SEMINAR

TOPIC: GAS HYDRATES

GUIDED & COORDINATED BY: SUBMITTED BY:MR. SAIF V KHASIM AJMAL ROSHAN.PASST. PROFESSOR ME 1 , 13MECHANICAL DEPT MECHANICAL DEPT

IMPORTANCE OF ENERGYEnergy is fundamental to the quality of our lives.

Nowadays, we are totally dependent on an abundant and uninterrupted supply of energy for living and working.

It is a key ingredient in all sectors of modern economies.

DIFFERENT PHASES OF PETROLEUM• COAL• OIL• SHALE GAS• OIL SHALE• OIL SANDS• METHANE HYDRATES

PETROLEUM DESCRIBES ORGANICALLY FORMED C-H CHAINS - RELEASES ENERGY WHEN IT REACTS WITH OXYGEN THROUGH BURNING

Coal and gas

swampy land environment…

Burial of Plants Decomposition without oxygen Coal mining along in-situ coal seams & Gas expelled

Oil and gas

• Burial of plankton Maturation with heat and pressure Migration of oil/gas Trapping in reservoir

• This depends on; 1. Plankton type 2. Burial/Maturation extent

• Plankton are microscopic organisms that live in watery environments.

• If the buried Plankton is lignin rich (material present in plant cell walls) then it matures directly to Gas

• Otherwise it is probably lipid rich and will mature initially to form Oil

What if… there is no migration ? OPTION 1: petroleum is ‘trapped’ in the source

rock due to low permeability leading to… Fracking to release Shale Gas

• OPTION 2: the source rock has not been buried/heated

enough for migration of the petroleum leading to… Heating to release Oil Shale

• What if… the oil has migrated BUT bacteria exists in the reservoir?

Bacteria in reservoirs live off (eat) the light ‘short-chained’ hydrocarbons leaving only heavy oil which is described as Oil Sands/Tar Sands.

• Bacteria is more likely to exist in shallower and cooler reservoirs that are oxygenated e.g. by contact with surface waters

OUTLINE OF PRESENTATION

1. WHAT ARE GAS HYDRATES?2. OCCURRENCE OF GAS HYDRATES3. ARE GAS HYDRATES SUSCEPTIBLE TO

CLIMATE CHANGES?4. GAS HYDRATE PRODUCTION METHOD

A fuel to ignite worlds energy crisis it looks like ice – but put a flame to it and it goes

blaze

WHAT ARE GAS HYDRATES

• Crystalline Solids composed of H₂O and gas; the gas molecules (guests); are trapped in water cavities (host) that are composed of hydrogen- bonded water molecules. Typical natural gas molecules include methane, ethane, propane and CO₂

- One volume of methane hydrate typically contains about 160 volumes of methane gas

• occur abundantly in nature Around 6.4 trillion (6.4×1012) tonnes of methane is trapped in deposits of methane

clathrate on the deep ocean floor.

• Are stable at low temperature and high pressure

• TYPES OF GAS HYDRATES:-• Hydrates are basically of three types, Type I, Type II & Type H. Each has different

No. of water and gas molecules.• The ratio of water molecules to gas molecules is called hydrate number.• The amount of gas actually contained is called the "Degree of Filling".

• TYPE I:-o § It is usually smaller molecules.o § Type I hydrate formers include 1) Methane 2) Ethane 3) Carbon dioxide

• TYPE II:-o § It is usually larger molecules.o § Type II hydrate formers include 1) Propane 2) Isobutane 3) Nitrogen

• TYPE H :-o § Type H hydrates are formed by larger molecules but only in the presence of a smaller

molecules, such as methane.o § Type H hydrate formers include 1) 2-Methyl butane 2) Methyl cyclo pentane

CONDITION OF FORMATION:-

Hydrates are formed when -• A sufficient amount of water is present• Gas hydrates exists where the water depths

exceed 300 to 500 meters.• The right combination of temp. & Pressure.• The hydrate former gases are present.

Where and How Does Gas Hydrate Form?

Gas hydrate is stable in the underlying sediments to a depth of about 225 m below the seafloor. Also gas hydrate is stable from about 200 to 600 m within the permafrost and from 600 m to ~1100 m beneath the permafrost.

Global Occurrence & Distribution of Natural Gas Hydrates

This what happens!!!

PRODUCTION

• DEPRESSURIZATION• THERMAL STIMULATION• CO₂ REPLACEMENT OR INHIBITOR

INJECTION

DEPRESSURIZATION

•MOST PRACTICAL AND COST EFFECTIVE METHOD•WELLBORE PRODUCTION LEAD TO FLUID FLOW & PRESSURE•HYDRATES DESTABILIZES AND GENERATED GAS FLOW TO WELL•GAS CAN BE COLLECTED

THERMAL STIMULATION

• Main objective is to temperature within the reservoir

• Destabilizes the gas hydrate• Thermal heating alone is inefficient and expensive

means of producing gas hydrates for long term • Limitation- 75% heat applied will be wasted by non

hydrate strata (thief zone).• - horizon should be having high porosity This limitation make it expensive

By solar energy

CO₂ REPLACEMENT/INHIBITOR INJECTION

• The ability of CO₂ molecule to displace methane molecule in the hydrate cage.

• Without the hydrate cage being broken or melted.

• Certain chemicals and alcohols have capability to shift the pressure and temperature needed for hydrates.

• Shift hydrate equilibria and lower the hydrate formation temp. Eg: methanol, MEG, DEG.

• Enable hydrate dissociation and methane release.

Climate change• Methane from hydrate reservoir might significantly modify

the global green house, because methane is ~20 times as effective as CO₂.

• More methane exists in the present day atmosphere.

• Because hydrate breakdown, causing release of methane to the atmosphere, can be related to pressure caused by glacial sea level fluctuation.

• Gas hydrate may play a role inn controlling long term global climate change.

CONCLUSION• Pure methane hydrate produces 164 volumes of gas at STP• The potential amount of methane in natural gas hydrate is

enormous, with current estimates converging around about 10 terra tons (10^19g) of methane carbon.

• When methane hydrate production technology is established and commercialization is realized. It is expected to become a new domestic energy source that will significantly contribute to securing stable supplies of energy in world.

• Potentially this resource could be the back bone for the world’s energy sector during 21st century