16 Fuel Geology

Pankaj Mehta

Objectives:

 

  1. To understand the process of formation, importance and occurrence of non-renewable energy resources (coal, petroleum and natural gas) in Indian subcontinent.
  1. To understand the status of Fossil Fuel in Indian and Global scenario to quantify its future and Global Energy Demand
  1. To understand how Coal Bed Methane (CBM) is formed, and its status in Indian subcontinent and alternate renewable energy resources.

 

1.1 Study of Non-Renewable Energy Resources of Earth

 

The buried combustible geologic deposits of organic material which had been compressed under the layers of rock in the earth and beneath the oceans for millions of years are termed as fossil fuel.

The first man who introduced the theory of fossil fuel was Georgius Agricola.

Fossil fuel are of tremendous importance in the existing scenario as they acts as a feeding mechanism for all the power plants (coal and gas based), needed for the transportation industry, steel and cement industry and many others.

The fossil fuel are non-renewable resource of energy on ecological time scale but are renewable on geological time scale.

 

1.2 Formation and Composition of Coal

 

The word “Coal” originates from the Anglo-Saxon word “Col”, which means charcoal.

Coal is formed from plant remains that have been compacted, hardened, chemically altered and metamorphosed by heat and pressure over geologic time.

Aggregate of macerals the smallest particle (eg. Vitrinite, Fusinite, Exinite etc.) constitute the coal.

Indian Coal is of sub-bituminous to Bituminous quality formed during the Carboniferous period of Paleozoic era approximately 300-million years ago.

 

Coal has remained the   dominant fuel in India with 54.5% of total consumption.

The Coal India Ltd (CIL), a public sector entity, is the world’s largest coal producer and produces 80% of India’s coal.

 

In Coal, carbon forms more than 50% by weight and more than 70% by volume, other constituents of coal include mineral matter, usually silicates minerals such as clays, illite as well as carbonate mineral such as siderite, and aragonite.

 

1.3 Classification of Coal

 

Depending on the amount and type of carbon it contains, and the amount of heat it produce:

 

  1. a) Anthracite ( Highest quality coal having 90% carbon content)
  2. b) Bituminous (Moderate quality coal having 50-70% carbon content)
  3. c) Lignite (poor quality coal having 30% carbon content also called “brown coal”)
  4. d) Peat (First stage of Coal formation, very low quality carbon content only 5-10%)

 

1.7 Global Coal Scenario

 

World coal production has increased by around 0.8%.

Indonesia recorded the highest increment by 9.4% followed by Australia at around 7.3% with a decline in USA of 3.1%.

Coal provides around 30% of global primary energy needs and generates over 40% of the world’s electricity and is used in production of 70% of world’s steel.

Top coal producers in 2015 were China (3,650MT), USA(916MT), India (668MT), Australia(491MT), Indonesia (471MT), Russia(334), South Africa(253MT) and Germany(187MT).

 

1.8 Exploration of coal in India

 

On the recommendation of coal committee for systematic survey of coal fields, Geological Survey of India (GSI) initiated search for coal in the year 1845.Exploration for coal by drilling started since 1869. Geophysical techniques were introduced in coal exploration during the late 1940s. The various important acts which are related to coal are as follows:

 

 

The Coal Bearing Areas Acquisition and Development Act (CBAADA), 1957.

The Mineral Concession Rules (MCR), 1960.

The Coal Mines( Nationalisation) act,1973

The Colliery Control Order,1945.

2.0 Petroleum & Natural Gas

Petroleum (rock oil or crude oil) is a naturally occurring, yellow to black liquid found in sedimentary geological formations beneath the earth surface rich in organic matter 0.5 to 2% by weight. It is an admixture of various hydrocarbons and is also known as black gold. Most oil and gas starts it’s life as microscopic plants and animals that live in the ocean.

