Systems Model and Offshore Oil
Offshore Oil: Decision to Recover
• The determination must be made
whether cost of inputs and
processing will be offset by the
value of the output oil.
There are several factors that affect the profitability
of oil production.
Production can not proceed unless the company
has a good expectation of making a profit.
Oil Price – Cost of Production = Profit
Physical Factors Affecting Recovery
• Ocean related factors include;
 Ocean Depth , Ocean currents, Icebergs & Pack
ice
• Climate/weather related factors include;
 Wind speeds, Storms, Waves
• Oil Related factors include;
 Size of the reserve, Oil quality
• Environmental protection factors;
 Other resources like fish stocks, marine
mammals, and spawning grounds would be
affected in the event of an oil spill.
Human Factors Affecting Recovery
Worker Safety
• How safe can the drill rig and production platform be
for the workers?
Financial Factors include:
• cost of inputs - building a rig to withstand icebergs,
hurricane winds, or to drill at great depths.
• cost of processes – extracting the oil, transporting the
oil from off-shore to land, or maintaining equipment.
• price of oil which is set, but can change and then you
determine if enough money is recovered from the oil to
exceed the cost of production.
Offshore Oil: Decision to Recover
The main determinate is…
… whether the cost of overcoming all other factors
will be offset by the price oil can be sold for and
make the venture financially viable!
A Brief History of Oil Recovery
Keeping the Connection to Land
~ In the 1860’s wharves were built extending
365m out into the ocean to facilitate ocean drilling
off California.
A Brief History of Oil Recovery
Letting go of Shore
~ In the 1920’s a drill rig was built on wooden
pilings in lake Maracaibo, Venezuela.
A Brief History of Oil Recovery
Moving to Steel
~ In the 1930’s a drill rig was built on steel
structures in the Gulf of Mexico but it was limited to
7m of water or less.
A Brief History of Oil Recovery
Letting go of the
Ocean Floor
• In 1956, the first drill
ship was built allowing
drilling in deeper
water.
• These types of drill
ships allowed
exploration off the
shores of
Newfoundland.
Drill Ships
Off-shore Oil Rigs
Modern Drill Rigs
(Pg. 186 - Figure 11.4)
A. Submersible
Rigs
B. Jack-up Rigs
C. Semisubmersible
Anchored
rigs
D. Semisubmersible
Dynamically
Positioned
Submersible Rigs
Fixed columns ground them on the ocean floor!
 Usually limited to ocean
depths of 20 m. For this
reason they are limited to
continental shelves,
relatively close to shore.
 The rigs are floated as
they are towed to drill site.
Once in position ballast
tanks are flooded until
columns rest on ocean
floor.
Submersible Rigs
Jack-Up Rigs
• Extendable legs ground them on the ocean floor.
 Are limited to a maximum
ocean depth of 100 m.
 The jack-up is similar to
the submersible in that it
rests on the ocean floor.
However its steel legs (Not
columns) rest on ocean
floor.
Jack-Up Rigs
Semi-Submersible Anchored Rigs
 Limited to a max. ocean depth
of 200 m.
Built on land, then flooded and
towed to the drill site.
Water is pumped in and out of
ballast tanks to keep stability
along with anchor lines.
Oil is stored in pontoons until
shipped on-shore.
• Float BUT are
anchored above
the drill site.
Semi-Submersible Anchored Rigs
Semi-submersible Dynamically Positioned
• Able to drill outside the
continental shelf. Still limited to a
max. ocean depth of 2000 m.
• Like other rigs they are towed to
the drill site.
• Water is pumped in and out of
ballast tanks to help stability
(NO anchor lines).
•
Like the Anchored rigs oil is
stored in pontoons until
shipped on-shore.
•
Note: dynamic means
changing or moving.
Use thrusters to keep
position above the
drill site.
Semi-submersible Dynamically Positioned
thrusters
Semi-submersible Dynamically Positioned
Eirik Raude - The World’s
largest self-propelled, semisubmersible, all weather oil
drilling rig.
Hibernia Case Study
• Pg. 187-191
Directional Drilling
Figure 11.5 on page 187 of your text. This technique:
A. increases the drill holes exposure to source (porous) rock.
B. allows drill companies to reduce movement from one small
oil pocket to the next.