Unit1.pdf

Unit 1

1 Notes

Basic Concepts Objectives After reading this unit, you will be able to: y Understand what is petroleum, what are its constituents, and their significance. y Know about composition and characteristics of oil and gas. y Understand what are the main products from oil and gas and their uses. y Get familiar with some of the common concepts, definitions and terminologies used with respect to oil and gas.

Introduction Oil industry is perhaps the most exciting industry in the history of civilization. Although the history of oil traces back to seepages of oil as early as 3000 B.C., the real thrill of it started with the oil boom in the USA. When Rockefeller was asked to tell very briefly how people get rich, he replied “Some people find oil, some don't”. It's amazing how much oil and gas has penetrated into our lives today. The toothbrush we use to start the day, the suit we wear, the fuel we use in our cars to drive to office, the car interiors, back home with cozy furniture, tapestry, and mattress of the bed we sleep on - all are petrochemicals i.e. chemicals from petroleum. Fig. 1.1 Petrochemicals in our Lives

Polyester Clothing

Nylon Can

PVC Pipes

Acrylic Carpet

Understanding Oil & Gas Business

2 Notes

Oil business has been responsible for prosperity, war, intrigues and adventure. Search of oil and gas leads us to some of the most exotic forests, deserts, and ocean. Perhaps some of the most beautiful man made sights in the world are offshore platform in deep ocean, array of offshore rigs in a remote desert or jungle or an illuminated petrochemical complex at night.

Fig. 1.2 Offshore Jackup Rig

Let us understand the importance of oil and gas industry by looking at its share in the energy supply to the world (Fig. 1.3). More than 60 % of the energy needed in the world is provided by oil and gas. Fig. 1.3 Distribution of Energy Supply

UNIT 1 Basic Concepts

And it is not really as expensive as it sounds (Fig. 1.4). Fig. 1.4 Price Comparison

To understand oil and gas business, one needs to understand a whole spectrum of activities from oil well to petrochemicals. It is also important to understand the trend and future of the industry in terms of technology, economics and pricing of energy resources. Energy price is very important for the economy of any country. As stated earlier, oil and gas provide over sixty percent of the energy requirement of the world. Oil had been the dominant component of the mix. Oil prices have been controlled from time to time to a high level by the petroleum exporting countries (OPEC). But one positive development is that now natural gas is overtaking oil. During the year 2000, the increase in the energy consumption of the world was 180 Million Tons of oil equivalent. Out of this, share of oil was 20%, share of gas was 55% and that of coal was 15%. Its is expected that gas will replace oil as dominant energy provider in near future. It is cleaner, cheaper and new discoveries and reserves of gas field are coming up in many parts of the world including India. Very often the question comes up how long the hydrocarbon resources (oil and gas) will last. Many predict oil and gas will start depleting in another 20 to 30 years.

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But the world is keeping on adding new hydrocarbon finds and developing technology to recover more hydrocarbons from existing oil and gas fields. Also major R&D work is going on to find how to exploit huge reserves of ‘Methane Hydrates’ i.e. an unstable compound of water and methane, lying untapped deep below the ocean in many parts of the world including coastal areas of India. It is a fact that although the oil and gas industry will continue to dominate for several decades from now, at some point of time other forms of energy will take over. Oil and gas industry generates wealth, and a part of the wealth is being put into R&D to innovate for the future. We shall cover the topic in a later section on future trends. Let us not call the industry just oil and gas industry - it is energy industry. Let us start on the path of understanding oil and gas business. The first step is to understand what is oil and what is gas, how it originated and what we get out of it. Unit 1 focuses on getting to understand the basics.

UNIT 1 Basic Concepts

What is Petroleum Petroleum is a word derived from the Latin words Petra (rock) and Oleum (oil). It essentially comprises of naturally occurring hydrocarbons i.e. compounds made of carbon and hydrogen atoms. These hydrocarbons are trapped below the surface of the earth, in porous rocks, in the form of oil and gas. From where did the hydrocarbons come? There are various theories. The most accepted theory is the organic theory: 6 Hydrocarbons came from remains of the bodies of prehistoric land based animals, marine organisms (plankton) and vegetation, which were washed away and buried below the earth during upheavals on the earth's surface millions of years ago. 6 In the course of time the buried organic matters decomposed and the carbon and hydrogen present in these reacted under heat and pressure to form various compounds, generally hydrocarbons. 6 The hydrocarbons got trapped in the porous rocks and were covered by hard sedimentary rocks that formed over it. They acted as “cap” or seal to prevent hydrocarbons from escaping. As explained later, carbon and hydrogen atoms can join together to form molecules of various sizes and structures. Hydrocarbons could be a small molecule with combination of one or a few carbon atoms with hydrogen (e.g. Methane CH4 , Ethane - C2H6). Or it could be very large molecule by combination of dozens of carbon and hydrogen atoms (e.g. Wax - C20H42) or even thousands of carbon and hydrogen atoms (e.g. Polythene). Petroleum is essentially composed of hydrocarbons with some other impurities. The words ‘petroleum’, ‘oil and gas’ and ‘hydrocarbon’ are all used synonymously in the oil and gas industry.

