petroleum industry.pdf
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Course: Chemical Technology (Organic) Module VI
Lecture 1
Introduction: Status ofPetroleum Refinery, Crude Oil
And Natural Gas Origin,
Occurrence, Exploration,
Drilling And Processing, Fuel
Norms
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LECTURE 1
INTRODUCTION
Petroleum and derivatives such as asphalt have been known and used for almost 6000 years and
there is evidence of use of asphalt in building more than 600 years ago. Modern petroleum
refining began in 1859 with discovery of petroleum in Pennsylvania and subsequent
commercialization. The exploration of petroleum originated in the latter part of the nineteenth
century [Speight, 1999].
CRUDE OIL AND NATURAL GAS ORIGIN, OCCURRENCE,EXPLORATION AND DRILLING
Oil and natural gas were formed hundred years ago from the prehistoric plant and animals. it is
believed that hydrocarbon formed by the thermal maturation of organic matter buried deep in
earth. over the millions of years under extreme pressure and high temperature these organic
matter converted to hydrocarbons consisting of oil and gas. Hydrocarbons are present in the
variety of forms: koregen, asphalt, crude oil, natural gas, condensates, and coal in solid form.
Oil and gas production includes exploration, drilling, extraction, stabilization. The underground
traps of oil and gas are called reservoir. Various types of traps are structural traps, stratigraphic
traps and combination traps Most reservoir contain water also along with oil and gas. Reserves
are classified as proven, probable and possible reserves. Earlier finding of oil and gas was matter
of luck and hit and miss process. Tools used for oil and gas exploration are based and dependent
on gravity change, magnetic field change, time, change and electrical resistance. However it has
become now more challenging and complex. With advent of three dimensional seismic
technology which is based on the sound waves, identify the subsurface formation by reflection of
sound, there has been much improvement in identification of oil and gas traps and reservoirs.
Seismic technology significantly improves the method of estimating the oil and gas deposits.
Next step after exploration is the drilling of exploratory well. Drilling may be vertical drilling or
horizontal drilling. Drilling may be performed on-shore or off-shore. Horizontal drilling and
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hydro-fracturing has resulted in economical and more productive drilling of shale gas which was
not economical with conventional vertical drilling.
COMPOSITION OF PETROLEUM (CRUDE OIL)Petroleum (Crude oil) consists of mainly carbon (83-87%) and hydrogen (12-14%) having
complex hydrocarbon mixture like paraffins, naphthenes, aromatic hydrocarbons, gaseous
hydrocarbons (from CH4 to C4H10) [Mukhulyonov et al., 1964]. Table M-VI 1.1 gives more
details about composition of petroleum. Besides crude oil also contains small amount of non
hydrocarbons (sulphur compounds, nitrogen compounds, oxygen compounds) and minerals
heavier crudes contains higher sulphur. Depending on predominance of hydrocarbons, petroleum
is classified as paraffin base, intermediate base or naphthenic base.
Table M-VI 1.1: Composition of Petroleum
Hydrocarbons
Hydrogen
Family
Distinguishing
characteristics
Major
hydrocarbonsRemarks
Paraffins
(Alkanes)
Straight carbon
chain
Methane, ethane,
propane, butane,
pentane, hexane
General formula CnH2n+2
Boiling point increases as the
number of carbon atom increases.
With number of carbon 25-40,
paraffin becomes waxy.Isoparaffins
(Iso alkanes)
Branched
carbon chain
Isobutane,
Isopentane,
Neopentane,
Isooctane
The number of possible isomers
increases as in geometric
progression as the number of carbon
atoms increases.
Olefins
(Alkenes)
One pair of
carbon atoms
Ethylene,
Propylene
General formula CnH2n
Olefins are not present in crude oil,
but are formed during process.
Undesirable in the finished product
because of their high reactivity. Low
molecular weight olefins have good
antiknock properties.
Naphthenes 5 or 6 carbon
atoms in ring
Cyclopentane,
Methyl
cyclopentane,Dimethyl
cyclopentane,
General formula CnH2n+2-2R n
R N is number of naphthenic ring
The average crude oil contains about
50% by weight naphthenes.
Naphthenes are modestly good
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cyclohexane,1,2 dimethyl
cyclohexane.
components of gasoline.
Aromatics 6 carbon atom
in ring with
three aroundlinkage.
Benzene,
Toluene, Xylene,
Ethyl Benzene,Cumene,
Naphthaline
Aromatics are not desirable in
kerosene and lubricating oil.
Benzene is carcinogenic and henceundesirable part of gasoline.
Non Hydrocarbons
Non-hydrocarbons Compounds Remarks
Sulphur compounds Hydrogen sulphide,
Mercaptans
Undesirable due to foul odour
0.5% to 7%
Nitrogen compounds Quinotine, Pyradine,
pyrrole, indole, carbazole
The presence of nitrogen
compounds in gasoline and
kerosene degrades the colour of
product on exposure to sunlight.
