ĐỊA CHẤT DẦU KHÍ ( PETROLEUM GEOLOGY ) - CHƯƠNG 8 pptx

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Chapter 08
Chapter 08
THE
THE
HABITA OF
HABITA OF
HYDROCARBONS IN
HYDROCARBONS IN
SEDIMENTARY BASINS
SEDIMENTARY BASINS
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Introduction
There are approximately 600 sedimentary rock
basins in the world.
A quarter of them are producing petroleum
Before exploitating in a new area, attemting to
locate
drillabe prospects, it is necessery to
establish the
type of basin, what
productive horizons it may
contain and where they may be broadly located
• Even though petroleum reserves can be found in
rocks of all ages, most giant fields and most of
the world's reserves occur in sequences, of Late
Mesozoic and Cenozoic age ( Figure ) .
Paleozoic rocks probably had potential to
generate hydrocarbons equal to that of these

younger rocks, but there has been more time in
which to destroy all or part of the petroleum
through uplift and erosion (Halbouty et al,
1970).
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• Worldwide reserves can be related to their location within a
petroleum basin, regardless of its basin type (Figure )
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8.1-The Sedimentary Basin Concept
•
A general term for any large area of tectonic origin
with a thick accumulation of sedimentary rocks.
•
A basin is a geological structure with a unique
sequence of rocks that are dissimilar to those outside
the basin.
• A low area with no exterior drainage.
• Include both depression itself and the thicker-than-
everage sediments that fill it
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Idealized pattern of a sedimentary basin
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Sedimentation patterns over arch, shelf and basin
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Main content:
• Geometry of Sedimentary Basins
• Sediment Fill
• Tectonic Processes and Timing
• Basin-Forming Mechanisms
• Sedimentary Basin Classification
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Geometry of Sedimentary Basins
Geometry of Sedimentary Basins
It is tempting to believe that a sedimentary basin
was deepest where its sediments are thickest,
but this is not necessarily true
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Non-coincidence of depocenters, topographic low and point of maximum basement
subsidence in a land-derived, prograding clastic wedge
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Sediment Fill
Sediment Fill
Basins can be characterized by the sediments that fill
them.
They can be dominated by continental, shallow
marine, or deep marine sediments, depending on
their elevation and the interplay between the rate of
subsidence and the rate of sedimentation

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Tectonic Processes and Timing
Tectonic Processes and Timing
• An important aspect of sedimentary basins is the
nature and timing of tectonic processes.
• The types of folds and faults that develop within a
basin are partly due to deformation mechanisms and
partly to its sediments
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Basin
Basin
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Forming Mechanisms
Forming Mechanisms
• Basins form as a result of large-scale vertical and
horizontal movements within the earth's upper
layers, which can be explained through the
widely accepted theory of plate tectonics.
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• The earth's outermost shell is a rigid layer
called the lithosphere, which consists of crust
and uppermost mantle. Topographic lows form
on the earth's surface where the crust is thin,
and composed of dense basaltic rocks
• The rigid lithosphere overlies a less viscous
layer called the asthenosphere

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The earth's outermost layers
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Distribution of lithospheric plates, showing relative velocity and
direction of plate separation and convergence in centimeters per
year
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Initiation of rifting and ocean floor spreading over
Initiation of rifting and ocean floor spreading over
continental crus
continental crus
Pre-rift domal bulge
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Innitial radial rift
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Early separation stage
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MODEL OF A DIVERGING PLATE BOUNDARY
MODEL OF A DIVERGING PLATE BOUNDARY
The separated continents are now far apart, and basins develop along their passive
margins
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MODEL OF SUBDUCTING PLATE MARGIN
MODEL OF SUBDUCTING PLATE MARGIN
At a subduction zone, the leading edge of one plate overrides another, and the
overridden plate is dragged down into the mantle and consumed
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MODEL OF A COLLISIONAL PLATE MARGIN, SHOWING COLLISION
MODEL OF A COLLISIONAL PLATE MARGIN, SHOWING COLLISION
BETWEEN OCEAN PLATE AND A CONTINENTAL MARGIN
BETWEEN OCEAN PLATE AND A CONTINENTAL MARGIN
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MODEL OF A COLLISIONAL PLATE MARGIN,
MODEL OF A COLLISIONAL PLATE MARGIN,
SHOWING CONTINENT
SHOWING CONTINENT
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CONTINENT COLLISION
CONTINENT COLLISION