5 Activity 1a

What is the difference between crude oil and vegetable oil in terms of composition and properties?

Understanding Oil & Gas Business

6 Notes

Hydrocarbons in petroleum could be in gaseous, liquid or solid form depending on the type and size of hydrocarbon molecule: 6 It can be in gaseous form as natural gas, which can be

associated with oil in an oil field or found free of oil in a gas field. 6 It can be in liquid form as crude oil (dark and viscous), or

condensate (clear and volatile like motor gasoline). 6 The solid and semi-solid forms of petroleum are called

asphalt and tar. Petroleum as a general term is used for all three mentioned above. Table 1.1 Light and Heavy Hydrocarbon Molecules Name Methane Hexane Octane Wax

Formula CH4 C6 H14 C8 H18 C20 H42

Phase Gas Liquid Liquid Solid

Reservoir, Well and Well Fluid Through the burial and decomposition of organic material, huge amount of hydrocarbons are formed below the earth's surface. Movements and convulsions below the earth's surface resulted in different types of geological formations , where the hydrocarbons are trapped. In these formations, the hydrocarbons are contained by porous rocks known as source rock, covered with strata of hard sedimentary rocks known as cap rock which settled over them. When huge quantity of recoverable hydrocarbon is trapped in rock formations below the earth, it is called Reservoir. Fig. 1.5 depicts a typical formation of a reservoir. The surface on earth above the reservoir is called oilfield or gas field or condensate field depending on what it produces.

UNIT 1 Basic Concepts

Fig 1.5 Hydrocarbon Formation Well pipe

Earth Surface Sediments forming impervious layer called Cap Rock.

Water

Earth movements cause folds in earth crust. Gas Oil Hydrocarbons trapped by the Cap Rock, in the ‘pores’ of sedimentary rock act as a reservoir.

It must be noted that the reservoir in an oil field is not like a pool of liquid or a container filled with gas. It is oil or gas trapped in pores of porous sedimentary rocks, covered by impervious cap rock. To produce oil from the reservoir, wells are drilled through the surface of the earth. A well is then perforated at right location from where the oil or gas enters the well pipe and rushes out because of high pressure. Formation of reservoir structure is explained in greater detail in Unit - 3. What is Well Fluid? The fluid that comes out of the well in an oilfield or gas field is called well fluid. Well fluid is a mixture of crude oil, natural gas and saline water along with small amounts of sand and sludge. The water is called formation water or produced water. Points to Remember If the crude oil had been just made of hydrocarbons, processing to get the final products would have been easy and at low cost. But a number of undesirable components come out with the well fluid, which increases the processing blocks and processing cost.

7 Notes

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8 Activity 1 b

Is Helium a useful chemical? What are its uses?

6 Other components like sulfur compounds, carbon dioxide, nitrogen, traces of metals are also present. Their removal constitutes part of processing. 6 Proportion of oil, water and gas may vary widely from one field to other. It changes substantially with time during production. 6 Normally, well fluid comes out on its own pressure, which depletes with time. Artificial methods of recovery are used in later stages of production.

Crude Oil and Natural Gas The first processing step in an oilfield is separation between crude oil, natural gas and produced water. What is Crude Oil? Crude oil is a mixture of about 500 organic chemicals, predominantly hydrocarbons (molecules made of carbon and hydrogen). It is recovered from underground reservoirs, normally 1000 - 5000 meters down the earth. Crude oil can be of wide variety and characteristics. It could be very fluid, very viscous or semisolid. The colour could be black, dark brown, amber or light brown. It is also called Petroleum. What is Natural Gas? Natural gas is a mixture of the lightest hydrocarbons like methane, ethane, propane and butane. It also contains water to its saturation limit. It may also contain hydrogen sulphide (H2S), carbon dioxide (CO2), nitrogen (N2) and occasionally small amounts of helium (He). When natural gas comes out of the well along with crude oil, it is called associated gas. Associated gas is produced along with crude in a field which is essentially an oil producing field.

