of sequence stratigraphyGeological Society of America Bulletin, v. 100. p. 1661-1665, Nov. 1988

Water flows downhillG.P. Allen

.and the sediment supply with it as well(adopted from Irfan Cibaj, June 2011)


Georges P. Allen spent 20 years studyingthe Mahakam delta area sedimentology.

We owe him the understanding ofsedimentary processes as well as

their consequences in reservoir geometry

Georges P. Allen, 25 May 1942 15 October 1998

(adopted from Irfan Cibaj, June 2011)


OBSERVASION INTERPRETATION PREDICTION

Geometry

Lithology

Fossil

Sedimentary structure

Paleocurrent

Depositional Environmentand Paleogeography

Location ,Geometry andEconomic Aspects

FACIES MODEL

FACIES ANALYSIS

points to remember


Sequence Stratigraphy and its application for HC exploration within ~ 8 hours ?? ..just like an effort to swallow a bigger prey than the mouth ..!!!!!

NEVER GIVE UP TRY and TRY AGAIN, YOULL SUCCEED AT LAST !!!!!


EXPLORATION CONCEPT


CONCEPTUAL MODEL OF PETROLEUM SYSTEMSOURCE ROCKS POTENTIAL:

1. SYN RIFT INTERVAL LESS DEEP SUB BASIN2. SYN RIFT AND POST RIFT INTERVAL INTERMEDIATE DEEP SUB BASIN3. SYN RIFT, POST RIFT AND BACK-ARC INTERVAL DEEP SUB BASIN

SYN RIFT IS THE BEST POTENSIAL SOURCE ROCKS PODS

RESERVOIR POTENTIAL: SYNRIFT : FLUVIAL, DELTAIC LACUSTRINE, LACUSTRINE BEACHPOST RIFT : FLUVIAL, DELTAIC, SHALLOW MARINE, CARBONATEBACK ARC : SHALLOW MARINE, DEEP WATER? AND FLUVIO-DELTAIC

POST RIFT INTERVAL IS THE BEST KNOWN RESERVOIR INTERVAL

SOURCE ROCKS POTENTIALTRAPS and SEAL / CAP ROCKS


It is concerned withall characters and attributes of rocks

as strata; and their interpretation in termsof mode of origin and

geologic history

STRATIGRAPHY :the science of rock strata


BASIN INFILLINGDYNAMICS SEDIMENTATIONSEQUENCE STRATIGRAPHY


Modified statement:

Law of Original Continuity: The original continuity of water-laid sedimentary strata is terminated only by pinching out against the basin of deposition, at the time of their deposition. (Anthony, loc.op.cit, p.83)

HORIZONTAL LATERAL CONTINUITY Steno, 1669)


Additional sediment supplywill be accommodated in the basinsuch as prograding or retrograding

fashion (side growth)(progradation/retrogradation)

PRINCIPAL OF LATERAL ACCRETIONSedimentary rocks are formed in

a depositional environment with initialsurface relatively inclined to the center

of the basin


PROGRADATION

RETROGRADATION

Actually . DEPOSITIONAL DYNAMICSAGGRADATION


DYNAMICS OF SEDIMENTATION

SL1 SL2

SL3

SL4SL5 SL6

SL7

EROSIONAL SURFACEPROGRADATIONRETROGRADATION

12 3

456677

8 99

10 11

121213


SEDIMENTARY FACIES AND ENVIRONMENT


SEDIMENTARY ENVIRONMENT AND FACIESA sedimentary environment is a part of earths surface which

is physically, chemically, and biologically distinct from adjacent terrains, e.g. deserts, river valleys, lake, deltas, lagoon, shallow marine ( Selley, 1985)

A sedimentary facies is a mass of sedimentary rocks which can be defined and distinguished from others by geometry, lithology, sedimentary sructures, paleocurrentpattern, and fossils (Selley, 1985)

PROCESS

PRODUCT


SEDIMENTARY FACIES :

PHYSICAL , CHEMICAL, and BIOLOGICAL ASPECTS OF DEPOSITIONAL ENVIRONMENT WITHIN SYNCHRONOUS INTERVAL

( After Selley , 1985 )

