india’s initiative towards exploration of shale gas & oil ... · • the neyveli lignite...
TRANSCRIPT
India’s Initiative towards Exploration of
Shale Gas & Oil Shale and
Underground Coal Gasification
B. KUMARVisiting Consultant, RE-SOIL
CERS, Bharathidasan UniversityTiruchirapalli-620 023 INDIA
(Former Sct. G & Head, Surface Geochemical Prospecting and Carbon Sequestration, NGRI,Hyderabad)
Ph. 91- 9849934935 (O)91-40-27175910 (R)
E-mail: [email protected]
Initiatives comprise exploration and
exploitation of :
• Shale Gas
• Oil Shale
• Underground Coal Gasification
• Coal Bed Methane
• Gas Hydrates
Prognostic Resources of India’s
Unconventional Fossil Fuels
- Shale gas (?)
- Oil shale
(~15 billion tons of in place oil)
- Underground coal gasification
(Prog. resources ~ 15.5 tcm of natural gas)
- Coal bed methane
(Prog. resources ~20 tcf)
- Gas hydrates
(Prog. resources ~2000 tcf)
What is Shale Gas?• Shale gas is gas contained in adsorbed form in the micro-pores
and micro-fractures of shale which is a sedimentary rock.
The gas is mostly of thermogenic origin but cases of biogenic
sources are also reported.
• The shale gas exploration in India is relatively new but rapidly
gaining momentum, as India has huge shale deposits. The
shale in Vindhyan,Gondwana, Cambay,Rajasthan and other
sedimentary basins have been/are being field experimented. The
initial results are encouraging and on par with US producing
shale.
• The shale gas production pressures are generally low but length
of production period compensates by volume.
• Shale has low permeability (~ 2 md ) and gas does not flow easily through this
rock. However, in the 1990s a new drilling technology emerged. A tight shale
deposit could be cracked open by injecting water into wells at high pressure.
When the water injection stopped, the cracks closed again. But then
technologist hit on the idea of pumping water mixed with sand. The sand kept
cracks partially open when water injection stopped, increasing permeability and
gas flow.
• A sedimentary rock deposit has a limited depth but very wide area (sometimes
hundreds of square miles). Traditional vertical drilling into a deposit 20 meters
deep can yield gas production from a zone of just 20 meters. But new techniques
have facilitated horizontal drilling. This makes possible horizontal wells running
hundreds of meters long through shale strata, greatly increasing the production
zone of each well. Horizontal drilling plus sand cracking have revolutionized the
economics of shale gas in the US, and made it a developing industry.
Shale Gas Production Methodology:
Geological map of the Vindhyan Basin.
Vertical section showing occurrences of black shale and depositional trends within
the Vindhyan sedimentary succession (modified after Banerjee et al., 2006).
Vertical section showing occurrences of black shales and depositional trends
within the Vindhyan sedimentary succession (modified after Banerjee et al 2006).
TOC: 1.4 – 4.15 % ; S2 up to 0.14;
HI up to 4
TOC: 3.6 – 5.72 % ; S2 up to 0.05;
HI up to 4
TOC: 2.81 – 3.63 % ; S2 up to 0.02;
HI up to
TOC: up to 6.44 % ; S2 up to 0.03;
HI up to 2
Vertical log showing bottom shale, top shale and pyrite band in Bijaigarh Shale (a).
The Details of bottom shale and top shale are provided by two vertical logs in the right
by b and c, respectively (after Banerjee et al 2006).
Generalized geological map of Cambay basin.
After DGH, India
R&D Status of Shale Gas Exploration in
India
• ONGC has tied with Schlumberger to explore
shale gas in Gondwana and Cambay basins, India.
• The target areas in Gondwana are organic rich
shale horizons associated with unmineable coal
seams.
• In Cambay basin, the Tarapur and Cambay shale
formations are being explored for shale gas
potential.
� These are fine grained sedimentary rocks containing relatively large
amount of organic matter from which significant quantities of shale oil and
combustible gas can be extracted.
�Oil shale deposits range in age from Cambrian to Tertiary.
� Total world resources of in-place oil from shale is estimated at 2.6 trillion
barrels.
� Studies have shown that similar rocks with most of their oil generating
potential are preserved in Northeast India inter-bedded with the Tertiary
coal.