UNIT 1 Basic Concepts

When the well produces mainly gas with very little liquids, it is called free gas. Free gas production can be shut when we do not want it. When acid gases like CO2 and H2S are present in substantial quantity, the gas is called sour gas. Otherwise it is called sweet gas. Various Forms of Natural Gas There often exists a lack of understanding regarding the various terminologies or nomenclature used in the industry in describing components or forms of natural gas. The most commonly used ones are NGL, LPG, LNG, and CNG. Let us understand what are these and how they differ from natural gas. NGL: During production or transportation of gas, the heavy components such as pentane or hexane, condense due to natural cooling and separate out as liquids. This is called NGL (Natural Gas Liquids). As the name suggests, this is not really a gaseous component, but volatile liquid. LPG: The propane/ butane component of the natural gas is liquefied under moderate pressures and is supplied as cooking gas fuel. This is called LPG (Liquefied Petroleum Gas) LNG: Natural gas in bulk is liquefied under very low (cryogenic) temperature for transportation in large quantities by marine tankers. This is bulk of the natural gas in liquefied form and is re-vaporized after receiving it at its destination from tankers, to be used as natural gas. The objective of converting the gas to LNG is transportation in large quantities or export by marine tankers. This is called LNG (Liquefied Natural Gas).

9 Notes

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10 Notes

CNG: Natural gas is compressed to high pressures for use as automotive fuel or for transportation in small quantities. This is natural gas in highly compressed form but not liquefied. It is called CNG (Compressed Natural Gas).

Elementary Concepts on Hydrocarbons Now that we know crude oil is made of around 500 components, mainly hydrocarbons and natural gas is mainly light hydrocarbons, it becomes important to understand a little basic about hydrocarbon molecules. The whole petroleum and petrochemical industry revolves around 6 Starting with the hydrocarbon molecules as produced naturally from the well. 6 Rebuilding them into valuable products by various types of processing. What is Hydrocarbon? Hydrocarbons are compounds made of carbon and hydrogen. The hydrocarbon molecules are formed by6 Bonding of hydrogen atoms to carbon atoms. 6 Bonding of a number of carbon atoms to form chain or cycle or a combination of chain and cycle. 6 The number of carbon atoms bonded together can be a few or many, in various combinations, creating numerous chemicals. 6 The bonding of carbon atoms could be in the form of a straight chain, branched chain or cyclic manner.

UNIT 1 Basic Concepts

Typical hydrocarbon structures are depicted in Fig. 1.6.

Notes

Fig. 1.6 Hydrocarbon Structure Straight Chain Hydrocarbon

H H H H H H | | | | | | H - C- C- C- C- C- C - H | | | | | | H H H H H H

Cyclic Hydrocarbon

(C6H14) Toluene C 7H 8

The phase (solid, liquid or gas) of the hydrocarbon depends on the number of carbon atoms joined together in a chain e.g. CH4 (METHANE) C6H6 (BENZENE) C20 H42 (WAX)

: : :

11

GAS LIQUID SOLID

Crude oil is made of a mixture of more than 500 components, mainly Hydrocarbons, which are the desired components. Crude oil contains from light components as dissolved gases (LPG) , light liquids (Petrol, diesel) to heavy stock like wax, tar and resins. The more carbon atoms a hydrocarbon molecule has, 6 the "heavier" it is (the higher is its molecular weight). 6 and the higher is its boiling point.

Composition of Crude Oil Crude oil is predominantly made of hydrocarbons. It is composed of three main hydrocarbon groups: 6 Paraffins 6 Naphthenes 6 Aromatics It also contains unstable hydrocarbons called olefin. Paraffins are straight chain compounds, chemically stable. Lighter ones (CH4 , C2H6) are gas. Heavier molecules are liquid (oil) or solid (wax).

