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Underground Coal Gasification
• COALIFICATION PROCESS
• GASIFICATION PROCESS
• UNDERGROUND (IN SITU) PROCESS
…. covers
Underground Coal Gasification
• COALIFICATION PROCESS
• GASIFICATION PROCESS
• UNDERGROUND (IN SITU) PROCESS
Underground Coal Gasification
CHEMICAL COMPOSITION OF COAL
Fuel C H O N
Wood 49.65 6.23 43.20 0.92
Peat 55.44 6.28 35.56 1.72
Lignite 72.95 5.24 20.50 1.31
Bituminous 84.24 5.55 8.69 1.52
Anthracite 93.50 2.81 2.72 0.97
Clarke
Underground Coal Gasification
CHEMICAL COMPOSITION OF COAL
Rank Moisture Vol.
Matter
Fixed
Carbon
Ash
Lignite 34.55 35.34 22.91 7.20
Sub-
Bituminous
24.28 27.63 44.84 3.25
Bituminous 3.24 27.13 62.52 7.11
Semi-
Anthracite
3.38 8.47 76.65 11.50
Anthracite 2.80 1.16 88.21 7.85
After Moore
Underground Coal Gasification
COAL PROD VS. CONSUMPTION
-
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
-
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0Prod (Million Ton OE)Consumption (Million Ton OE)
Underground Coal Gasification
WORLD PRIMARY ENERGY
CONSUMPTION
9124.8 594.5 601.2 2255.1 2164.3 3510.6 WORLD
335.2
5.8
38.7
84.4
74.6
131.6 Germany
514.5
20.4
72.7
103.0
71.1
247.2 Japan
643.0
39.8
30.9 114.6
335.4
122.3 Russia
314.7
16.1
4.4
173.5
23.7
97.1 India
839.7
58.3
4.0
520.6
24.9
231.9 China
2237.3
48.3
183.2
555.7
554.6
895.6 USA
Total Hydro
electric
Nuclear
Energy
Coal Natural
Gas
Oil Million
tonne oil
equivalent
India is the 3rd largest coal consumer of the world
R/P : 246 years
Underground Coal Gasification
• COALIFICATION PROCESS
• GASIFICATION PROCESS
• UNDERGROUND (IN SITU) PROCESS
Underground Coal Gasification
CARBON/COAL GASIFICATION
REACTIONS
Partial Combustion C + O2 = 2CO exothermic
Combustion C + O2 = CO2 exothermic
C + CO2 = 2CO endothermic
Water-Gas C + H2O = CO + H2 endothermic
Hydrogasification C + 2H2 = CH4 exothermic
Shift CO + H2O = CO2 + H2 exothermic
Reformation CO + 3H2 = CH4 + H2O exothermic
Underground Coal Gasification
MATERIAL BALANCE
AIR GASIFICATION
H2O - (153.9)
C - 1000
H - 79.6
O - 230.8
N - 13.3
Underground Coal Gasification
MATERIAL BALANCE
GASIFICATION WITH O2+H2O liq
H2O - (153.9)
C - 1000
H - 79.6
O - 230.8
N - 13.3
Underground Coal Gasification
MATERIAL BALANCE
GASIFICATION WITH O2+H2O Steam
H2O - (153.9)
C - 1000
H - 79.6
O - 230.8
N - 13.3
Underground Coal Gasification
• COALIFICATION PROCESS
• GASIFICATION PROCESS
• UNDERGROUND (IN SITU) PROCESS
Underground Coal Gasification
UNDERGROUND COAL
GASIFICATION
A process to convert
unmineable under-ground
coal/ lignite into
combustible gases by
gasifying the coal insitu
Underground Coal Gasification
ESSENTIAL STEPS IN UCG
• Drill wells into coal seam
• Create a permeable link
path
• Ignite coal at bottom
• Inject air (or oxygen) to
sustain fire
• Remove product gas
through production well
• Clean product gas in
surface facilities for end
use
Underground Coal Gasification
.. where we STAND..
.. what we SEE..
.. what we FACE..
.. what we SEEK..