They may cause gum formation
normally less than 0.2.
Oxygen compounds Naphthenic acids, phenols Content traces to 2%. These
acids cause corrosion problem at
various stages of processing and
pollution problem.
Source: Mall,2007
PROCESSING OF PETROLEUM (CRUDE OIL)
Processing of Petroleum from drilling: when petroleum is drilled and brought to the surface, the
pressure drops resulting in separation of gases from the crude oil. Further processing of crude
involves separation of water and oil and salt. Associated natural gas is further processed for
separation of natural gas, condensate, acid gases. Crude oil varies in appearance from brownish
green mobile liquid to black viscous and sometimes semisolid. . Figure M-VI 1.1 illustrates the
process of oil and gas processing [Ravindranath and Habibula, 1992]
.
CRUDE OIL PROCESSED IN INDIA
Both indigenous and imported crude oil are processed in India. Various imported sources of
crude oil is given in Table M-VI 1.2.There has been continuous changes in the crude oil quality.
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179
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Table M-VI 1.2: Imported Crude Sources
Middle East
Kuwait, Dubai, S. Arabia( Arab Mix, Arab medium), Iraq,
Abu Dhabi, UAE(upper Zakum,Murban,UM Shaif)
Iran, Kuwait : Ratawai, Egypt( Suez Mix, Zeit mix),
Mediterranean Libya - Es Sider
West Africa Nigeria-Bonny Light, Eseravos, Forcados, Penington,Quaiboe)Angola, -Cabinda, Palanca, Girassol
Eq. Guinea -Ceiba, Zaffiro
Congo -Nikossa, Kitina
Far East Malaysia -Labuan, Miri Light
Australia -Barrow Island, Cooper Basin,Chalis
Brunei -Seria Light
Table M-VI 1.3: Worldwide Crude quality
Properties 1985 1990 1995 1999 2010
Sulphur,Wt % 1.14 1.12 1.31 1.41 1.51
API gravity 32.7 32.6 32.4 32.2 31.8
Residue in crude
,vol %
19 19.4 19.8 20.2 21.3
‘S’ in residue ,Wt%
3.07 3.26 3.61 3.91 4.0
Metals in residue,
ppm
275 286 297 309 320
Source: Samanti,R.K . “Refining challenges and Trends” 6th summer School on “Petroleum
refining and petrochemicals” June 6, 2012, Organised by New Delhi
Table M-VI 1.4: Characteristics of Various Crude Oil
Sources of indigenouscrude
Salient features
Assam Crude Nahorkatia/
Moran
31 o
API, Sulphur 0.3%, Pour point +30oC, High
aromatics, Total distillate yield 65%.
ONGC, Lawkwa,
Rudrasagar
27o
API, Sulphur 0.3%, High aromatics, Distillate yield
57%.
Ankleshwar Crude 48oAPI, Sulphur 0.1%, Pour point +18
oC, Distillate
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yield 80-82% (Light distillates 24%, Middle distillate
47%), Wax content 9.9%, total sulphur 0.02%.
North Gujarat Crude 28oAPI, Sulphur content 0.1%, Pour point +27
0C,
Distillate yield low 33-35%, High organic acidity.
Bombay High Crude 38oAPI, Sulphur 0.2%, Pour point +30
oC, Distillate
yield 65-70% (Light distillate 24%, Middle distillates
46%), High aromatics.
Narimanam Crude 46oAPI, Sulphur 0.1%, Pour point 3
oC, Distillate yield
80%.
KG Basin Ravva Crude 36oAPI, Sulphur 0.1%, Pour point +30
oC, Distillate
yield 61%.
Source: Mishra & Unnikrishnan, 1996, p.22
REFINERY PROCESSESRefining of crude oils or petroleum essentially consists of primary separation processes and
secondary conversion processes. The petroleum refining process is the separation of the different
hydrocarbons present in the crude oil into useful fractions and the conversion of some of the
hydrocarbons into products having higher quality performance. Atmospheric and vacuum
distillation of crude oils is the main primary separation processes producing various straight run
products, e.g., gasoline to lube oils/vacuum gas oils (VGO). These products, particularly the light
and middle distillates, i.e., gasoline, kerosene and diesel are more in demand than their direct
availability from crude oils, all over the world. The typical refinery operation involves separation
processes, conversion processes, finishing processes, environmental protection processes.
Typical refinery process diagram is shown in Figure M-VI 1.2.