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12 Activity 1d

Write down structural formula of seven hydrocarbons made of six carbon atoms

Naphthenes consist of carbon rings, with/without side chains. Saturated with hydrogen, naphthenes are also chemically stable. Lighter naphthenes are liquids and heavier ones could be solid. Aromatics are compounds having a ring of six carbon atoms with alternating double and single bonds and six hydrogen atoms. They are relatively unstable. Olefins are double bonded hydrocarbon chains, normally produced during high temperature processing of petroleum. Olefins are unstable and polymerize easily i.e. a large number of olefins can combine together easily to form large gummy or plastic molecules. Fig. 1.7 Types of Hydrocarbons Olefins

Paraffins

Methane CH4

Ethane C 2H 6

Normal Butane nC4H10

Propane C 3H 8

Propylene C 3H6

Isobutane

Aromatics

Cyclohexane C6H12

Dimethyl Cyclopentane C7H14

Naphthenes

Benzene C 6H 6

Toluene C 7H 8

Xylene C8H10

UNIT 1 Basic Concepts

Some Important Concepts on Crude Oil Carbon Numbers The hydrocarbons are often referred in terms of number of carbon atoms rather than whole formula. Example: C1 = Methane C4 = Mixture of Butane and hydrocarbons with 4 carbon atoms C7 = Mixture of all hydrocarbons with 7 carbon atoms. For further clarity let us put down some of the paraffin hydrocarbons the symbol (-) indicating carbon to carbon bonds: Methane Ethane Propane Butane

CH4 C 2H 6 C 3H 8 C4H10

CH4 CH3 - CH3 CH3CH2CH3 CH3 - CH2 - CH2 - CH3 (normal butane or n-butane) Butane structure can also be branched chain type as given below: CH3 - CH - CH3 CH3 (Isobutane or i-butane)

Both the structures of butane have same number of carbon atoms and same number of hydrogen atoms i.e. C4H10. The only difference is how the carbon atoms are bonded with each other. This makes them different chemical entities but with very similar and close physical properties like boiling point and vapor pressure. The branched chain hydrocarbons of same carbon numbers, same number of hydrogen atoms and same chemical formula are called isomers.

13 Notes

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14 Notes

Now let us look at Pentane. Pentane

C5H12

CH3 - CH2 - CH2 - CH2 - CH3 (n-pentane)

Pentane can have quite a few isomers: CH3 - CH - CH2 - CH3 CH3

CH3 - CH - CH3 CH2 CH3

Thus one can have more and more isomers as the number of carbon atoms in the chain increases. In addition to the numerous isomers, there are other types of hydrocarbons like olefins (double bonded or triple bonded hydrocarbons). C5 and higher hydrocarbons can have cyclic structures (naphthenes and aromatics) and there could be molecules with combination of cyclic and straight chain hydrocarbons. For example C6 hydrocarbon can be compounds of 6 Normal paraffinic chain structure (e.g. normal hexane) 6 Isomers (iso-hexanes) 6 Olefinic structures or structures with double bond (hexenes) 6 Cyclic structure (benzene) Thus just saying C6 means a number of hydrocarbons with six carbon atoms put together in various forms. That explains: 6 How innumerable varieties of hydrocarbon molecules are possible. 6 How with same number of carbon atoms, say C8, numerous hydrocarbon compounds are possible. Higher the number of carbon atoms, more numerous is the possible hydrocarbon compounds.

UNIT 1 Basic Concepts

Classification of Crude Oil

15 Activity 1e

Various crude oils are often referred by their API Gravity. API Gravity is expressed as (141.5/ Sp. Gravity - 131.5). As specific gravity is in the denominator, API Gravity is higher for lighter crude and lower for heavier crude. A comparative idea of this gravity unit can be obtained by comparison with water: Water:

10 API

Typical API Gravity figures for crude oil are Mumbai High Crude : Arabian Crude : Venezuelan Crude :

40 API - Light Crude 34 API - Medium Crude 15 API - Heavy Crude

There could be sub-categorization as Medium Heavy or Light Medium. Another common classification is based on Characterization Factor, which depends on API Gravity and Boiling Point. The crude oils are also classified in terms of chemical nature e.g. 6 Paraffinic base 6 Asphaltic base 6 Intermediate base 6 Naphthenic base Crude oils for which the residue after distillation contains paraffin wax is called paraffinic. If the residue contains asphalt, it is called asphaltic base and so on. Refinery processing scheme and product yields depend on type of crude in terms of chemical nature and gravity. It also indicates the type of product it can yield.