� The estimated in-place oil reserve of these carbonaceous shale deposits is
greater than 15 billion tons.
�Oil shale contains no liquid oil in its natural state and must be retorted at
very high temperatures to convert the solid kerogen to liquid
hydrocarbons.
�Retorting is an energy intensive process in which the rock is heated to
450- 550°C in the absence of oxygen.
Oil Shale
OIL SHALE OCCURRENCE in INDIA
• Carbonaceous shale of Oligocene age occurs in association
with Tertiary Coal in north east India, Assam and neighboring
areas of Arunachal Pradesh
• The coal-shale unit occurs as outcrops towards south of the
oilfields in a region called the Belt of Schuppen
• The presence of coal and organic rich shale has been
recorded in the subsurface from wells drilled for oil
• The coal-shale unit was probably deposited in a regressive
phase in backwater lagoons or brackish water swamps on a
prograding delta complex
Geological map of Northeastern part of Assam-Arakan Basin
Structural map of Assam-Arakan Basin
Source: DGH
Oil and gas fields and identified prospects in Assam geologic province
(modified from Naidu and Panda, 1997; and Mallick and others, 1997
Oil Shale Retorting
Surface Retorting
In-situ Retorting
� Studies of shale samples from Upper Assam Valley resulted in a total
hydrocarbon potential of 81 mg/g and compares favorably with yield
known from oil shale elsewhere in the world.
� North-East India is endowed with rich deposits of coal found in the
Barail Formation of Tertiary age.
� Carbonaceous shale occurs interbedded with the coal and constitutes
the principal source rock for hydrocarbons. These formations outcrop
on the surface towards the south of the oil fields in a region called the
Belt of Schuppen.
� Oil shale zones are part of the Barail and Disang formations of northeast
India. They are present over the area covered by Naga and Patkai hill
ranges.
� The calculated in-place shale oil reserve is greater that 15 billion tonnes.
Salient features of oil shale in North East India
• Oil shale deposits usually include certain amounts of
carbonates. Due to the decomposition of carbonates, oil
shale evolves several times more CO2 during shale oil
production than the same amount of petroleum
production does. This could be a serious defect from the
view point of global warming.
• Deep Coal seams of North East India, which are not
commercially viable for coal production, could be used for
permanent underground storage of CO2 evolved from
shale oil production
• CO2 released from oil shale can be used for Enhanced Oil
Recovery in depleted oil fields of North East India.
Carbon management for oil shale of NE, India
What is UCG?
An in-situ physico-chemical process of converting of
unmineable coal / lignite into a combustible product
gas (fuel gas).
• The product gas is a mixture of hydrogen, carbon
monoxide, methane, carbon dioxide & higher
hydrocarbons.
• Calorific value of product gas is in the range of 700 to
1200 KCal/NM3 for gasification with air injection.
Product Gas of UCG
UCG Process
The process involves:
• Drilling two boreholes (>100 m deep) in the coal seam,
one as the injector and the other as producer, placed
adjacently.
• Linking the bore holes
• Ignition of coal seams down hole
• An underground gasifier is made up of a number of
underground reactors with largely independent outputs.
The gas streams from different reactors can be mixed
as required to ensure consistency of overall gas quality.
The outputs of reactors can be varied in order to optimize
coal extraction and gas supply from the gasifier.
• Ground water influx into the gasifier creates an
effective "steam jacket" around the reactor making the
heat loss in situ tolerably small.
• Optimal pressure in the underground gasifier promotes
ground water flow into the cavity, thus confining the
chemical process to the limits of the gasifier and
preventing contamination in the area.
• Product gases are recovered from second hole. Drilling
and connecting additional injection and production
wells can readily expand the initial gasification reaction.
Why UCG?
Typically, coals of low rank e.g. lignite and sub-bituminous are
the easiest to gasify, hence better suited for UCG. Underground
Coal Gasification offers a potential means of extracting energy
from deposits, which will not be amenable to conventional
mining, economically.
India is endowed with vast coal and lignite resources of around
248 and 36 billion tonnes, respectively. A major portion of these
resources occur at relatively deeper depths or are constrained by
one or more factors for commercial mining.