 

2.1 Origin of petroleum:

 

Petroleum is of organic origin. It originate from the slow decomposition of lower forms of marine organism such as foraminifers, diatoms, algae, ostracodes etc. in offshore sedimentary basins where huge amount of organic matter is deposited along with muddy sediments under reducing condition protecting organic matter from oxidation, under such conditions anaerobic bacteria extract oxygen from the organic matter and transform it into fatty and waxy substances, during the millions years of deep burial, the organic matter is converted into oil by the slow chemical reaction. The factors which play an important role in the formation of petroleum are lower form of marine life, pressure, moderate temperature and great length of time. Where sediment contains more than 5% organic matter, it eventually forms a rock known as a Black Shale, as Black Shale is buried, with progressive heating of the organic material it undergoes chemical and physical changes and at a temperature of around 30°C, a solid, sticky bitumen is produced which is known as kerogen, which is a solid form of hydrocarbon, around 90°C liquid oil is formed and as temperature reaches upto 150°C, it results in the production of natural gas like methane. A Black Shale that is heated and gives off oil and gas is known as the “Source Rock”. Hot oil and gas is less dense than the source rock in which it occurs. Oil and gas migrate upwards up through the rock in much the same way that the air bubbles of an underwater diver rise to the surface. The possible cause for migration are; a) compaction of source rock b)Buoyancy effect c)Capillary effect and d)water flushing.

2.3 Petroleum Reservoirs in India

In India reservoirs of petroleum are found in the belts of tertiary rocks of Assam, Gujarat, offshore regions of Bombay high and in Cauvery and Godavari deltaic areas. Oil fields of Assam, includes Digboi, Nahorkatiya, Moram, Rudrasagar and Lakwa oil field however oil field of Gujarat, includes Ankleshwar, Cambay, Kalol and Nawagam oil field. Bombay high is the richest deposit of petroleum in the country.

 

2.5 Oil and Natural Gas Exploration in India

 

Oil exploration in India began in 1867 when oil was struck at Makum, near Margherita in Assam, however exploitation and production was systematically started in 1899 with the formation of Assam Oil Company (AOC). The Oil and Natural Gas Commission (ONGC) which was set up in 1955,was finally transferred into commission in 1956. ONGC is the Asia’s largest and most active companies involved in exploration and production of oil. It is headquatered in Dehradun.

2.6 Global Petroleum Scenario

World consumes 83,607,221 barrels of oil each day, as per report of 2005, during the past 10yrs proven reserves have risen by 27% (more than 350 million barrels), but the annual report of 2013 says, Earth has nearly 1.688 trillion barrels of crude which will last for 53.3 yrs at current rate of extraction so there is an immediate need that world should switch over to alternate source of energy.

 

World top producer of petroleum in the year 2016 are :

 

a) Saudi Arabia

b) Russia

c) United states

d) Iraq

e) China

f) Canada

g) Iran

h) UAE

i) Kuwait

j) Venezuela

 

2.7 India’s Petroleum Scenario:

 

Petroleum resource provides about 34% of world energy needs. India is one of the largest importer of petroleum products in the world and ranks at 20th position in production of petroleum in the world with 9000km of crude oil pipelines. The total consumption of petroleum are rising day by day and from past five years the consumption rate has gone up at a rate of 2.8%.

3.0 Natural Gas

 

Natural gas is a naturally occurring hydrocarbon gas mixture, containing methane and varying amount of other alkanes and sometimes small percentage of carbon dioxide, nitrogen, hydrogen sulphide or helium.

 

3.1 Formation of Natural gas

 

The formation of natural gas takes place when the layers of decomposed plants and animals are exposed to intense heat and pressure under the surface of earth over millions of years. The energy that the plant originally obtain from the sun is stored in the form of chemical bonds in the gas.

Two mechanism are involved for the formation of natural gas; a)  Biogenic b) Thermogenic

Biogenic gas is created by methanogenic organism in marshes, bogs, landfills and shallow sediments deep inside the earth however thermogenic gas is created by buried organic matter. Most oils are produced at temperature between 60˚C to 120˚C (the oil window) and above this temperature petroleum is transferred into Natural gas.