Calculate API Gravity of crude oils with specific gravity of 0.8, 0.9 and 0.95

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16 Notes

As typical example: 6 Paraffinic base crude do not yield good bitumen (road tar) and is not good for lubricating oil manufacture. But it is good for diesel. 6 Light crude contains more of gasoline. 6 Medium crude is good for diesel production. 6 Heavy crude may give better bitumen. 6 Naphthenic crudes are good for lubricating oil. Cut or Fraction Crude Oil and its products are mixtures of several components. Each component has a boiling point. It is interesting to examine what would be the boiling point of mixture of several liquids. Q - What is the boiling point of a mixture of two liquids A and B mixed 50-50, A and B having a boiling points of 70oC and o 80 C respectively? Q - What is the boiling point of a mixture of four liquids in equal parts having boiling points of 100,200,300 and o 400 C? None of the above mixtures will have a single boiling point. If you start boiling such a mixture, it will start boiling close to the boiling point of the lightest component. The lightest component will start vaporizing faster and as it gets removed (along with some of heavier components), the boiling temperature will keep rising. Towards end the last bits of the heaviest component will be left behind and will boil at close to its boiling point. Thus mixtures do not have a single boiling point, it has a boiling range - from the initial boiling point to the final boiling point.

UNIT 1 Basic Concepts

Liquid mixtures are identified with their boiling range. Crude oil being a mixture, has a boiling range. Each product like gasoline or kerosene are also mixtures and have a boiling range. Cuts, Fractions and Carbon Numbers Crude oil is a mixture of over 500 components. It has a boiling range of around 40-600oC. Each product from Crude oil is also mixture of several components (hydrocarbons). The hydrocarbons range from C1 to C65 in terms of carbon numbers. Product of a particular boiling range taken out of crude is defined as cut or fractions. The products are identified as cuts from crude of certain boiling ranges and carbon numbers. Table 1.2 Petroleum Product Cuts and Carbon Numbers Product / Cut Natural Gas Gasoline Kerosene Diesel (Gas Oil) Jet Fuel (ATF) Lube Oil Bitumen/Tar

Boiling Range <20 oC 40 - 200 oC 180 - 250 oC 240 - 350 oC o 170 - 240 C o 350 - 450 C 450 oC+

Carbon Number C1- C4 C5 - C10 C10 - C15 C14 - C20 C10 - C15 C20 - C30 C30 ++

Petroleum Products Crude oil (Oil) and natural gas (Gas) mixed along with water, comes out of the well as well fluid. Crude oil and natural gas together can be broadly referred as petroleum. Petroleum is just a raw material. Let us see what products we get from oil and gas that comes out from well head.

17 Notes

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18 Notes

Well Head to Energy and Petrochemicals There are two distinct uses of well head oil and natural gas as fuel and as high value products. Primary use of the petroleum products in the early days of its exploration has been as fuel. But later with the development of petrochemical area (plastics, fibers etc.), emphasis has shifted to greater valorization of the raw material. Let us look at the table below to understand this. Table 1.3 Petroleum as Fuel and as Value Products Fuel and Products

Calorific Value (Kcal/Kg)

Coal Crude Oil Fuel Oil Motor Gasoline Polythene Polystyrene

6,500 10,400 10,000 11,000 Not fuel Not fuel

Price US Dollars/Ton

80 150 120 180 500 550

The high calorific value of the petroleum products, its low cost in the past and its suitability for use as relatively clean fuel created incentive to consume as fuel. But in the current economic scenario, valorization to higher value products has become integral part of oil and gas industry. It is important to note that besides producing fuel and automotive products like gasoline or diesel, both crude oil and natural gas provide feed stock for petrochemicals. Feed stocks are component of crude oil and natural gas that are converted into high value petrochemical products like polythene, polyester, synthetic rubber and synthetic fiber etc. It is apparent from the table above, there is substantial valorization once the oil or gas is converted to petrochemicals. The macro-system from well head to Petrochemicals has been dealt in detail in the next section. For an initial understanding of the petroleum products let us have a look at the simple block diagram given in Fig. 1.8.