CAUSE EFFECTProcess

PhysicalChemicalBiological

SEDIMENTARYENVIRONMENT

ErosionalNon-depositionalDepositional SEDIMENTARYFACIES

GeometryLithologySedimentary

structuresPaleocurrentsFossils


DEPOSITIONAL FACIESAND ENVIRONMENT

(After Skinner and Porter, 1987 )

Various depositional environments occurring across the edge of a continental and the adjacent margin of an ocean basin


Dynamic of Sedimentation and

Sequence Stratigraphy

How sedimentary rock is accumulated Factors controlling process

Stratigraphic Record and its pattern


Stratigraphic record

Stratigraphic Record Dynamic of Sedimentation

( after Matthews, 1974)


Factors Controlling Sedimentation1. Subsidence2. Eustacy3. Sediment supply/ sediment flux4. (Climate)

Sediment flux Carbonate sedimentation Etc.

References :

Posamentier, H.W., Jervey, M.T. and Vail, P.R., 1988, Eustatic controls on clastic deposition I- conceptual framework, inWilgus, C.K. et al., (eds.) Sea level changes : an integrated approach. SEPM Spec. Publ. 42, p. 109-124.

_____________ and Vail P.R., 1988, Eustatic controls on clastic deposition II, in Wilgus, C.K. et al. (eds), Sea level changes :an integrated approach. SEPM Spec. Publ. 42, p. 125-154.


( After Allen, 1997)

FACTORS CONTROLLINGSHELF STRATIGRAPHIC PATTERNS


Dynamic Sedimentation

AccommodationSpace

The interaction of eustacy, subsidence, sediment supply, basin physiography, and climatelargerly control basin sedimentation. One or more variables may be dominant



Sed SupplyEustacyTectonics





constant

constant

constantconstant

constant

constant

constant

constant

PROGRADATION

PROGRADATION

REGRESSION

REGRESSION

CONSTANT SHORELINE

CONSTANT SHORELINE

TRANSGRESSION

AGRADATION

AGRADATION








Constant ( )

constantconstant

constant

constant

STARVED BASIN

TRANSGRESSION

Constant ( )

???

???

???etc..


MarineSequence Stratigraphy

Chronostratigarphy Stratal packages Controls of sedimentation

Accommodation space Tectonics Eustacy (sea level changes)

Basin geometry Physiography Sediment supply

Provenance Climate

Non-marineSequence Stratigraphy(Tectonostratigraphy)

Chronostratigarphy Stratal packages Controls of sedimentation

Accommodation space Tectonics

Basin geometry Topography Sediment supply

Provenance Climate

Time

Acc

om. S

pace

Initi

atio

nLo

cal S

aggi

ngC

limax

Reg

iona

l Fau

ltsC

oale

sce

Late

-rift

Pseu

do-

stas

is



Formation of superimposed deltaic cycles or sequences(after Allen and Chambers, 1998)


EUSTACY DEFINITION


The earths axis of rotation is inclined at an angle of 23.5o, which causes increasing seasonal variation in temperature and day lengths with increasing latitude. At the equinoxes the sun is directly overhead at the equator, and all parts of the earth receive 12 hours of light and 12 hours of darkness each day. At the summer solstice the sun is directly overhead at the Tropic of Cancer, and Artic Circle has 24 hours of continuous daylight, while all areas in the Southern Hemisphpere experience less than 12 hours of light everyday and the sun never rises below the Antartic Circle. At the winter solstice (not shown) the situation is reversed; incoming solar radiation is perpendicular to the erths surface at the Tropic of Carpicorn, and all areas in the Northern Hemisphere experience less than 12 hours of light each day ( Modified from Strahler ,1975)


Orbital variations and their force climatic changes and the formation of Milankovitchcycles


SEDIMENT ACCOMMODATION IS THE POTENTIAL SPACE AVAILABLE FOR SEDIMENT

TO ACCUMULATE

( After Allen, 1997 )

WHAT IS SEDIMENT ACCOMMODATION ?

on the shelf, accommodation is controlled byRELATIVE SEA LEVEL

in fluvial environments, accommodation is controlledby THE FLUVIAL EQUILIBRIUM PROFILE


