india’s initiative towards exploration of shale gas & oil ... · • the neyveli lignite...

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: baleshk@yahoo.com

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