UNIT 1 Basic Concepts

19 Activity 1f

Fig. 1.8 Petroleum Utilization Blocks Oil Reservoir

Oil field Processing

Transportation Gas Oil

Gas Naphtha

Gas Processing

Petrochemical Feed stock (Ethane / Propane) Gas

Refinery Petrochemical Complex Power Generation

Refinery Products Petrochemical Product

Power

The various blocks in overall system are: 6 Well fluid is processed at the oilfield first. Oil and gas are separated, made transportable and despatched to the Refinery and Gas Processing Facility respectively. 6 Refinery produces products like petrol, diesel oil, lubricating oil etc. It also produces feed stock (Naphtha) for petrochemical (plastic, fiber etc.) manufacture. 6 Gas Processing Facility purifies the gas from undesirable components and separates feedstock for petrochemical production. 6 Petrochemical feed stocks from Gas Processing or Refinery or both are sent to a Petrochemical Complex for production of petrochemical. 6 The balance gas is used as fuel for power generation or as industrial fuel. Each individual block in the above diagram could be a separate company. And each of these blocks could be located far away from each other in the same or different countries. This makes the oil and gas industry a real global industry.

Name five items of daily use made from petrochemical source and name the petrochemical e.g. Toothbrush is made from nylon.

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20 Notes

Some important terms often used in oil and gas industry with respect to the block diagram Offshore : Oil or gas field situated in the sea / ocean. Onshore : Land based oil or gas field. Upstream :The blocks covering reservoir, production, processing and transportation of oil and gas is referred as upstream blocks. Downstream:Gas Processing, Refinery and Petrochemical Facilities are referred as downstream blocks. Products from Natural gas The natural gas is made mainly of the four lightest hydrocarbons i.e C1 (Methane), C2 (Ethane), C3 (Propane) and C4 (Butane). As gas separates out of the crude oil, it pulls out a little bit of heavier hydrocarbons like C5, C6 etc. Table 1.4 shows the typical composition of gas and use of various components towards high value product. Table 1.4 Gas Composition and Utilization Component Methane (C1) Ethane (C2) Propane (C3) Butane

(C4)

Heavies (C5+) (NGL) Hydrogen Sulfide (H2S) Carbon Dioxide (CO2) Nitrogen Water Total

Composition Utilization Volume % 50-96 Fuel, Petrochemical feedstock, power generation 2-15 Petrochemical feedstock 1-12 Petrochemical feedstock, LPG 0.5-3 Petrochemical feedstock, LPG 0.1-1 Refinery blending stock, petrochemical feedstock 0-15 Toxic, corrosive and undesirable component 0-30 No fuel value, corrosive, undesirable component 0-30 No fuel value, corrosive, undesirable component Saturated Undesirable component 100

UNIT 1 Basic Concepts

The points to note here are that:

21 Notes

6 There is a wide range of gas composition, varying from field to field and well to well. 6 Only consistent trend is the reducing pattern of the hydrocarbon constituents from the lightest to the heavier ones e.g methane followed by ethane and heavier hydrocarbons. 6 Utilization of gas as fuel is the easiest but lowest in the value chain. 6 Utilization of gas to make petrochemicals is the highest in the value chain. Hence very often the components of the gas are separated by gas processing to be used for manufacture of petrochemicals. While Table 1.4 gives a range for gas composition, typical gas composition are given in Table 1.5. Table 1.5 Typical Gas Composition Component (Volume%) Methane (C1)

Methane rich Associated gas Sweet Gas (mildly sour)

Sour gas Gas with high N2

94.5

76.5

71.5

62.5

(C2)

2.8

12.2

10.2

4.2

Propane (C3)

1.0

6.5

5.7

2.5

Butane

0.2

1.8

1.0

0.5

Ethane

(C4)

Heavies (C5+) (NGL)

Traces

1.0

0.5

0.1

Nil

3.5

Nil

2.0

7.6

5.4

Nil

24.8

Saturated

Saturated

100.0

100.0

Hydrogen Sulfide(H2S)

Nil

Carbon Dioxide

1.5

Nitrogen

Nil

300 ppm

Water

Saturated

Saturated

Total

100.0

100.0

Obviously each of these gases will have different processing techniques and problems in the Gas Processing Plant. These will be dealt with later. But let us look at the obvious 6 The methane rich gas will have very little feedstock for petrochemicals. 6 The associated gas is rich in petrochemical feedstock and LPG. 6 The sour gas will need treatment to remove highly toxic and corrosive Hydrogen Sulfide. 6 The nitrogen rich gas will have low calorific value.

