Sedimentary Basin Formation PDF

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Summary

Sedimentary basin formation Wiekert Visser Main questions in hydrocarbon exploration ¾ Basin Shape: Area and thickness of sedimentary fill • Satellite image, gravity/magnetics, seismic mapping ¾ Tectonic setting: what type of traps to expect • Plate tectonics, gravity/magnetics, satellite image ¾ Hy...

Description

Sedimentary basin formation

Wiekert Visser

Main questions in hydrocarbon exploration Ü Basin Shape: Area and thickness of sedimentary fill • Satellite image, gravity/magnetics, seismic mapping

Ü Tectonic setting: what type of traps to expect

• Plate tectonics, gravity/magnetics, satellite image

Ü Hydrocarbon Charge: oil or gas?

• Wells,seismic facies mapping, satellite image (seeps), plate tectonics, paleoclimate, modelling,

Ü Reservoir/seal: reservoir quality, seal risk

Impact Seismic stratigraphy

• Seismic facies & depositional sequence mapping, wells, plate tectonics, paleogeography, paleoclimate

Ü Trapping style & size

• Detailed seismic mapping, satellite, arial photography, models The main questions in an early exploration phase relate to the basin formation processes. Seismic stratigraphy is a valuable tool in answereing some of these questions

Basin evolution Primary controls on basin evolution: 1. Type of substratum (continental, oceanic, transitional) 2. Proximity to plate boundary 3. Type of nearest plate boundary (active, passive, transform, collision) 4. Geodynamic processes during basin evolution (rifting, stretching, flexure, compression, extension, translation) Unravelling the basin fill to predict/understand the distribution of reservoirs, seals, and source rocks, requires understanding of basin fomation processes

Break-up of continents

After H.H. Hess, 1962

Passive Margin development

Plate tectonics: the Wilson cycle G: Peneplaned Mountain

400 MA

F: Collision Orogeny

A: Stable Craton E: Closing Remnant Ocean Basin

0 MA

B: Early Rifting D: Subduction Zone

200 MA After T.Z. Wilson, 1970

C: Full Ocean Basin

Ocean-Continent collision

Plate tectonics: the Wilson cycle G: Peneplaned Mountain

400 MA

F: Collision Orogeny

A: Stable Craton E: Closing Remnant Ocean Basin

0 MA

B: Early Rifting D: Subduction Zone

200 MA After T.Z. Wilson, 1970

C: Full Ocean Basin

Continent-Continent collision

Basin type and plate tectonic setting GROU P FORELAN D

FORE-ARC

WREN CH

RI FT /SAG PASSI V E M ARGI N

Courtesy:

EX AM PLE

SU BSI DEN CE M ECH AN I SM

PLAT E T ECT ON I C EN V I RON M EN T

M ECH AN - T H ERM AL CRAT ON I C I CAL

5

C-C

5

5 5 5

5 5

O-C

O-O

5

5

5

5

5

5

5

5

5

5

5

5

5

Distribution of basin types

FORE-ARC FORELAN D PASSI V E M ARGI N RI FT /SAG WREN CH Courtesy:

Rift induced Intra-cratonic basin

Olmedo: Seismic crossection & interpretation

Seconds TWT

0 1 2 3 4

10 km

DS. III Post-rift Tertiary

DS. I Pre-rift Paleozoic Courtesy Shell

Palinspastic reconstruction of Cratonic rift basin

Palinspastic reconstruction of Cratonic rift basin

The Olmedo basin is a rift/sag basin, which developed in a pure continental domain. Most critical in the exploration play is the mapping the extent of the lacustrine facies (high amplitude. High continuity), which developed in the deeper part of the basin. This sequence may contain source rocks. Courtesy Shell

North Sea, failed rift basin Troll gas field

The North sea is a failed rift basin: the rifting did not result in the opening of a new ocean. The basin developed as an intra-cratonic rift basin. This rift/sag basin had extensive marine influence. Seismic stratigraphic mapping in this basin has been critical in understanding the development of turbidite systems.

R Courtesy Shell

Passive margin example, West Africa

Courtesy Shell

Suriname: play types S

Onshore blocks

Tambaredjo Oil Field

offshore blocks

Turbidite Play

N

Shelf-edge canyon Play

stratigraphic plays Carbonate Mid Miocene Base Tertiary

LOWER CRETACEOUS LOWER CRETACEOUS MARINE SOURCE ROCK MARINE SOURCE ROCK

CONJECTURED LOWER CONJECTURED LOWER JURASSIC LACUSTRINE JURASSIC SOURCELACUSTRINE ROCK SOURCE ROCK

CANJE FORMATION CANJE FORMATION SOURCE ROCK SOURCE ROCK

Structural traps

Salt Presence predicted based on Takutu graben data Hydrocarbon migration path

Understanding the passive margin basin development processed allowed to predict that the synrift depositional sequence was missing from existing geological models. Seismic stratigraphy in this basin is most relevant for sand/shale distribution prediction and shelf-edge & turbidite mapping.

R

South China sea area

NE Borneo active margin R Red t faul iver

Luconia Carbonate province

Baram delta area

Stable shelf Courtesy Shell

Active margin

Cross section Baram delta

Carefull mapping of topsets, foreset, and bottomsets has resulted in a good understanding of reservoir distributionin this area.

Courtesy Shell

Bram delta seismic cross section SE

NW

5 km -

10 km

Courtesy Shell

R

Foreland basin: Adriatic Sea

After: M. Pieri, 1983)

Po basin (Italy)

5 km

Courtesy Shell

Bacterial gas fields in turbidites (Adriatic basin)

• Bacterial gas found in turbiditic sands • Best reservoirs found off-structure • Turbidites onlap against syn-sedimentary growing structures • Turbidites flow direction affected by compressional folds

Transport direction of sediments affected by syndepositional folding

Turbidites onlapping growing structure

R

South China sea area

NE Borneo active margin R Red t faul iver

Luconia Carbonate province

Thailand satellite image during flood

Main strike-slip faults

Sirikit oilfield

Cross section Phitsanulok basin

In this lacustrine basin, the seismic facies mapping of the source rock depositional sequence contributes to the exploration of the basin. Courtesy Shell

Phitsanoluk basin, source rock facies

Lacustrine, source rock-prone facies (high continuity). Note poor display, no amplitude variation information Courtesy Shell

Seismic sections Sirikit field...