Topics: Structural Geology in Petroleum...

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Structural Geology in Petroleum Exploration Topics: Petroleum System Traps Exploration Methods (seismic) Maui Field Example Salt Tectonics Reading: 1. Outline in website 2. Pdf file: Geology for Petroleum Exploration, Drilling, and Production by Norman J. Hyne, 1984, pages 173-197. 3. Salt Structures- Ch. 19 of Fossen Factors required to make a conventional Oil Deposit A Sedimentary Basin with: Source rock- rich in organic matter Burial heating maturation Reservoir rock- porous and permeable Trap- structural trap stratigraphic trap Petroleum system Oil Exploration Strategy: Find the Traps The most common traps are structures Can’t see the oil ahead of the drill So exploration often targets the structures in hopes of finding oil Origin of Petroleum Oil forms from the decay and transformation of dead organisms (algae) buried in sedimentary rocks % Total Organic Content

Transcript of Topics: Structural Geology in Petroleum...

Page 1: Topics: Structural Geology in Petroleum Explorationpages.geo.wvu.edu/~jtoro/structure/ppt/18Structures_Petroleum.pdf · Structural Geology in Petroleum Exploration ... Gullfaks Field

Structural Geology in Petroleum Exploration

Topics: Petroleum System Traps Exploration Methods (seismic) Maui Field Example Salt Tectonics

Reading: 1. Outline in website2. Pdf file: Geology for Petroleum Exploration, Drilling, and

Production by Norman J. Hyne, 1984, pages 173-197. 3. Salt Structures- Ch. 19 of Fossen

Factors required to make a conventional Oil Deposit

• A Sedimentary Basin with:• Source rock- rich in organic matter

• Burial heating maturation

• Reservoir rock- porous and permeable

• Trap-– structural trap

– stratigraphic trap

Petroleum system

Oil Exploration Strategy:

Find the Traps

The most common traps are structures

Can’t see the oil ahead of the drill

So exploration often targets the structures in hopes of finding oil

Origin of Petroleum Oil forms from the decay and

transformation of dead organisms (algae) buried in sedimentary rocks

% Total Organic Content

Page 2: Topics: Structural Geology in Petroleum Explorationpages.geo.wvu.edu/~jtoro/structure/ppt/18Structures_Petroleum.pdf · Structural Geology in Petroleum Exploration ... Gullfaks Field

Source Rocks

Black organic-rich marine shales

Organic matter is preserved in low-oxygen water

Restricted marine basins and zones were water rises from the deep

Maturation of Organic MatterAt about 60o C transformation of kerogen begins

• Liquid hydrocarbons begin to form

Above 140o C only gas is produced

Migration of oil Oil is less dense than water

Oil will move up by buoyancy

Oil needs a permeable bed to move

It will stop when it reaches an impermeable bed

Migration

Eastern Venezuela

Western Canada

Oil Reservoirs Permeable reservoir bed

Impermeable seal

Porosity

Open space!

Sandstone

Page 3: Topics: Structural Geology in Petroleum Explorationpages.geo.wvu.edu/~jtoro/structure/ppt/18Structures_Petroleum.pdf · Structural Geology in Petroleum Exploration ... Gullfaks Field

Trap Types Stratigraphic Traps

Structural Traps

3D Structural Closure, Cooper Basin (Australia)

Merrimelia Fm: - Starts the Cooper Basin - Waxing and waning of glacial sediments

Cooper Basin

Tria

ssic

Triassic Inerval

Per

mia

n

Toolachee Fm

Roseneath Shale

Epsilon FmMurteree Fm

Patchawarra

Tirrawarra Fm

Car

boni

fero

us

Merrimelia Fm

Trap Terminology Fault Traps

Page 4: Topics: Structural Geology in Petroleum Explorationpages.geo.wvu.edu/~jtoro/structure/ppt/18Structures_Petroleum.pdf · Structural Geology in Petroleum Exploration ... Gullfaks Field

Gullfaks Field North SeaGullfaks Field North Sea Gullfaks Field North Sea

Fossen, 2010

Map of the Murre Field

Newfoundland

Compressional Traps

Traps in Strike-Slip settings

Positive Flower Structures

Page 5: Topics: Structural Geology in Petroleum Explorationpages.geo.wvu.edu/~jtoro/structure/ppt/18Structures_Petroleum.pdf · Structural Geology in Petroleum Exploration ... Gullfaks Field

How to see in the subsurface?

Drilling

Structural Interpretation

Seismic Reflection Imaging

• Send sound into the rock, and collect the echoes

Seismic Acquisition

Seismic shotgather-

Every vertical squiggle is from one geophone

3D Seismic Image

Salt

Page 6: Topics: Structural Geology in Petroleum Explorationpages.geo.wvu.edu/~jtoro/structure/ppt/18Structures_Petroleum.pdf · Structural Geology in Petroleum Exploration ... Gullfaks Field

3D Geological Model

Offshore PlatformMaui Field, New Zealand

Major Hydrocarbon Provinces in North America

Sedimentary Basins

Page 7: Topics: Structural Geology in Petroleum Explorationpages.geo.wvu.edu/~jtoro/structure/ppt/18Structures_Petroleum.pdf · Structural Geology in Petroleum Exploration ... Gullfaks Field

Gulf of Mexico

Gulf of MexicoSalt

Salt moves driven by buoyancy

•Salt density= 2 g/ cm3

•Salt undergoes no compaction

•Shale Density is initially 40% water

•Initial Density = 1.8 g/ cm3

•Water expelled during compaction

• Final Density = 2.4 g/ cm3

Gypsum, Ca(SO4).2H20

Halite, NaCl

Salt Traps

Sequential Stages of a Salt Diapir

Page 8: Topics: Structural Geology in Petroleum Explorationpages.geo.wvu.edu/~jtoro/structure/ppt/18Structures_Petroleum.pdf · Structural Geology in Petroleum Exploration ... Gullfaks Field

Seismic Image of a Salt Dome Rootless Salt- Gulf of Mexico

AAPG Explorer, 2013

3D Seismic Interpretation of Salt Structures

Sandbox Experiment

Relationship between diapirism and normal faulting

Relationship between Salt Movement and Sedimentation

Initial syncline are now anticlines

Syncline

Extension Above Salt Diapir

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Salt Domes Pierce the StrataFractures around Salt Domes

Ant-Tracking displaying radial fracture pattern around salt domes

8km

Salt Structures vs. Tectonic Structures

•Caused by movement of salt, not by plate boundary stresses

•Often linked to sedimentation

•Often localized by tectonic structures

•Both upwards movement of salt and salt withdrawal cause deformation