In view of the above, a non-conventional technology such as UCG
has opened up new avenues for harnessing the vast potential of
these resources, thus enhancing the energy security of the
country.
India's Coal Reserves
2478473779711709092960Total
2781345541187611383West Bengal
10620296766Uttar Pradesh
60984148473097615161Orissa
201514Nagaland
45930141117Meghalaya
8582162023094653Maharashtra
19232290488157513Madhya Pradesh
7220463483043935417Jharkhand
399754411261919373Chhattisgarh
16016000Bihar
3403427279Assam
90194031Arunachal
Pradesh
16926258460798263Andhra Pradesh
TotalInferredIndicatedProved
Coal Resources in Million TonnesState
2478473779711709092960Total
2781345541187611383West Bengal
10620296766Uttar Pradesh
60984148473097615161Orissa
201514Nagaland
45930141117Meghalaya
8582162023094653Maharashtra
19232290488157513Madhya Pradesh
7220463483043935417Jharkhand
399754411261919373Chhattisgarh
16016000Bihar
3403427279Assam
90194031Arunachal
Pradesh
16926258460798263Andhra Pradesh
TotalInferredIndicatedProved
Coal Resources in Million TonnesState
2478473779711709092960Total
907369106432Tertiary Coals
2469403742811698492528Gondwana
Coals
TotalInferredIndicatedProved Formation
2478473779711709092960Total
907369106432Tertiary Coals
2469403742811698492528Gondwana
Coals
TotalInferredIndicatedProved Formation
Proved world coal reserves at the end of 2006
UCG Potential In India
• India has very large deposits of deep seated coal and
lignite which are unmineable using conventional
mining methods.
• The revised reserves of coal are 253,359 million
tonnes (GSI,report) and the estimated recoverable
reserves are ~ 95,866 million tonnes, i.e 37.8%.
• Lignite resources of the country are 37,154 million
tonnes (GSI,report). The estimated recoverable
reserves are ~ 4, 260 million tonnes, i.e 11.5%.
INDIA & WORLD
• There are over 5 million PJ (petajoules) of resource for UCG
gas in the United States, 2.2 million PJ of UCG gas in China,
and 1.9 million PJ of UCG gas in India.
• The Lawrence Livermore National Laboratory (USA) has
estimated that recoverable reserves could be increased by at
least 300% to 400% and that 1.6 trillion tons of unmineable
coal in the USA may be recoverable with UCG.
CHINA • China has over 50 large coal gasification facilities nationwide.
• China has executed at least 16 pilots since 1991, and has
invested in extensive research programs at China University of
Mining Technology in Beijing.
AUSTRALIA • The World Energy Council’s 2007 Survey on Energy resources
estimates that 45% of Australia’s proven in place reserves, or 44
billion tonnes, is available for extraction by UCG.
• Applying this same proportion to Queensland’s measured plus
inferred sources of thermal coal, suggests that there are
possibly 16 billion tonnes that may be available for UCG in
Queensland.
UCG potential in India
UCG IN INDIA• The Neyveli Lignite Corporation Ltd. (NLC), which has Government approval
for taking-up a UCG Project in lignite deposits of Rajasthan, is looking for a
suitable technical partner for UCG.
• The Reliance Industries Limited (RIL) has been exploring possibilities for
taking up UCG projects in India.
• ONGC, while drilling in search of hydrocarbons, discovered large reserves of
coal at depths more than 600m. These are spread in Gujarat and West Bengal
and have been estimated to contain more than 350bt of coal deposit.
• In Gujarat alone, these coal reserves have been estimated to be around 70 bt
in Mehsana-Ahmedabad block and 60 bt in Patan-Tharad block.
• The energy estimated for Mehsana – Ahmedabad block alone, is equivalent to
about 15,000 bcm of natural gas.
• The ONGC is conducting a pilot test in Mehsana area at an estimated cost of
Rs 9.60 crores.
• An Information Well – UCG-1 – was drilled as early as in 1986 to a depth of
1005m at the selected site.
ESTIMATED RESERVES FROM WEC 2008
POSITIVE FACTORS
1. UCG is the only feasible technology that enables exploitation
of deep (> 700m) coal reserves, which are not amenable to
known conventional mining methods.
2. UCG offers an environmentally clean way to harness energy from
coal.
