Chapter 11: Energy from the Oceans

• Oil and Gas

• Fisheries

World Geography 3202

What is Oil and Gas??

• oil and gas are the remains of microscopic organisms from millions of years ago.

• The remains of these organisms piled up on the sea floor and and eventually became oil and gas.

How do microscopic Organisms become Oil and Gas??

• organisms die and fall to ocean floor

• the organisms pile up and turn into sedimentary rock.

• over millions of years, these rocks are subject to great pressures, heat and bacterial action.**

• the result of these processes is the formation of oil and gas

The Recipe for oil and gas• four conditions or requirements are necessary:

Source Rock - A shale must contain organic material which is converted to petroleum by burial pressures and temperatures.

Reservoir Rock - A sandstone or other relatively porous rock is required to store and transmit the petroleum.

A Trap - a set of conditions to hold the petroleum in a reservoir and prevent its escape by migration.

Deep enough burial - Temperatures and Pressures are required to "cook" the petroleum out of the organic matter.

Oil Traps:

A. Folding Trap B. Fault Trap

C. Stratigraphic Trap D. Salt Dome Trap

Finding Oil and Gas• In the old day, pre 1900, finding oil was through a method called hit and miss.

• Geologists looked for tar like seeps sitting on the earths surface and “hit” that sight.

• Later searches were concentrated on gently rolling hills and faulted sedimentary structures where wells were drilled and most often missed the oil trap.

• Today we integrate more science and technology into the never ending search for oil.

Finding oil and gas …. With Science and Technology

• we now employ science, technology and a lot of money in the search for oil and gas.

• Ships like this one patrol the sea and tow sound emitting equipment

• the sounds that are produced penetrate the rocks and reflect back to recording instruments on board

• These sounds are recorded by hydrophones and plotted on seismographs to create cross sections in rocks allowing us to find oil deep under the sea/

How we find oil and oil traps...

Survey Ship

• Fault Trap… good chance of oil

Typical Seismograph

1.

2

3

4

DECREASING

DEPTH

After we find an oil source…we drill.

•Wild cat” wells are drilled to test for oil

If they strike oil then they drill wells to determine the size of the reservoirIf they miss oil then they examine core samples for evidence of oil

•Oil quality varies with viscosity

•Heavy, viscous (thick slow running) oil is used for asphalt and electric generating stations

•Light less viscous oil is easier and cheaper to refine. It is used for gasoline, jet fuel, and petroleum products

OIL QUALITY

TAR

Patterns of Offshore Oil Production

• Looking at figure 11.2, on page 184, we can see that most oil regions of the world are on land. 

• The ones that are under the ocean floor are concentrated in the North sea around the United Kingdom and in the Gulf of Mexico

• Figure 11.3 shows the oil production by non - OPEC countries.  It too shows that the North Sea and the Gulf of Mexico are regions of high offshore oil production

• 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 too.

OFFSHORE OIL PRODUCTION AND OIL SPILLS…• The Gulf of Mexico is the world's second largest production area for offshore oil. 

• Natural Phenomenon like Earthquakes, Volcanic Eruptions, Hurricanes and tropical storms

• These natural disturbances can make offshore oil spills in the gulf of Mexico more of a concern

• Consequently the rigs must be well prepared to deal with impending disturbances

•The North sea has two natural disturbances to deal with as well:  The winter storms of the North Atlantic and the threat of icebergs.

OFFSHORE OIL PRODUCTION AND OIL SPILLS

• Planning for these two inevitabilities, storms and icebergs, must be a part of preparation in the North Sea.

Modern Drill Rigs

We will investigate 4 different types of oil rigs used to recover oil from under the ocean floor.

1.Submersible Rigs: With fixed columns grounded on the ocean floor

2. Jack-up Rigs: With extendable legs grounded on the ocean floor

3. Semi-submersible Anchored rigs: Are anchored above the drill site.

4. Semi-submersible Dynamically Positioned: Use thrusters to maintain position above the drill site.

Submersible RigsSubmersible Rigs

•Submersible rigs are normally 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.

Jack-up RigsJack-up Rigs

• Jack-up rigs are able to drill in deeper water than submersible rigs

• are limited to a maximum ocean depth of 100 m

• similar to the submersible in that it rests on the ocean floor

• However its steel legs (Not columns) rest on ocean floor.

Proposed

Semi Submersible -- Anchored RigsSemi Submersible -- Anchored Rigs

• float on the ocean

• limited to a maximum ocean depth of 200 meters.

• rig is towed to the drill site

• Water is pumped in and out of ballast tanks to help stability along with anchor lines

• Oil is stored in pontoons until shipped on-shore.**

Glomar Grand BanksGlomar Grand Banks

This photo was taken off Brazil and shows the importance of maintaining proper balance of stored oil and ballast in the columns

Semi Submersible-Dynamically Positioned

• rigs are able to drill outside the continental shelf.