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22 Notes

Products from Crude Oil The five hundred odd components mostly hydrocarbon ranging from C1 to C65 gives wider range of products. Each of the product by itself is a composite of numerous hydrocarbons. The crude oil is processed in the refinery to separate the base stock (raw products) by distillation into 'cuts'. Then the various product base stocks are processed and treated to meet specifications. Table 1.6 Products from Crude Oil Refining Product

Use

LPG

Domestic fuel, Petrochemical feedstock Petrochemical feedstock

Boiling range, composition

Motor gasoline

Automotive fuel

Octane number

Kerosene

Domestic fuel, lighting

Smoke point

Aviation Turbine Fuel

Aero plane fuel

Freezing point

Diesel oil

Automotive fuel

Cetane number

Fuel oil

Industrial fuel

Viscosity

Lubricating oil

Industrial lubricants

Viscosity

Bitumen (asphalt)

Road tar

Penetration Index

Paraffin Wax

Medicine, cosmetics

Pharmaceutical specs.

Naphtha

Key Specifications Vapor Pressure

The important petroleum products produced in bulk in a refinery are presented in Table 1.6. Each of the products has to meet certain performance specifications. Only one typical specification is stated in the table for a preliminary understanding of its significance with respect to the usage. It must be remembered that besides performance specifications, there are strict specifications to meet environment and emission norms. These are related to polluting components like sulfur, aromatics etc.

UNIT 1 Basic Concepts

Petrochemical Products / Petrochemicals What are petrochemicals? Petrochemicals are usually plastic products and chemicals that are derived from petroleum and natural gas and are made on a large scale (approximately >10,000 tons per annum upwards). As indicated in the earlier sections, certain components from gas processing plants and refinery are used as feedstock for manufacture of petrochemicals (e.g ethane, propane, naphtha). Petroleum products from refinery and natural gas, supply over 50% of the feedstock for the entire chemical industry and more than 50% of organic chemicals. As you can see in the next table, petrochemical products have permeated into every facet of our lives. A vast majority of them are polymers, whose molecules are tailored by reaction process to suit specific characteristics or properties. Table 1.7 Petrochemicals Types

Bulk Petrochemicals

Plastics

Polythene Polypropylene Polystyrene PVC Polycarbonate

Fibers

Polyesters Polypropylene Nylon Polyurethane Cellulose Polyacrylonitrile

Use Bags, laminates, boxes, shoes, fibers, toys, electronic goods, engineering items, numerous items of daily use

Fabric, clothing, bags, ropes, carpets, and numerousother irtems

Units Specifically Used in Oil and Gas Industry Oil industry uses certain specific units for production rates and volumes which will be bused frequently in our text. Due to past history of oil and gas industry which is predominantly the history of exploitation of hydrocarbon resources by the companies of American origin, the American units are more often used in the industry rather than Metric Units. Here are some important units commonly used with which one must get familiar.

23 Activity 1a

Understanding Oil & Gas Business

24 Notes

6 Crude-oil volume is usually measured in barrels. 6 One barrel holds 42 gallons (159 liters). 6 Weight or mass of crude in India is in metric tons (tonne). 6 A barrel of average crude oil weighs 0.150 ton, as a thumb rule. It must be remembered that it depends on the density of the crude oil. 6 Million Barrels of Oil Equivalent (MBOE) means amount of gas or any other fuel whose calorific value or heating value is equivalent of one million barrels of crude oil. 6 Oil production capacity or refinery capacity are often expressed in Barrels Per Day (BPD) or Barrels Per Standard Day (BPSD). Roughly 20,000 BPSD is equivalent to 1 Million Tons per year of crude, taking an average density of crude. [Note: It obviously will depend on density of crude oil.] 6 Some typical conversion figures used in the oil industry are given in Table 1.8. Table 1.8 Commonly Used Measurement Units in Petroleum Industry Unit Weight or Volume 1 Metric Ton (Tonne) 1 Barrel (Bbl)

1 Cubic Meter (CuM) 1 Million Tonne of Crude

1 Billion CuM of natural gas 1 Million Tonne of LNG 1 Million Tons Per Year of crude

Conversion Factor = 7.33 Barrels = 1.165 Cubic Meters = 0.136 Tonnes = 0.159 Cubic metres = 1 Kilo Liter (KL) = 0.858 Tonnes = 6.289 Barrels = 1.111 Billion CuM of Natural Gas = 39.2 Billion Cubic Feet Natural Gas = 0.805 Million Tonnes LNG = 0.90 Million Tonnes Crude Oil = 0.73 Million Tonnes LNG = 1.38 Billion CuM of Natural Gas = 1.23 Million Tonnes Crude Oil = 20,000 Barrels per standard day of crude