3. UCG brings no solid waste to the surface.
4. Even at shallower depths (< 500m), UCG can be more
economical than conventional mining.
5. UCG reduces capital investment, operating costs, and the output
gases cost by 25 to 50% as compared to surface gasification.
6. Possibility of transport of medium calorific value gas over a
distance of 100 km exists.
7. Possibility of using CO2 from the gas for enhanced oil recovery
exist.
8. Basic UCG technology is known.
9. Conditions in India are far more compelling for adopting UCG
than most locations in the world.
ADVANTAGES
• Much higher coal extraction – up to 95%
• Multiple seams
• Thick and thin seams
• More economic – less capital expenditure
• Economic on a smaller scale
• Potential to be cleaner technology – smaller
• Environmental footprint
• Little or no rehabilitation required
• No fine coal and Ash
• Safer
DISADVANTAGES
• Potential for contamination
• Controlling ability of the reaction
The Coal Bed Methane,
Prognostic resources
for India ~ 20 tcf
DGH, Annual Report, 2006-07
Density of CO2 and CH4 as a function of pressure for various
Temperatures based on data from Vargaftik et al. (1996).
DGH, Annual Report, 2006-07
Enhanced Coal Bed Methane Recovery (ECBM)
Coal beds typically contain large amounts of methane rich gas that is
adsorbed onto the surface of the coal. The injected CO2 efficiently
displaces methane as it has greater affinity to the coal than methane.
CO2 enhanced
coal bed
methane
production
Location in the Eastern Offshore, superimposed on Gas Hydrate stability
thickness map along the Indian margin, from where the gas hydrate samples
have been recovered.
(after Sain & Gupta, 2008)
Possible production methods for Gas Hydrates
(after Holder et.al., 1984)
CO2Sequestration in Methane Hydrates
� Methane Hydrates are class of solids in which methane
molecules occupy cages made up of hydrogen- bonded
water molecules.
� CO2 can also be stored as hydrates with simultaneous
conversion of in situ methane hydrates into natural gas.
� At temperatures below 10°C, there is a pressure range
in which methane hydrate is unstable while CO2 hydrate
is stable.
� The heat released from the formation of CO2 gas hydrate
is greater than that needed for CH4 hydrate
dissociation:
CH4(H2O)n ⇒ CH4 + nH2O; Hf = 54.49 KJ/mole
CO2(H2O)n ⇒ CO2 + nH2O ; Hf = 57.98 KJ/mole
where n is the hydration number for CH4 hydrate and
CO2 hydrate
� n is dependent on pressure, temperature and the
composition of the gas in the gas phase which implies
that under certain pressure and temperature conditions,
the replacement of CH4 in the hydrate with CO2 is
thermodynamically possible.
After Gas Technology Institute, USA
SEDIMENTARY BASIN MAP OF INDIA Category Basin Basinal Area (upto 200m (Sq.Km.x 103)isobath)
I Cambay 53Assam Shelf 56 Bombay Offshore 116Krishna Godavari 52Cauvery 55Assam-Arakan 60Rajasthan 126
II Kutch 48Andaman-Nicobar 47
III Himalayan Foreland 30Ganga 186 Vindhyan 162Saurashtra 80Kerala-Konkan-L.dweep 94Mahanadi 69Bengal 89
IV Karewa 4Spiti-Zanskar 22Satpura-Rewa-Damodar 46Narmada 17Deccan Syneclise 273Bhima-Kaladgi 9Cuddapah 39Pranhita-Godavari 15Bastar 5Chattisgarh 32Total 1,785
Deep WatersKori-Comorin850 ENarcodam 1,350
Source: DGH
India’s Hydrocarbon Resources,
Reserves & Production
• Total hydrocarbon resources of India, inclusive
of deep waters, are estimated at around 28
billion tonnes oil & oil-equivalent of gas.
• As on April 2008, the ultimate reserves of oil &
oil-equivalent of gas established are 3.37 billion
tonnes.
• The oil and gas production accounts to be 34.13
(MMT) and 32.40 (OEG,MMT), respectively.
Exploration and exploitation of
unconventional fossil fuels (shale
gas,oil shale, underground coal
gasification, coal bed methane
and gas hydrates) are the key to
India’s Energy Future and
Security.
Conclusion