Definition :

( After van Gorsel, 1987 )


Alluvial Coastal Plain and Fluvial Equilibrium Profile

( After Alen, 1999)


Accommodation in Fluvial Environment



Accommodation in Fluvial Environment



RELATION BETWEENACCOMMODATION AND FACIES PATTERNS

IN FLUVIAL AND SHELF DEPOSITS

In any given interval, if the rate and natureof sediment influx is constant, the sand / shale ratio

is inversely proportional to the ratio between :

rate of increase of accommodation and sediment supply


(After Allen, 1999)


Fluvial Stacking Pattern : an effect of increasing accommodation space


Effects of accommodation rates on fluvial aggradations


SB

SB

EFFECTS OF ACCOMMODATION RATES ON FLUVIAL AGGRADATION AND SAND/SHALE RATIO


SEQUENCE STRATIGRAPHY : Concept AND APPLICATION BDT(After Allen, 1999)

Effects of varying accommodation rates on coastaland shelf sediment patterns, and sand / shale ratio

A low rate of accommodation (i.e. RSL rise) on the shelf results in low rates of coastal plain aggradation, rapid shoreline progradation and high rate of sand amalgamation on the coastal plain.High rates of shelf aggradation (i.e. RSL rise) result in higher rates of coastal plain aggradationand decreased sand amalgamation


(rapid RSL rise, higher sed.supply)

Model Illustrating Prograding Delta with rapid increasing ofaccommodation space , and higher sediment supply


(slow RSL rise, higher sed.supply)

Model Illustrating Prograding Delta with slow increasing ofaccommodation space , and higher sediment supply


Facies Stacking Patterns :in a marine transition of depositional environment


Parasequence-stacking pattern in parasequence sets ; cross-section and well-log expression (Van Wagoner et al., 1991)


Can you define this outcrop stacking pattern ?

Multicolored layered sedimentary rocks in Capitol Reef National Park, Utah. (Skinner & Potter, 1987)


Can you define this outcrop stacking pattern ?

Cross-stratified sandstone, Utah. (Skinner & Potter, 1987)


STRATIGRAPHIC PATTERNS

REGRESSION and TRANGRESSION( increasing or decreasing Acc. Space vs Sed. Supply )

SEDIMENTARY CYCLES

EROSIONAL SURFACE(UNCONFORMITY ?) and /orDEPOSITIONAL SEQUENCES / FACIES


( Facies Succession )

(After Allen, 1999)


TRANSGRESSIONand

REGRESSION

( After van Gorsel, 1987 )


REGRESSIONS

THERE ARE TWO TYPES OF REGRESSIONS :

1. NORMAL REGRESSIONrelative sea level is constant or rising and

the coast migrates seaward because there is an overabundance of sediment supply with respect to accommodation

2. FORCED REGRESSIONSrelative sea level falls and as a result

the coastline migrates seaward regardless ofsediment supply



NORMALand FORCED

REGRESSIONS



SEDIMENTARY CYCLES

All shelf deposits are characterizedby cyclic sedimentation patterns

These cycles occur at several scales

These patterns are the result of cyclicpatterns of regression and transgressionwhich are formed by changes in relativesea level (accommodation space)



The stacking patterns of parasequences within a sequence.Each individual metre-scale cycle is produced by one high-frequencyrelative sea-level cycle, and the longer-term thickness pattern reflects thelower-frequency, longer-term change in accommodation space. The stacking patterns define the systems tracts of the sequence, as shown.

( from Tucker, 2003 )


An example of metre-scale cycles and their stacking pattern; asuccession consists of coarsening-upward units (thin arrows show the cycles), and they group into packages (sets) based on the increasing grain-size and thickness.

( from Tucker, 2003 )


Well-LogResponses

forBeach Parasequences

( from Van Wagoner et al., 1992)

SHALLOW-MARINEBEACH CYCLES :


Well-LogResponses

forDeltaic Parasequences


SHALLOW-MARINEDELTAIC CYCLES :


Stacking pattern ?

Flooding Surface ?

Sequence Boundaries ?

