gas hydrates its formation and recovery.

1. GAS HYDRATE:
A BURNING ICE
By
Ritesh & P.Durga
2nd Year
Petroleum Engineering

2. What is a Gas Hydrate?
•Gas Hydrates are solid mixture of natural gas and water
•Gas molecules are encaged between ice lattices.
(85 : 15 :: water : gas molecules)
•Contains 160-180 times the natural gas by volume at
standard conditions.

3. HYDRATE SAMPLES
Gas hydrates in sea-floor mounds Here methane gas is
actively dissociating from a hydrate mound.
Gas hydrate can occur as nodules, laminae, or veins within sediment

4. Ice That Doesn’t Melt !
•Formed at low temperatures and high pressure.
•Known to occur at temp. below 295K and pressure
greater than 3000KPa.
•Water molecules attach themselves through hydrogen
bonding and form cavities which are occupied by a
single gas or volatile liquid molecule.
•Gas or volatile liquid inside the water cage stabilizes the
structure through physical bonding via weak van der
Waals forces.

5. Hydrates occur when water molecules attach
themselves together through hydrogen bonding and
form cavities which can be occupied by a single gas or
volatile liquid molecule.
The presence of a gas or volatile liquid inside the water
network thermodynamically stabilizes the structure
through physical bonding via weak van der Waals forces.
Hydrates are known to occur at temperatures less than
295 K and pressures greater than 3000 KPa i.e. at low
temperature and high pressure.
Whether or not gas hydrate actually forms depends on
the amount of gas available.

6. Gas Hydrate Potential
Worldwide Estimate of Gas Hydrates
•700,000 Tcf (20,000 trillion cubic meters)
•Conventionally recoverable methane 8,800 Tcf ( 250
trillion cubic meters)
•Two times the total energy in coal oil and conventional
gas.
If 1% of gas –in-place in gas hydrate is recoverable : 2000 Tcf

9. Stability Zone In Sea
Found inside sea at depths greater than 500m and at
temperatures even higher than those for ice stability.
Stable in association with permafrost in the polar
regions, both in offshore and onshore sediments.

10. • Gas hydrates are stable at the temperatures
and pressures that occur in ocean-floor
sediments at water depths greater than
about 500 meters, and at these pressures
they are stable at temperatures above those
for ice stability.
• Gas hydrates also are stable in
association with permafrost in the polar
regions, both in offshore and onshore
sediments.

11. Why is it urgent to be studied ?
•A future energy source
•Climate change
•It can affect sediment strength, which can
initiate landslides on the slope and rise.

12. •Hydrate is a gas concentrator; the breakdown of a
unit volume of methane hydrate at a pressure of one
atmosphere produces about 160 unit volumes of
gas.(The worldwide amount of methane
in gas hydrates is considered to contain at least
1x104 gigatons of carbon in a very conservative estimate).
•This is about twice the amount of carbon held in
all fossil fuels on earth.
A Future Energy Source … Continued

13. •When hydrate fills the pore space of sediment, it can
reduce permeability and create a gas trap, The gas can
continually migrate upwards to fill any open pore
spaces.
•This process, in turn, causes the trap to become more
effective, producing highly concentrated methane and
methane hydrate reservoirs.
A Future Energy Source

14. •Methane is an environmentally cleaner fuel than
oil, coal, or oil shale which all have an immense
environmental impact during production and
combustion.
•We can find a way to trap carbon dioxide at the
seafloor where it would eventually be buried by
sediment.
Climate Change … continued

15. •Methane from the hydrate reservoir might
significantly modify the global greenhouse, because
methane is ~20 times as effective a greenhouse gas
as carbon dioxide, and gas hydrate may contain
three orders of magnitude more methane than exists
in the present-day
atmosphere.
•Because hydrate breakdown, causing release of
methane to the atmosphere, can be related to
pressure changes caused by glacial sea-level
fluctuations, gas hydrate may play a role in
controlling long-term global climate change.
Climate Change

16. Present Day Techniques
1. THERMAL INJECTION
2. INHIBHITORS
3. DEPRESSURISATION
Courtesy :slb

18. PRODUCTION OF GAS HYDRATES

19. PROBLEMS WITH PRESENT DAY
TECHNIQUES
 Thermal injection – Unavoidable heat losses due to host
rock, economical infeasibility.
 Depressurization – Endothermic nature causing decrease in
reservoir temperature.
 Inhibitors – methanol and ethylene glycol are expensive
chemicals.

20. Production well
Antenna
(micro waves)
Gas hydrate reservoir
New concept
diagram of reservoir.
Injection well

21. STEPS INVOLVED
Release of microwaves (@2450Mhz).
Melting of gas hydrate or ice .(Temp. > 273 k )
Injection of Fluorine.
Reaction between methyl radical and injected fluorine gas
(halogenation).
CH
.
3 + F2 = CH3F( -431KJ/mole)
(Solubility of methyl fluoride(166cc in 100ml of water))
Recovery of liquefied gas hydrate solution.
Step 1: Wurtz Reaction
2 CH3F + Na ----- 2 NaF + CH3-CH3
Step 2 :Electrolysis
NaF ----- Na + 1/2 F2 ↑
Step 3 :Cracking
CH3-CH3 ------ 2 CH4 ↑

22. ADVANTAGES WITH RESPECT
TO NORMAL TECHNIQUES
•Cost effective ,instantaneous and selective heating,
catalyze chemical reaction.
•Methyl fluoride is not an class 1 or 2 ozone depleting
chemical and stable compound.
•Huge reduction in disaster on rig floor or drill floor
related issues.
•Increase in the permeability and porosity of rock.

23. CHALLENGES
•Fluorine is highly electronegative and
reactive in nature e.g. injection problems.
•Transportation of methyl fluoride solution.

24. CONCLUSION
•Huge amount of natural gas trapped in hydrates : too
enormous to ignore.
•It’s a threat to climate as well so there is an urgent
need that we use it for positive purpose.
•Technology and scientific understanding for exploitation
of gas hydrate is to be developed .
•Much to be learned before gas hydrates can be
considered a resource.
•The integration of various sciences and using the
fluorine in this technique will definitely play a vital role
in the methane extraction.

25. REFERENCES
• www.spe.org
•http://en.wikipedia.org
•http://www.cbc.ca
•http://Petrowiki.org