SEPARATION PROCESSES Distillation
Absorption
Extraction Crystallisation
Adsorption
PRIMARY DISTILATION (Atmospheric Distillation) Refinery gases Liquefied petroleum gases
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Gasolines or naphtha (light/heavy) Kerosene, lamp oil jet fuel Diesel oil and domestic heating oils
Heavy Industrial fuels
SECONDARY DISLLATION (Vacuum Distillation) Light Distillate
Middle distillate Heavy distillate Asphalt/bitumen
CONVERSION PROCESSES
Process for Improvement of Properties Catalytic reforming Isomerisation
Alkylation
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Figure M-VI 1.2: Typical Refinery Processes and Products
Thermal processes:
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Visbreaking Coking
Catalytic Processes Catalytic cracking(FCC)
Hydrocracking Steam reforming Hydroconversion
FINISHING PROCESSES Hydrotreatment/hydrogenation Sweetening
ENVIRONMENTAL PROTECTION PROCESSES Acid gas processing
Stack gas processing
Waste water treatment process
TYPES OF PETROLEUM REFINING PROCESSESPRIMARY PROCESSES: Separating crude into its various fractions e.g. CDU/VDU
SECONDARY PROCESSES: Processing residues from primary processes and upgrading them
to distillates e.g. FCCU, HCU
RESIDUE UPGRADATION PROCESSES: Bottom of the barrel upgradation eg. RFCCU,
DCU, DCC
FINISHING/ PRODUCT QUALITY IMPROVEMENT PROCESSES: Processes to improve
product quality and meet stringent product quality specifications eg. DHDS, DHDT, CRU
REFINING CAPACITYGlobal oil consumption and refining capacity, World Refining Capacity Country wise 2009 are
given in Table M-VI 1.5 and Figure M-VI 1.3. Present refining capacity in India is million tones
per annum. The present import of crude in India is around 180 million tones per annum. It is
expected that the import of crude oil has to exceed 240 million tones per annum in the next five
years, if GDP growth of around 6 to 7percent were to be sustained [Venkat, 2012].
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Changing Scenario in Gasoline and Diesel Specifications
Major Parameters of Gasoline Specifications [Table M-VI 1.6]
• Lead phase out
• Lower RVP•
Lower benzene & aromatics
• Lower olefin content
• Limited Oxygen content• Lower Sulfur content
Major Parameters of Diesel Specifications [Table M-VI 1.7]
• Low sulfur
• Low aromatics
• High cetane number
• Lower density
• Lower distillation end point
Table M-VI 1.6: Key Specification of Gasoline
Specification BIS
2000
BS-II Euro-III Eqv. Euro-IV Eqv .
Regular Premium Regular Premium
Sulphur,ppmw(max)
1000 500 150 150 50 50
RON,Min 88 88 91 95 91 95
MON,Min No
spec.
No
spec.
81 85 81 85
AKI,Min 84 84 81 85Benzenevol%(max)
5 3 1 1 1 1
Aromaticsvol%(max)
Nospec.
Nospec.
42 42 42 35
Olefinsvol%(max)
Nospec.
Nospec.
21 18 21 81
Source: Rajgopal, S. “Refining challenges and Trends.6th
summer School on “Petroleum refining
and petrochemicals” June 6,2012, Organised by New Delhi
Table M-VI 1.7: Key Specification of High Speed Diesel (HSD)
Specification BIS2000 BS-II Euro-III
Equ.
Euro III
Equiv.
Density@15oC
Kg/m3
820-860 820-860 820-845 820-845
Sulphur content ppmw(max)
2500 500 350 50
Cetane 48 48 51 51
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number(min)
Distillation
99% Vol (oC
max)
370 370 360 360
Polycyclic
aromaticshydrocarbons
(PAH),%
massmax
No spec. No spec 11 11
Source: Rajgopal, S. “Refining challenges and Trends.6th
summer School on “Petroleum refining
and petrochemicals” June 6,2012, Organised by New Delhi
MAXIMIZING VALUE ADDITION TO REFINERY STREAMSFor a refinery to be successful today, it has to be integrated with petrochemical to benefit from
better realization from value added products and to mitigate the effect of volatile oil process and
highly competitive refining business [Singh and Vaidya, 2012]. Some of the streams which can
maximize value addition to the refinery is given in Table M-VI 1.8.
Table M-VI 1.8: Maximizing Value Addition to Refinery StreamsStreams Utilization
Fuel Gas H2
FCC
Ethylene Ethyl Benzene to Styrene
Propylene Cumene, Iso-Propanol
Butylene Methyl Ethyl Keton, MTBE,
Xylenes
C3 Propylene + H2
C4 Discussed Separately
LPG BTX
C5 TAME
Light naphtha LPG, BTX
Heavy Naphtha Aromatics
Kerosene n-paraffins to LABLCO (FCC unit) Mixed Naphthalenes
Coker Kerosene α-Olefins
Sources: M. O. Garg Director Indian Institute of Petroleum, Dehradun 23 rd National Convention of
Chemical Engineers IIT Roorkee, 5 – 7 October 2007
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