UNIT 1 Basic Concepts

Summary

25 Notes

In this section we talked about the origin of petroleum (oil and natural gas) and its composition. Oil and gas are made mainly of hydrocarbons that originated from decomposed organic material buried under earth's surface. Elementary chemistry was touched upon to clearly define what is hydrocarbon. We defined the various forms in which gas is used like LPG, LNG, NGL or CNG. Also the various products from oil and gas were identified. Petrochemical products were defined and how oil and gas provides the feedstock for manufacturing valuable petrochemical products was explained. We learnt the definition and concepts regarding: Reservoir Well Fluid Associated Gas NGL Boiling Range Offshore

Reservoir Rock Crude Oil Free Gas LNG Cuts Onshore

Cap Rock Natural Gas Sweet Gas LPG Fractions Platform

Trap Produced Water Sour Gas CNG FPSO

Besides common terminologies, commonly used units for measurement of weight and volume of petroleum was explained.

Questions Since this section explains elementary concepts about crude oil and defines certain basic terminologies used in the industry, an objective type questionnaire or quiz is the best way to judge the competence attained by the participants.

Objective type questions Please circle the correct answer or answers. Each question has one or more correct answers.

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26 Notes

No.

Question

Answer

1

Total number of chemical components in crude oil is-

2

The predominant components in crude oil are known as

3

Reservoir or hydrocarbon deposits below the earth surface are found as huge lakes or sea of oil. LPG is made of

(a) (b) (c) (a) (b) (c) (a) (b) (c) (a) (b) (c) (a) (b) (c) (a) (b) (c) (a) (b) (c) (a)

4

5

The largest constituent of natural gas is

6

FPSO is preferred for use in

7

Octane number of petrol used in cars in India is

8

FPSO stands for

(b) (c) 9

Arrange the following in decreasing density i.e from heaviest downwards.

10

Oil and gas are contained in

11

5 Million Tons per year of crude means

(a) (b) (c) (a) (b) (a) (b) (c)

12

Which of the following is used as feedstock to make Petrochemicals

13

Which of these items can not be made from Petrochemicals

14

Crude oil price during the current year has been in the range -

15

Conversion of Gas to LNG is made for

16

Which are the products from a Petroleum Refinery

17

To transport gas from Qatar to Japan, use is made of

(a) (b) (c) (d) (e) (a) (b) (c) (d) (a) (b) (c) (d) (a) (b) (c) (a) (b) (c) (d) (e) (f) (a) (b) (c)

100 500 250 Paraffin Aromatics Hydrocarbon True False Partly true Propane and Ethane Propane and Butane Butane LPG Ethane Methane Marshy lands Shallow waters Deep waters Above 100 Between 85 and 95 Below 85 Floating Process System Offshore Floating Production and Storage Offshore Floating Production & Storage Offloading LPG CNG NGL Reservoir Rock Cap Rock 20,000 Barrels per day 100,000 Barrels per day 75,000 Barrels per day Naphtha Kerosene LPG Ethane All of above Insulating Material for furnaces Optical Lens Pressure Vessels Gas Turbine blades 15 to 35 US$/Barrel 22 to 35 US$/Barrel 15 to 25 US$/Barrel 15 to 22 US$/Barrel Making Petrochemical Transportation of Gas To generate power Motor Gasoline Ethylene Naphtha Propylene Lube Oil Polypropylene Transcontinental pipeline Marine Tankers CNG

UNIT 1 Basic Concepts

18

Naphthenes are

(a) (b) (c) (d)

19

MTOE means

(a) (b) (c)

20

The most predominant component of natural gas is

21

Which of the following gases is heavier than air

22

LPG contains mainly

23

Which of the following is heavier

(a) (b) (c) (d) (a) (b) (c) (a) (b) (a) (b)

24

LPG is used as domestic fuel because

(a) (b) (c)

25

Which is the heaviest crude of the three

(a) (b) (c)

Hydrocarbons Straight Chain Hydrocarbons Non-hydrocarbons Hydrocarbons with cyclic structure Million Tons of Oil Export Metric Tons of Oil Equivalent Million Tons of Oil Equivalent Methane Ethane Propane Butane Nitrogen Ethane Butane Methane Butane 1 cubic Meter of gas at 2 bar and 30 deg C 0.2 cubic Meter of same gas at 20 bar and 30 deg. C It is liquid at atmospheric pressure It is gas at ow l pressure It is liquid at moderate pressure 45 API 35 API 37 API

27 Notes