PART FIVE

Off-shore Oil Formation and Reserves

How Oil Is Formed• Millions of years

ago plants and animals of the oceans died & settled on the ocean floor.

Sediments covered the dead organisms

Oil reserves form when non-porous rock lies above

porous rock underneath.

Oil seeps up through the porous rock & is trapped by the non-porous rock.

Extreme pressure and heat and bacterial action converts the organic matter into oil & gas.

Oil Reserves Pg. 183

• Fold Trap: the up fold or anticline in the layers of the earth's crust form the reservoir.

Oil Reserves• Fault Trap: the vertical movement of the earth's

crust forms a pyramid or v-shaped reservoir.

Oil Reserves

• 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• Stratigraphic trap: has a former limestone reef

as its porous rock feeding the reservoir.

Techniques Used to Locate Reserves

Before 1900’s• The search for oil was limited. Had to look along

fault lines for oil seeping to the surface (EX: Jed & Granny Clampett and the “Beverly Hillbillies”).

After early 1900’s• Geologists knew to drill in gentle anticlines or

faulted sedimentary rock where reservoirs of oil might occur. (Not always successful).

• “Hit and miss” operations….

Techniques Used to Locate Reserves

• ships tow sound emitters & hydrophones to send sound towards earth’s crust.

• different rock layers reflect sound differently.

• computers convert the sound data into 3D pictures of the ocean’s rock layers.

Modern oil exploration on the seas

Techniques Used to Locate Reserves

“Wild cat” wells are drilled to test for oil: – if they strike oil then delineating wells are drilled to

determine the size of the reservoir. – If they miss oil then the core samples are examined

for evidence of oil.

Steps/stages in Oil Exploration: What is the SEQUENCE?????

• Recording sound waves using hydrophones

• Drilling wildcat wells, OIL or NO oil???

• Analyzing the seismic data

• If drilling produces a dry hole, core samples taken

• Directing sounds waves to ocean floor

• Additional wells used to determine size of reserve

Steps/stages in Oil Exploration: The SEQUENCE is…….

• Directing sounds waves to ocean floor

• Recording sound waves using hydrophones

• Analyzing the seismic data

• Drilling wildcat wells, OIL or NO oil???

• Additional wells used to determine size of reserve

• If drilling produces a dry hole, core samples taken

Patterns of Offshore Oil ProductionFIGURE 11.2 PG. 184

Patterns of Offshore Oil Production

FIGURE 11.2 PG. 184

• Most oil regions of the world are on land.

• Oil regions under the ocean floor are concentrated in the North sea around the UK and in the Gulf of Mexico.

Gulf of Mexico North Sea West Africa

(Ivory Coast)

Patterns of Offshore Oil Production

• FIGURE 11.3 PG. 185

• It also reveals that OFFSHORE oil production is increasing faster than land production of oil.

• West Africa, especially around the Ivory Coast,

seems to have high oil reserves and is increasing in oil production.

Where are most of the world’s proven oil reserves located?

PART SIX

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.

Physical Factors Affecting Recovery

• Ocean related factors include; Ocean Depth , Ocean currents, Icebergs & pack

ice

• Climate/weather related factors include; Wind speeds, Storms, Monsoons, Hurricanes

• 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 - transporting the oil from off-shore

to land, or maintaining equipment.• price of oil which is set 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 RecoveryLetting 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 RigsModern Drill Rigs (Pg. 186 - Figure 11.4)

A. Submersible Rigs

B. Jack-up RigsC. Semi-

submersible Anchored rigs

D. Semi-submersible 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 http://www.youtube.com/watch?v=zLLqXaWL1Vk&feature=related

Semi-Submersible Anchored Rigs

• Float BUT are anchored above the drill site.

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.

Semi-Submersible Anchored Rigs

Semi-submersible Dynamically Positioned

Use thrusters to keep position above the drill site.

• 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.

Semi-submersible Dynamically Positioned

thrusters

Semi-submersible Dynamically Positioned

Eirik Raude - The World’s largest self-propelled, semi-submersible, all weather oil drilling rig. 

Gravity Based Structure - GBS

• Submersible - sits on ocean floor.

• Made of 4 ft thick concrete walls.

• Teeth to break apart ice and icebergs

• 80 m of ocean water

• Hibernia…the world’s first of this type.

• The largest in the world!

Directional drilling

• Newest technology!!!

• Flexible shaft used to drill in different directions.

• Don’t have to relocate a drill rig when a deposit dries up.

• Saves a LOT of money & time

• Offshore Work (6 min 7 sec)• Jack-up Oil Rig (14 sec)

• Jack-up rig towage (23 sec)• Deepwater Offshore Drilling Rigs.(2 min 38 sec)

• Geology formation basin trap oil (34 sec)• Norwegian Oil Rigs .(1 min 52 sec)

• Offshore Drilling Fight - CBS News .(3 min 05 sec)• Jack-up Rig Launch .(3 min 21 sec)

• Oil Drill Animation (42 sec)• A look at Life on an offshore Oil Rig .(5 min 24 sec)

Hibernia Case Study

• Pg. 187-191