Maximum Flooding Surface ?

System Tracts ?

Potential reservoir ?

Additional data needed ?

EXERCISE :

SEQUENCE STRATIGRAPHY : Concept AND APPLICATION BDTSB

HST

TST

TST

LST

HST

PAL. DATA ?

PAL. DATA ?

PAL. DATA ?

MFS

fs


SEQUENCE DEFINITION

A RELATIVELY CONFORMABLE , GENETICALLYRELATED SUCCESSION OF PARASEQUENCES

AND PARASEQUENCE SETS BOUNDED BY UNCONFORMITY AND THEIR CORRELATIVE

CONFORMITIES

A SEQUENCE IS DEFINED BY THE PHYSICAL RELATIONSHIPS OF THE STRATA ALONE ;

NOT BYTHICKNESS , DURATION , OR INTERPRETATION OF GLOBAL OR

REGIONAL ORIGIN (i.e. scale independent)

( Van Wagoner , August 1994 )

It is used to provide a chronostratigraphic framework for the correlationand mapping of sedimentary facies and for stratigraphic prediction


Sequence stratigraphy Sequence stratigraphy conceptsconceptsDuration of stratigraphic cyclesDuration of stratigraphic cycles

1st order > 50 Megasequence / Wilson 2nd order 5 to 50 Supersequence / Sloss 3rd order 0.5 to 5 Sequence / Vail 4th order 0.1 to 0.5 Parasequence / Milankovitch 5th order 0.01 to 0.1 Parasequence / Milankovitch 6th order < 0.01 Parasequence / Milankovitch

1st through 3rd order sequences can be resolved on seismic

The Pematang Group is consistent with a 2nd order sequence(also known as a supersequence or a Sloss sequence)


SEQUENCE SYSTEM TRACTS* Their position within the sequence* Stacking patterns parasequences and parasequence sets

PARASEQUENCE :

* A relatively conformable succession of genetically relatedbeds or bed-sets , bounded by marine flooding surfaces andtheir correlative surfaces

* R sedimentation > R accommodation : coarsening / shallowingupward (mostly)

* Boundary : marine-flooding surface


CONCEPT OF LATERAL ACCRETION > DEPOSITIONAL PACKET > STRATAL ARCHITECTURE

1 100 Km SEQUENCESTRATIGRAPHY


Detailed Characteristics of Lamina , Laminaset , Bed , and Bedset(from Campbell , 1967)


Stratigraphic Components I


Stratal Units in Hierarchy : Definitions and Characteristics( from Van Wagoner et al., 1992)


Stratigraphic Components II


SCALE INSEDIMENTARY

SYSTEMSAfter Soegaard, 1994


SCALE INSEDIMENTARY

SYSTEMSAfter Soegaard, 1994


C. Low angle X-bedded sandstone, rests sharply on muddy-wavy-rippled siltstone. Sandstone is strongly X-bedded which becoming rippled to the top; fine tomedium grained; light to moderate brown; bioturbationare identified quite similar to rootlets, especially shown by hydrocarbon staining. This sandstone is interpreted as upper shoreface, or possibly channel (fluvial ?).GR reading of the underlying layer indicates of coarseningupward, which suggests possible offshore-bar or lower shoreface

B. Cross-bedded sandstone rapidly changes upwards into interbedded of very fine to fine grained light gray sandstone and muddy siltstone to silty-mudstone. A part of sandstone reveals wavy to current ripple structure, locally appearance of bioturbation and sediment deformation as well.This facies is interpreted as overbank sediments due tochannel avulsion, which may close to the active fluvial system,or possibly as backshore/mudflat lagoon

A. Varicolored of sandy mudstone, predominantly reddishbrown to purple with variation of grayish green, moderatebrown, gray and yellow. Massive, blocky, mottled reddish brown, some reveals subwaxy slickensided surfaces. This facies is interpreted as palaeosol developed in a lowrelief waterlogged flood plain setting.

