9TH JULY, 2014

H. SAIBI

Hydrocarbons, Nuclear, Gas Hydrate

OIL AND GAS

Hydrocarbons

Talk outline

Part 1: Origin – How do oil and gas form?

Part 2: Exploration and Production – How do we find oil and gas and how is it produced?

Origin (1): The Nature of Oil and Gas

Petroleum: Greeks origin (Petro=Rock; oleum=Oil)Called Hydrocarbons because 2 most important

element in both crude oil and natural gas (Carbon + Hydrogen).

Difference between crude oil and gas: size of hydrocarbon molecules: 1-4 carbon atoms: gas (methane: CH4; ethane C2H6; propane

C3H8; butane C4H10) 5 or more carbon atoms: Liquid Crude oil: mixture of more than 100 hydrocarbon molecules

(5-60 carbons in length).

Origin (2): Chemical composition of typical crude oil and natural gas

Crude Oil Natural gasCarbon 84-87% 65-80%Hydrogen 11-14% 1-25%Sulfur 0.06-2% 0-0.2%Nitrogen 0.1-2% 1-15%Oxygen 0.1-2% 0%

Origin (3): Chemistry

Crude Oil

Hydrocarbon

en.wikipedia.org/wiki/Image:Octane_molecule_3D_model.pngen.wikipedia.org/wiki/Image:Petroleum.JPG

• Oil and gas are made of a mixture of different hydrocarbons.

• As the name suggests these are large molecules made up of hydrogen atoms attached to a backbone of carbon.

Origin (4): Plankton

cache.eb.com/eb/image?id=93510

en.wikipedia.org/wiki/Image:Copepod.

en.wikipedia.org/wiki/Image:Ceratium_hirundinella.jpg

• Most oil and gas starts life as microscopic plants and animals that live in the ocean.

Plant plankton Animal plankton

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Origin (5): Blooms

serc.carleton.edu/images/microbelife/topics/red_tide_genera.v3.jpg• Today, most plankton can be found where deep ocean currents rise to the surface

• This upwelling water is rich in nutrients and causes the plankton to bloom

• Blooms of certain plankton called dinoflagellates may give the water a red tinge

© Miriam Godfrey

Dinoflagellate bloom

Origin (6): On the sea bed

upload.wikimedia.org/wikipedia/en/0/04/Plankton.jpg

When the plankton dies it rains down on sea bed to form an organic mush

Sea bed

en.wikipedia.org/wiki/Image:Nerr0328.jpg

If there are any animals on thesea bed these will feed on theorganic particles

Origin (7): Black Shale

upload.wikimedia.org/wikipedia/en/0/04/Plankton.jpg• However, if there is little or no oxygen in the water then animals can’t survive and the organic mush accumulates

• Where sediment contains more than 5% organic matter, it eventually forms a rock known as a Black Shale

© Earth Science World Image Bank

Origin (8): Cooking

www.oilandgasgeology.com/oil_gas_window.jpg

As Black Shale is buried, it is heated.

Kerogen

Gas

Oil

Organic matter is first changed by the increase in temperature into kerogen,which is a solid form of hydrocarbon

Around 90°C, it is changed into a liquid state, which we call oil

Around 150°C, it is changed into a gas

A rock that has produced oil and gas in this way is known as a Source Rock

www.diveco.co.nz/img/gallery/2006/diver_bubbles.jpg

• Hot oil and gas is less dense than the source rock in which it occurs• Oil and gas migrate upwards up through the rock in much the same way that the air bubbles of an underwater diver rise to the surface

• The rising oil and gas eventually gets trapped in pockets in the rock called reservoirs

Rising oil

Origin (9): Migration

Source Rock in subsurface + Reservoir to hold gas/oil

+ Trap on the reservoir rock to concentrate gas/oil into commercial quantities

Origin (10): Ancient Earth

© Ron Blakey, Arizona Flagstaff

• During mid-Mesozoic times around 150 million years ago, conditions were just right to build up huge thicknesses of Black Shale source rocks