• they are still limited to a maximum ocean depth of 2000 meters.

• Water is pumped in and out of Ballast tanks to help stability but there are no anchor lines

• dynamic means changing or moving

• Thrusters position the rig over the drill site.

• Like the Anchored rigs oil is stored in pontoons until shipped on-shore**

Oil Rigs and PlatformsOil Rigs and Platforms..

Two Familiar Examples

1. GBS – Gravity Based Structure ( Hibernia)

2. FPSO – Floating Production Storage and Offloading Ship

1. Terra Nova

2. White Rose

Terra Nova Oil Project

• Oil is stored in the FPSO, wells are drilled by a semi-submersible drill rig

Oil production wells are pre-drilled by a semi-submersible drilling platform. The wellheads and production manifolds are placed in glory holes – excavations in the seafloor – that protect the equipment from scouring icebergs.

• A network of more than 40 km of flexible flow-line is used to convey hydrocarbons to and from the wells.

• Produced gases are separated from the oil and re-injected into the reservoir for possible future extraction.

The connection between the FPSO and the subsea flowlines is the spider buoy The spider buoy is the mooring point for the FPSO, and the pathway for oil and fluids that flow to and from the FPSO and reservoir. The spider buoy has a quick-disconnect feature, allowing the FPSO to disconnect and leave the area in an emergency situation like the approach of an iceberg.

Terra Nova FPSO in Bull Arm

FPSO

Tanker

Supply Ship

White Rose Oil Project

HiberniaHibernia

Case Study

Page 187 in text

Drilling Muds• Are a mixture of clay,barium,sulfates and water that is piped down the drill shaft as drilling is taking place

• the mixture cleans the bits and carries rock cuttings back to the surface.

• The mud prevents the caving in of the drill hole

•also reduces blowouts and gushers

and lubricates the drill

Drilling Muds…• drill cuttings are taken back to the surface and treated as they are contaminated with oil from the drill and chemicals in the mud

After they are treated they are released back into the ocean and pile up on the sea floor

Directional Drilling

• allows a number of wells to be drilled from one location

•can increase speed in oil extraction

• allows more oil to be extracted as well.

Physical Factors That Affect Oil Recovery

• Water DepthWater Depth – we cannot drill in areas where the water is too deep for existing technology

• Offshore Meteorological ConditionsOffshore Meteorological Conditions – planners have to be aware of annual temperature ranges, fog, wind, and winter storms.

• Sea IceSea Ice – pack ice and icebergs pose a threat to production and plans are made in the engineering of offshore platforms to deal with these issues

• DistanceDistance

Human Factors and Oil Recovery

• Human ErrorHuman Error – Accidents often result from errors in human judgment

• Errors in DesignErrors in Design – – we all make mistakes. Mistakes have been made from a design perspective on a lot of oil projects. ( Ex: Lifeboat Systems on Hibernia)

• Failure to comply to procedure Failure to comply to procedure – – we often panic in emergency situations; by following protocol, mistakes can be eliminated.

Life on an Oil Rig

Shift Rotation

• Working offshore means you work (most times) 3 weeks out and 3 weeks home

• You have to ride by helicopter to work

• If bad weather sets in…you don’t get home on time

Arriving at work for a 3 week shift

Life on an Oil Rig

Hours of Work

• you work for 12 hours, off for 12 hours

• no days off at sea

• sickness is dealt with right away by staff doctors

Work Roles

• everyone has a specific duty to ensure the “ship” runs smooth

• if you don’t do the work – Your Fired !!

Life on an Oil Rig …

Benefits

• excellent pay• Excellent food and accommodations, although no alcohol or smoking• 3 weeks off – you basically work half a year • lots of training required – helicopter crashes, emergency evacuations

Risks/ Negative Aspects

• loneliness – away from family and friends

• Bad if you have a fear of water or flying

• high risk of injury or death – one of the most dangerous places on earth is on an oil rig

Viability and the Offshore Oil Industry

Viability : Capable of success or continuing effectiveness at something

Factors

• finding new oil fields at a timely rate so that when one reserve runs out, another can fill the void

• increase spending by both private and public sector in research of new technology for the offshore – deep water drilling rigs

• good environmental records – if oil companies produce oil in a environmentally sounds manner and reduce incidents, the governments will likely be more favorable to dealing with them.

Article: The Exxon Valdez, Page 193

1. Read the Article

2. Determine what the human risks/ errors were in this case, what the errors in process where and what could have been done mechanically to reduce the spill in Alaska.