B CA

B

Representative cores from X-Well Facies description and Interpretation


6764

6794

C

A

B

Core correlation to well-log

B


Facies Model of One Sequence ReservoirAnd its characteristics

( Toha et al., 1999 )


15 - 30

10 - 15

15 - 30

MB

TCF

AC1 / AC2

MS

LSH

Seal

Baffle

GR + FACIES Thickness100 101 102 103 104

K ( Permeability )

MSSealCarbonate

15 - 30

10 - 15

15 - 30

MS

MB

TCF

AC1 / AC2

MS

LSH

Seal

Seal

Baffle

Carbonate

GR + FACIES

100 101 102 103 104K ( Permeability )

Amalgamated Braided Channels :multistory , coarse-medium grained , erosive based , X-bedded sandstone ,isolated

LSH

MS

MB

TCF

AC2

AC1

Lenses Shale :local distribution (isolated)

Marine Shale :widespread lateral distribution

Prograding Mouth Bar :CU of fine to medium muddy/silty bioturbated sandstone. Cleaner , Bioturbation decreases, ripple laminated and highly cemented at the top.

Transgressive Channel Fill ( Estuarine ) :FU of medium to fine and silty bioturbated sandstone

Amalgamated Braided Channels :multistory , coarse grained , erosive based , X-bedded sandstone ,widespread lateral distribution

Core and Facies Model

15 - 30

10 - 15

15 - 30

MS

MB

TCF

AC1 / AC2

MS

LSH

Seal

Seal

Baffle

Carbonate

GR + FACIES

100 101 102 103 104

K ( Permeability )

Thickness

Thickness


STRATIGRAPHY & FACIES MODEL OF MINAS FIELD

MOUTH BAR

> 1000 mD AMALGAMATED BRAIDED CHANNELS

AMALGAMATED BRAIDED CHANNELS

PROGRADING MOUTH BAR

ISOLATED CHANNELS AND BARS

MFS (SEAL)

TRANSGRESIVE CHANNEL FILL (ESTUARINE)


MFS+CO3 (SEAL)

SB

10-1000 mD

10-1000 mD

100-1000 mD

AMALGAMATED BRAIDED CHANNELSSB

MFS (SEAL)

( Infill, Horizontal, Attic wells and Tertiary Target )

> 1000 mD

X

A1

A2

B1

B2

D

100-1000 mD

> 1000 mD

10-1000 mD

Potential bypassed Oil

MFS (SEAL)

GR Permeability ( K ) FACIES Former Name

TRANSGRESIVE CHANNEL FILL (ESTUARINE)



Sedimentological facies versus reservoir petrophysical classes

mudstone

Burrowedmudstone

tosiltstone

Schematic prograding mouth bar cross section

Thinbedded

burrowedsandstone

andmudstone

interbeddedclean

sandstoneand

mudstone

Laminatedsandstone

cleansandstonewith few

claydrappes

distal ProximalNon reservoir C B A



Lateral facies relationship and postulated core and well-log reponsesFor beach parasequence


Aerial view of the mouth bar 2 deposited in the delta frontunder 2 5 m of water depth. It emerges during the lowest tides.

The emerged part can reach many kilometers in extension.

Distal part of the mouth bar

Fine to mediumgrained sand

Bioturbatedsand

Silt shaleallternations

Shale siltallternations

Proximal part of the mouth bar

Fine to mediumgrained sand

Bioturbatedfine sand

Laminatedfine sands

Very fine sands

( after Cibaj, 2011 )


Coarse-grained channel fill

Fining upwardsgrain size

Sharp and erosive basalsurface of the channel

Coal bed

SEDIMENTOLOGY FOR GEOSCIENTISTSSEDIMENTOLOGY FOR GEOSCIENTISTSDistributaryDistributary channel as observed in outcropchannel as observed in outcrop

Lateral accretion

Coal bed

Coal bed



Tidal channel

Distributary channel

Distributary channels as observed in the modern Mahakam delta



EXAMPLE OF FACIES MAP

EXERCISE - DELTA


GR LLDNPHIRHOB

0

1

2

3

3.5

3.6

3.7

3.8

4

4D - 46A755

Type Log

5

4

3.8

3.7

3.6

3.5

3

2

1

0

SB

MFS

SB

MFS

SBMFS

MFS

Channel - Fill ( includes distributary channels & incised fluvial channel )Mouth BarsMudstone - Mainly Delta front to shelf