3.2 World’s   Natural Gas Scenario:

 

Natural gas is third prominent energy resource amounting to 23% of global energy consumption. The world’s Natural gas reserves are estimated to 10,000 trillion cubic meters out of which only 6,186 TCF are proven. Russia is the top producer of natural gas followed by Iran, Qatar, Saudi Arabia, and UAE.The global market for gas is much smaller than oil because gas transport is costlier and difficult only about 16% of global gas production is internally traded. Middle east and Africa are likely to be main contributor for the supply of gas in near future as they have tremendous growth.

 

3.3 Natural gas scenario in India

 

The development of Natural gas industry in the country started in 1960s, with the discovery of gas fields in Assam and Gujarat. The exploration activities were carried out earlier by National Oil companies (ONGC & OIL) and later private companies were allowed to enter into exploration. The production of natural gas in India recorded decline in the last four year. The production in 2013-2014 declined by 13% as compared to 2012-2013. India has 15000kms long natural gas line at present and an announcement is made to extend 15000kms more pipeline in twelfth five year plan period. Natural gas has an added advantage over coal and petroleum as it act as a cleanest fuel with less carbon dioxide emission, as compared to coal and petroleum it also act as raw material for common product like paints, fertilisers, antifreezez, dyes, photographic films etc.

 

4.1 Coal Bed Methane

 

Coal bed methane(CBM) is a natural gas extracted from coal beds of conventional reservoirs. Methane is associated with coal as a by-product of the coal formation process which is trapped in coal beds and released during and after coal mining. It is also called sweet gas because of its lack of hydrogen sulphide. The pressure exerted by the naturally formed water keeps the methane absorbed on internal surface of coal making coal bed gas to exist in a monomolecular state and not as a free gas as a result which all the coal fields of the world have coal bed methane, porosity of the earth materials plays an important role in building up of methane gas reserves in the coal beds. Coal bed methane has become a good source of clean thermal energy because of its easier inflammmability. The major coal basins from where it comes are especially in countries like USA, Australia and China.

 

4.2 Coal bed methane (CBM) exploration in India

 

In India prospects for coal bed methane are not high because the Indian coal is of sub-bituminous to bituminous quality however some of the coal basins in India contains high quality coal where sizeable reserves of CBM are expected for eg. Godwana coal field, the tertiary coal of Makum area, Assam and thick lignite of Tamil Nadu and Gujarat. Government of India approved a comprehensive CBM policy and strategy in 1977 for effective harness and exploration of coal bed methane (CBM) gas, so far 33 blocks have been awarded to companies in Jharkhand, West Bengal, Chattisgarh, Madhya Pradesh, Rajasthan and Assam for the exploration and production of CBM. The planning commission (2011) has projected the total CBM production to be 1256 MMSCM in 2016-2017, however CBM Production in past has not met its projected plan.

 

Global Energy Demand(1990-2035)

 

 

 

Alternative to Fossil Fuel:

 

As it is visible from the graph shown in Fig.4(a) it is obvious that there is need to switch over from non-renewable resource of energy towards renewable resource of energy for a sustainable and a better future which includes to harness more and more energy using solar, wind, hydro and geothermal energy as potential source of renewable energy resources to combat the energy crisis.

 

Conclusion:

 

In this lecture we learnt about:

 

  • ü Process of formation of Coal, Petroleum and Natural Gas.
  • ü Importance and Distribution of Coal, Petroleum and Natural Gas in Indian subcontinent.
  • ü Indian and Global scenario of Petroleum and Natural Gas
  • ü Coal Bed Methane and its exploration in India
  • ü Global energy demand and future of non-renewable energy resource (coal, petroleum and natural gas).

 

References:

 

  • BPCL, Annual report,2014
  • Energy Information Administration, Internal energy, Outlook, 2010
  • https://en.wikipedia.org/wiki/Coal
  • https://en.wikipedia.org/wiki/Petroleum
  • Ministry of Oil & Natural Gas, BMI forecasts, Tech Sci Research
  • TERI 2014 a; MoPNG (2014a, 2014b)
  • US Energy Information Administration from Oil and Gas Journal 2007