ANALISA STRATIGRAFI

PERKEMBANGAN STRATIGRAFI

Th 80 - an ---.EXXON EXPLORATION RESEARCH LABORATORY :mengeluarkan KONSEP & TEKNIK tentang SEQUENCESTRATIGRAPHY

SEQ.STRATIGRAPHY merupakan hasil akhir dari SEISMICSTRATIGRAPHY (Mitchum, 1977)

Th. 1988: Konsep Seq. Strat. terbit pertama kali dalam SEPMSpecial Publication No. 42 (Wilgus et al, 1988) yang merupakanREFERENSI STANDAR : " MODEL" Seq.Strat.

Pitman (1986), Galloway (1989), Mial (1991), Sloss(1991), Posamentier dan Allen (1993) :

memfokuskan pada modifikasi "model" Sikuen Dasar.

Galloway (1989), Hunt & Tucker (1992) :metoda pengganti penentuan Sikuen dan System tracts.

Plint (1988), Wagoner et al (1990), Nummmeda et aL(1990), Posamentier et al (1992) & Schumm (1993)

” Deskripsi terinci mengenai aspek-aspek spesifik dariSikuen Pengendapan (Depositional Sequence)”.

Sequence stratigraphy,sequences andcomponents there-of werenever defined by theirrelationship to eustatic sealevel (system tracts are anotable exception).

EXXON RESEACHPRODUCTION CO.

Payton 1977 : – ”Seismic Stratigraphy”AAPG Memior 27 : - Regional, chronostratigraphic surface

- Detailed lithologic prediction from seismic data

- Utility of time synchronous surfaces- Genetic units of strata deliniated by

unconformity

Legaretta et.al. 1993

Sediment fluxTectonicsAutocyclic phenomenonClimate

“Accomodation space” conception to eustatic change :Jervey et.al.1988

Wagoner et.al. 1990 : - cores, wirelines and outcrops, High Resolution Strat.Seq.,- marine to continental strata

Significant departures from Flume Experiment : Koss et.al. 1990

Galloway1989 : Wilgus et.al. 1988 :

Early strat.Seq. ModelsSEPM Spec.pub. No. 42

Block diagram Genetic Strat. Seq. :Posamentier & Vail, 1988

Sequence Stratigraphy telah terbukti sebagai alat yangbermanfaat untuk analisa stratigrafi suatu cekungansedimentasi.

Seq.Strat. dapat diterapkan untuk eksplorasi Hidrokarbon denganalasan :

1. Melengkapi alat yg bermanfaat utk analisa pengisian sedimendlm cekungan yg berkaitan dgn : SEA LEVEL CHANGES,TECTONICSME dan SEDIMENT SUPPLY.

2. Seq. Strat. mampu memahami lebih baik rangkaian diantaraPOLA SEDlMENTASI dlm bagian yang berbeda dalam suatucekungan.

3. Seq.Strat. dapat digunakan untuk meramalkan lokasi reservoir,seal – prone interval dan zonazona dalam suatu cekungan.

Alluvial PlainCoastal Plain

Foreshore/Upper ShorefaceShoreface/Shelf

Hypothetical Cross SectionLithostratigraphy and Chronostratigraphy

“A” Sand Nonmarine Member “X”Shale “Z”“B” Sand

•Units are defined by lithology•Rock Units vary in space and time•Boundaries are subjective

Lithostratigraphy

Unconformity and correlative conformityDownlap surface and correlative conformityUnit 1 Unit 2 Unit 3

•Units based on physically observable stratal surfaces•Units vary in space only•Represent natural stratigraphic divisions (“genetically related”)

Chronostratigraphy

Aplikasi SEQEUNCE STRATIGRAPHY utk explorasiHidrokarbon dan produksi ( 3 kategori ) :

1. REGIONAL UNDERSTANDING AND PREDICTION OFHYDROCARBON SYSTEM.

Data :- Regional Well Log- Seismic Geometry

ANALISASEQ.STRAT

MODEL GEOLOGICEKUNGAN

PERAMALAN :- Reservoir- Seals- Source Rocks- Migration System- Trapping Style

ANALISIS SIKUEN STRATIGRAFI

SEISMIKkorelasi batas sekuen, penentuan fasies seismik,

LOGIdentifikasi lingkungan pengendapan

fasies regresi-transgresi :korelasi MFSSequence BoundarySystem Tracks

SB1

SB2

SB3

SB4

SB5

SB6

SB7

SB8

SB9

MFS1

MFS2

MFS3

MFS4

MFS7

MFS6

MFS5

MFS8

SIKUEN 11

SIKUEN 9

SIKUEN 7

SIKUEN 10

SIKUEN 8

SIKUEN 3

SIKUEN 4

SIKUEN 2

SIKUEN 1

SIKUEN

HST1

HST2

HST4

HST3

HST5

TST5

TST3

LST2

TST3

TST2

HST6

TST6

HST8

HST7

TST7

TST8

TST9

TST10

HST9

SIKUEN 5

SIKUEN 6

SB10

MFS9

HST10

TST11

GEOLOGICAL MODEL BASED ONSEISMIC SECTION INLINE 587

Top GUF

Top U TAF

Top L TAF

Top BSM

GUF 11

GUF 12

GUF 13

A B F

U.TAF

Basement

G U F

L.TAF

SE NW

UPPER BAONG

LOWERKEUTAPANG ?