Underground Coal Gasification
UCG REACTORS - WORLD
Site Depth (m) Year Gas Produced
(Million m3)
Podmoskovna 30-80 1947-62 4700
Lissichamskaya - 1948-62
Angren 120-200 1962-current 14000
Juzno-Abinskaja 50-300 1955-current 6700
Schatska - 1965-74
*Russian Fields
Underground Coal Gasification
UCG REACTORS - WORLD
Site Depth (m) Year Gas Produced
(Million m3)
Hanna 85 1973-79 63.56
Hoe Creek 50-120 1976-79 12.18
Price Town 270 1979 1.39
Rawlins 30 1979-81 17.35
Centralia 75 1983 1.78
Hanna ( Rocky
Mt.1)
110 1987-88 13.10
USA fields
Underground Coal Gasification
UCG REACTORS - WORLD
Site Depth (m) Year Gas Produced
(Million m3)
Bruay-en-
Artois (France)
65 1978-81
La aute Deule
(France)
60 1979-85
Thulin
(Belgium)
860 1986-87 0.55
Alcorisa
(Spain)
500-700 1990 -
European fields
Underground Coal Gasification
WHY UCG IN INDIA
• Exploitation of huge unmineable
coal reserves (123 billion tonnes) in
Gujarat alone
• Transportation of coal to existing
power station: Severe strain on
railways
• Environmentally clean technology
Underground Coal Gasification
WHY UCG IN INDIA
• Use of produced gas for power
generation or for chemical feed-
stocks
• Potential use of carbon di-oxide for
Enhanced Oil Recovery (EOR) exists
in the area
Underground Coal Gasification
UCG POTENTIAL IN INDIA
POTENTIAL AREAS SOBHASAN, KALOL AND MEHSANA CITY STRUCTURE OF NORTH GUJARAT
ESTIMATED COAL/ 123 BILLION TONNES
LIGNITE RESERVES (700-1700 M DEPTH)
EXPECTED ENERGY EQUIVALENT TO ABOUT 15000 BILLION M3 OF NATURAL GAS (Meh-Ahm Block)
Underground Coal Gasification
UCG POTENTIAL
GSI
234 Bt coal
(Around 150 Bt at
unmineable depth)
ONGC
>350 Bt (Unmineable depth)
63 Bt in
Mehsana-
Ahmedabad
Block
60 Bt in
Patan-
Tharad
Block
>200 Bt in
Bengal
Basin
Equivalent to
15000 Billion m3 of Natural Gas
10%
Equivalent to 1.35 times of
O+OEG reserves of ONGC
Underground Coal Gasification
EXPERIENCE IN UCG PROJECT
In mid 80’s a UCG National Committee was set up
to look into the UCG project wherein ONGC was
the nodal agency
• Proposed site was in Mehsana city structure
• Two Information wells were drilled
• Hydrological studies conducted
• Core studies conducted
Underground Coal Gasification
EXPERIENCE IN UCG PROJECT
• 3-D Seismic survey carried out
• Prepared Geological model
• Design pilot wells
Underground Coal Gasification
GENERAL PROPERTIES FOR
FAVOURABLE UCG SITE
• Thickness of 3 to 10m
• Steeply dipping - (Flat lying acceptable)
• Strong, dry roof rock
• Coal seam shall not be major aquifer
• No major aquifer over coal seam at least twice of stable cavity height
• Low natural permeability of formation
• No major faults or fractures
• Amenable topography
• Proximity to end user market
Underground Coal Gasification
UCG PILOT PROJECT IN INDIA
• PILOT PROJECT SITE : MEHSANA CITY
STRUCTURE
• TARGET COAL SEAM : SOBHASAN - III
• DEPTH OF COAL
SEAM : 900-1100 M
• THICKNESS OF COAL
SEAM : 6-14 M
• TYPE OF COAL : LOW RANK SOFT,
DARK BROWN
LIGNOBITUMINOUS
Underground Coal Gasification
UCG PILOT PROJECT IN INDIA
The objectives were: • To demonstrate the feasibility of UCG at deeper
depth
• To demonstrate drilling of long in-seam holes and to connect hole with vertical well
• To develop gasifier initiation and cavity growth control techniques
• To monitor and measure gasifier development
• To know product gas quality and quantity
• To prove material capabilities and environmental impact
Underground Coal Gasification
UCG PILOT PROJECT IN INDIA
The pilot could not be executed due to
• Limited expertise available then
• Non-availability of OIDB funds
Underground Coal Gasification
PHYSICAL REQUIREMENTS
• Characteristics of coal/lignite seams (Chemical
analysis, pyrolysis, through tube coal
experiments)
• Characteristics of roof and floor rocks
(Mechanical properties for prediction of cavity
formation and subsidence)
• Hydrological studies and gas migration studies
• Pollution studies (Air and Water) before and after
gasification
Underground Coal Gasification
TECHNOLOGICAL
REQUIREMENTS
• Drilling, Special cementing, Design and
Completion of Process wells
• Combustion process package ( Ignitor, Cavity
formation, Propagation)
• Process of CRIP (Controlled Retracting Injection
Point)
• Surface design for UCG
Underground Coal Gasification
Participation Required
• Resource Characterisation
– Coal Seam Properties
– Hydrologic Characteristics
• Laboratory investigations of coal properties
• Laboratory Gasifier experiments
• Reaction Kinetics
• Subsidence studies
• Detailed Engineering design of pilot
• Development of process options for UCG product Gas cleanup.
• Simulation of underground process
…… and lot more
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