Transcript Offshore Oil Formation

Offshore Oil Formation
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The formation of oil takes a tremendously
long time. Millions of years ago plants and
animals of the oceans died & settled on the
ocean floor. While large organisms
contributed to the oil it was often the mass
of small and microscopic organisms that
contributed the bulk of the carbon for OIL.
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Over many thousands of years bacterial
action and extreme pressure from layers of
sediment converted the organic matter to oil
& gas. The extreme pressure came form the
continuous build up of sediment. The
pressure created tremendous amounts of
heat which helped the process along.
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The oil moved within the soil and oil reserves
formed when non-porous rock lay above
porous rock. Oil seeps up through the porous
rock & is trapped by the non-porous rock.
Sedimentary Basins of Canada
1. Western Canada Sedimentary Basin
(our primary source of oil)
2. Hudson Bay Basin
3. Mackenzie and Banks Basins
4. Canadian Arctic Basin
5. Baffin Bay
6. Labrador Sea Shelves
7. Scotian Shelf
8. Grand Banks
9. Anticosti
10. Maritimes Basins.
Atlantic
Sedimentary Basins
Hibernia Cross Section
Oil (light-green lines
and blobs) and
gas (red lines)
in the Hibernia
Formation (yellow)
in the Carson Basin,
mainly in stratigraphic
traps. The brick colour
underlying the oil and
gas stream lines
represents the Egret
type
source rock.
Oil and Gas Traps
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1.
2.
All oil and gas traps have
a nonporous rock cap and
a porous rock source.
The porous rock allows the oil to seep into
the cavity and the nonporous rock prevents
the oil from leaving.
Oil Reserves
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Fold Trap: the up fold or anticline in the layers of the
earth's crust form the reservoir.
Oil Reserves
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Fault Trap: the
vertical
movement of the
earth's crust
forms a vshaped
reservoir.
Oil Reserves
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Salt Dome Trap:
The salt dome
forms an up-fold
in the earth's
crust not unlike
the anticline
caused by
tectonic forces.
Oil Reserves
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Stratigraphic trap:
has a former
limestone reef as
its porous rock
feeding the
reservoir.
Submersible Oil Rig
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Supported primarily on large pontoon-like structures
submerged below the surface. The operating decks
are elevated 100 or more feet [30 m] above the
pontoons on large steel columns.
Once on the desired location, this type of structure
is slowly flooded until it rests on the seafloor. After
the well is completed, the water is pumped out of
the buoyancy tanks, the vessel refloated and towed
to the next location.
Submersible rigs are normally limited to ocean
depths of 20 m.
Semi Submersible
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Float on the ocean
This floating drilling unit has pontoons and
columns that, when flooded with seawater,
cause the pontoons to submerge to a
predetermined depth. Although it is moved by
wave action, it sits low with a large part of its
structure under water. This, combined with
eight huge mooring anchors, make it a very
stable installation
200 m for anchored and 2000 m for
dynamically positioned
Ocean Ranger (semi submersible)
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Valentine's Day, 1982: a terrible storm rages off the
coast of Newfoundland. On the Grand Banks, the
Ocean Ranger, the world's mightiest drilling rig, is
pounded by waves more than 20 metres high. At the
height of the storm, the "indestructible" rig begins to
tip over, then capsizes. All 84 men on board — 56 of
them from Newfoundland — perish.
http://archives.cbc.ca/environment/extreme_weather
/topics/349/
http://archives.cbc.ca/environment/extreme_weather
/topics/349-1874/
http://www.thecanadianencyclopedia.com/index.cfm
?PgNm=TCE&Params=A1ARTA0005876
Jack-up Oil Rig
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Instead of floating over
its drilling location the
Jackup has long leg
structures, which it
lowers to and into the
sea bed raising the rig
out of the water. (100
m)
Gravity Based Oil Rigs
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The Hibernia GBS sits on the ocean floor
approximately 200 metres in depth with its
topsides extending approximately 50 metres
out of the water. The platform acts as a small
concrete island with serrated outer edges
designed to counter ice bergs.
http://www.hibernia.ca
http://www.thecanadianencyclopedia.com/index.
cfm?PgNm=TCE&Params=M1ARTM0011173
FPSO
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A Floating
Production,
Storage and
Offloading
Vessel
Once the field is depleted, the FPSO can be
moved to a new location.
In areas of the world subject to cyclones
(NW Australia) or icebergs (Canada),
some FPSOs are able to release their
mooring/riser turret and
steam away to safety in an emergency.