UBSh

MBS 2

Time Depth Curve - Telaga A1

GEOLOGICAL REGIONAL OVER VIEW PETROLEUM SYSTEM

Location

Location

Stratigraphic RegionalColumn

South SumatraSub-Basin

Regional StructureSouth Sumatra Basin

PaleogeographyTalang Akar FormationSouth Sumatra Basin

Oil Maturity MapSub Basin Area

Sub Basin Area

Oil Migration PathwayWithin Talang Akar Formation

Oil Migration PathwayWithin Baturaja Formation

Burial History

PaleogeographyBaturaja Formation

South Sumatra Basin

Location Map“X” Block

Prospect and Lead Map“X” Block

P “X” 1

P “X” 2

L “X” 4L “X” 3L “X” 5

Line Seismic Map“X” Block

PROSPECT AND LEAD LOCATION“X” BLOCK

Location “X” Block

“X” BlockLocation

Play Concept

Aplikasi : 1. FRONTIER Basin.2. Cekungan dengan Data Sumur relatif jarang.

Pendekatan : - Analisa pola penumpukan sedimen berskalabesar pada well-log

- Korelasi regional well-log- Geometri stratal pada seismik regional

Integrasi DATA Bawah Permukaan dg SEISMIK Regional Analisis Kemungkinan kehadirandan sifat Reservoir & Seal secara regional.

Changes in these patterns can be used for sequence stratigraphic interpretation and correlation

Flooding Surface/Sequence Boundary

Maximum FloodingSurface

IncisedValleySequence

Boundary

Highstand is missing,probably eroded away

Lowstand is missing,probably an interfluve

TST

LST

TST

TST

TST

LST/TST

LST

HST

Idealized parasequence stacking patterns of a complete marginal marine depositional sequence

Maximum FloodingSurface

"Transgressive" Surface

Highstand:Progradational

Transgressive:Retrogradational

Lowstand:Aggradational

Highstand:Progradational

Sequence Boundary

Sequence Stratigraphic Analysis of Well Logs:Interpretations of Stacking Patterns

20 120

- 2150m

- 2175m

- 2200m

- 2225m

- 2250m

GR

Aggradational succession –possible composite incised valley fill

Progradational to Retrogradational -shoreface/deltaic deposits

Aggradational to retrogradational succession –valley fill? Channel fill overlain by delta lobes?

SequenceBoundary?

MaximumFlooding Surface Cored

interval*

An example from Southeast Asia

MaximumFlooding Surface?

MaximumFlooding Surface

SequenceBoundary?

Lowstand-Transgressive

Systems Tract?

Lowstand-Transgressive

Systems Tract?

HighstandSystems Tract?

- 2200m

- 2225m

- 2350m

- 2375m

- 2250m

- 2275m

- 2300m

- 2325m

- 2400m

20 120 20 120GRGR

Maximum Flooding Surface

Maximum Flooding Surface

Maximum Flooding Surface

Another Example from Southeast Asia

Cored interval Maximum Flooding Surface?

Maximum Flooding Surface?

MaximumFloodingSurface?

TransgressiveSystems Tract

TransgressiveSystems Tract

HighstandSystems Tract

HighstandSystems Tract

HighstandSystems Tract

Seismic Examples

Seismic Examples of Significant Surfacesand Recognition Criteria

2. UNDERSTANDING & PREDICTING RESEVOIRGEOMETRY, HETEROGENEITIES & SEALS.

Aplikasi Seq.Strat. adalah dalam studi lapangan dan reservoir.

Data :- Well-log rinci- Core- Data Produksi- Penamp. Seismik (3D)

HIGH RESOLUTIONSEQ. STRAT

MODELGEOLOGI

ARSITEKTURRESERVOIR

FloodingSurface

FloodingSurface

Drillingmud injections

Drillingmud injections

UndulatorygeometriesUndulatorygeometries

Horizontalbedding attitudes

Horizontalbedding attitudes

~>30 degreebedding attitude

~>30 degreebedding attitude

~45 degreebedding attitude

~45 degreebedding attitude

~45 degreebedding attitude

~45 degreebedding attitude

CORE DATA

Generic Delta Relationships

Distributary Mouth BarDistributary Mouth Bar

Delta FrontDelta Front

Delta FrontDelta Front

Flooding SurfaceFlooding Surface

3. DEVELOPMENT OF NEW TYPES OF PLAYS BASED ONSEQUENCE STRATIGRAPHY CONCEPT.

Seq. Strat. memfokuskan pads : TIPE SISTEM SEDIMENTASI YANGBARU.

Misal : - Incised fluvial Valleys- Lowstand Coastal Sand Deposite- Submarine Fan.

Aplikasi : > Mature basin : subsurface data banyak> Depositional System khusus daerah distal shelf

environment

Contoh : Mature basin US Gulf Coast US western Interior basin Cretaceous Foreland Basin (Western Canada)

GUIDELINES YANG DIIKUTI :1). Seq.. Strat. terdiri dari Concept & Principles.

2). Seq. Strat. "MODEL" harus dan dapat memodifikasi faktor lokaldalam basin, misal : tektonisme yang mengontrol fasies sedimen danarsitektur stratal.Konsep Sequence harus diaplikasikan dengan cara yang fleksibel (Semuavariabel geologi) Jadi tidak hanya eustacy saja tetapi juga tectonics,sediment supply, depositioal process, dsb harus dipertimbangkan.

3). Objective of Seq. Stratigraphy is definitely not to calibrate a givenStratigraphic interval with the global eustatic sea level chrat.

4). Basic Principles of Seq. Strat. are : TIME an Scale Independent dapat diaplikasikan dengan skala yang luas dari Outcrop and Reservoir toSeismic and Regional basin-fill scale.