SCHEMATIC HIGH RESOLUTIONSTRATIGRAPHY FRAMEWORK

High Resolution Seq. Strat .Flooding Surfaces

Regional CSBSeq. Strat . Markers( 3rd Order )

No OrientationNo Scale

SB : Sequence BoundaryMFS : Maximum Flooding Surface

S t e p I : Ident ify 3rd Order Seq. St rat . MarkersIdent ify Facies Li t hology e.g. Channels, BarsIdent ify f looding SurfacesSubdivided int o Individual Parasequences

CORRELATION


SB

200G R

FEETM D TVDSS

LLD 0.48 0.09NPH IRHOB

2.5120000.2

?

0

1

2

3

3.5

3.6

3.7

3.8

4

?

200G R

FEETM D TVDSS

LLD 0.48 0.09NPH IRHOB

2.5120000.2

200G R

FEETM D TVDSS

LLD0.48 0.09NPH IRHOB

2.5120000.2

4D - 46A755

4D - 37746

4D - 38752

MFS

MFS

MFS

SB

ST EP 2 Cor relat e M ar ine Fl ood ing Sur f acesCor relat e FaciesM app ing w i t h in Chronost rat i g raph ic Un i t s

SW NE


Wells Log Correlation

RQP VS T U


SAND ISOPACHS

Section D

MOUTHBARSectionB

Section B

427

493

258 816888

886

811 839

443 844

335765

479

461

779 78590

444492

171

790336

780

822

743

825

736

748

65 798

807

45 805

451

767

769 BAR

836

810832

466 774

808

796771

801

905

1008

1004

1011

286

0 500 1000 meters

BAR

421

420 803

CHANNEL

65

CHANNEL

Zone of erosion byby overlying reservoir

N

407

809

847

754

CHANNEL

20

33 39 34

36

41

40

2343

2835

32

46

22

40

20

21

33

2017

4

14

12

2015 16

8

10

0

10

15

18

14

21 20

20

28

30

35

35

3320

12

4

9510

65

7

40 3342

3

2920

20

806

20

3318

20

15

10

2420

10

10

MOUTHBAR

< 10'

10' - 20'

< 20'

20' - 40'

> 40'

CHANNEL

812

10

838

40

40

10

SectionA

3 D

2 F2 D 2 E

4 E4 C 4 D

3 ECHANNEL

BAR

RESERVOIR M3-M3.5 ( UPPER )


SAND DEPOSITIONAL ENVIRONMENTS

905

Section D

MOUTHBARSection B

Section C

427

493

258 816888

812

886

811 839

844 847

335 754765

479

461

779 78590

444492

171

790336

780

822

743

825

748

65 798

807

45 805

451

767

769MOUTH BAR

838 836810

832

466 774

808

809

796771

801

1008

1004

1011

286

421

420 803

No sandstone

65

Section A

Erosive contactwith overlying reservoir

Fluvial/Distributary Channel

Delta Front/Mouth Bar

N

3 D

2 F2 D 2 E

4 E4 C 4 D

3 E

MOUTH BAR

CHANNEL

CHANNEL

CHANNEL

736

443

0 500 1000 meters

RESERVOIR M3-M3.5 ( UPPER )

Permeability TrendChannel

Perm

eabi

lity

Tren

dM

outh

Bar


STYLES OF CHRONO- vs LITHO-STRATIGRAPHIC CORRELATIONfor progradational parasequence set (Van Wagoner et al., 1992)


STYLES OF CHRONO- vs LITHO-STRATIGRAPHIC CORRELATIONfor retrogradational parasequence set (Van Wagoner et al., 1992)


APPLICATION EXAMPLE : WELLS CORRELATION, SANGATA FIELD

SUCCESS EXAMPLEFROM MINAS FIELD


END SLIDES FOR THE CLASS

THANK YOU !TERIMAKASIH !

MATUR NUWUN !

ADDITIONAL SLIDESFOR FURTHER DISCUSSION

IF NECESSARY AND TIMES ALLOWED

strat analysis

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