Ancient Earth

The world’s main oil deposits all formed in warm shallow seaswhere plankton bloomed but bottom waters were deoxygenated

Origin (11): Source of North Sea Oil

Ancient Earth

© Ian and Tonya West

The Kimmeridge Clay is a Black Shale with up to 50% organic matter. It is the main source rock for the North Sea Oil & Gas

Province

Black Shale

Exploration and Production (1): Oil Traps

• Some rocks are permeable and allow oil and gas to freely pass through them

• Other rocks are impermeable and block the upward passage of oil and gas

• Where oil and gas rises up into a dome (or anticline) capped by impermeable rocks it can’t escape. This is one type of an Oil Trap.

Impermeable

Permeable

Dome Trap

Exploration and Production (3): Reservoir Rocks

Earth Science World Image Bank Image #h5innl

• The permeable strata in an oil trap is known as the Reservoir Rock

• Reservoir rocks have lots of interconnected holes called pores. These absorb the oil and gas like a sponge

This is a highly magnified picture of a sandy reservoir rock (water-filled pores are shown in blue)As oil migrates it fills up the pores(oil-filled pores shown in black)

Exploration and Production (4): Seismic Surveys

Earth Science World Image Bank Image #h5inpjEarth Science World Image Bank Image #h5inor

• Seismic surveys are used to locate likely rock structures underground in which oil and gas might be found• Shock waves are fired into the ground. These bounce off layers of rock and reveal any structural domes that might contain oil

Drill here!

Exploration and Production (5): Drilling the well

• Once an oil or gas prospect has been identified, a hole is drilled to assess the potential

• The cost of drilling is very great. On an offshore rig, it may cost $10,000 for each meter drilled.

• A company incurs vast losses for every “dry hole” drilled

en.wikipedia.org/wiki/Image:Oil_platform.jpg

Preparing to drill requires: • Clearing the land and building

access roads.• Have a source of water nearby, or

drill a water well.• Digging a reserve pit for rock

and mud that comes up in the drilling process.

Exploration and Production (14): At the Refinery

• Before it can be used crude oil must be refined. • Hydrocarbons can be separated using distillation, which produces different fractions (or types) of oil and gas

Oil refinery DistillationPlant

en.wikipedia.org/wiki/Image:Anacortes_Refinery_31911.JPG en.wikipedia.org/wiki/Image:Crude_Oil_Distillation.png

Jet fuel

Car fuel

Road tar

Nuclear Energy

Fuel Pellets

The enriched UF6 is converted into UO2 which is then made into fuel pellets.

The fuel pellets are collected into long tubes. (~12ft).

The fuel rods are collected into bundles (~200 rods per bundle

~175 bundles in the core

Cladding

The material that the fuel rods are made out of is called cladding.

It must be permeable to neutrons and be able to withstand high heats.

Typically cladding is made of stainless steel or zircaloy.

Two common reactor types: Boiling Water Reactor and Pressurized Water Reactor.

BWR: P=1000 psi T=545F

PWR P=2250 psi T=600F

PWR is most common and is basis of marine nuclear power.

World Nuclear Power

Gas hydrates

Methane hydrate lattice

28

Hydrates - What are they?

n Gas Hydrates are solids formed from hydrocarbon gas and liquid water

n They resemble wet snow and can exist at temperatures above the freezing point of water

http://walrus.wr.usgs.gov/globalhydrate/images/browse.jpg

white dot = gas samples recoveredblack dot = hydrate inferred from seismic imagingdotted lines = hydrate-containing permafrost

98% in ocean2% on land

using seismic-reflection profiles

Bottom Simulating Reflection (BSRs)

http://woodshole.er.usgs.gov/project-pages/hydrates/hydrate.htm

dissociating methane hydrate at sediment/water interface