Course: Chemical Technology (Organic)
Module VI
Lecture 1
Introduction: Status of
Petroleum Refinery, Crude Oil
And Natural Gas Origin,
Occurrence, Exploration,
Drilling And Processing, Fuel
Norms
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
EXPLORATION AND DRILLING
GAS
ORIGIN,
OCCURRENCE,
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
176 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
Distinguishing
Major
Hydrogen
Remarks
Family
characteristics
hydrocarbons
Paraffins
Straight carbon Methane, ethane, General formula CnH2n+2
(Alkanes)
chain
propane, butane, Boiling point increases as the
pentane, hexane
number of carbon atom increases.
With number of carbon 25-40,
paraffin becomes waxy.
Isoparaffins
Branched
Isobutane,
The number of possible isomers
(Iso alkanes)
carbon chain
Isopentane,
increases
as
in
geometric
Neopentane,
progression as the number of carbon
Isooctane
atoms increases.
Olefins
One pair of Ethylene,
General formula CnH2n
(Alkenes)
carbon atoms
Propylene
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 Cyclopentane,
General formula CnH2n+2-2Rn
Methyl
atoms in ring
RN is number of naphthenic ring
cyclopentane,
The average crude oil contains about
Dimethyl
50% by weight naphthenes.
cyclopentane,
Naphthenes are modestly good
177 Aromatics
cyclohexane,
1,2 dimethyl
cyclohexane.
6 carbon atom Benzene,
in ring with Toluene, Xylene,
three around Ethyl Benzene,
linkage.
Cumene,
Naphthaline
Non Hydrocarbons
Non-hydrocarbons
Sulphur compounds
Nitrogen compounds
Oxygen compounds
Compounds
Hydrogen sulphide,
Mercaptans
Quinotine,
Pyradine,
pyrrole, indole, carbazole
Naphthenic acids, phenols
components of gasoline.
Aromatics are not desirable in
kerosene and lubricating oil.
Benzene is carcinogenic and hence
undesirable part of gasoline.
Remarks
Undesirable due to foul odour
0.5% to 7%
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.
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.
178 Now imp
ported crudee oils are beeing heavierr with higheer sulphur coontent. Channging worlddwide
crude oiil scenario is given in
n Table M-VI 1.3. Inddigenous crrude oil is also varyinng in
characterristics. Rajassthan crude oil contain
ns high sulphhur and maay pose seriious challenge to
Indian petroleum refining indusstry Typicall characterisstics of variious indigennous crude oil is
given in Table M-VI 1.4.
Figure M-VI
M
1.1: Oil and G
Gas Processsing
Sou
urce: Ravindraanath and Haabibula, 1992
179 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),
Libya - Es Sider
Nigeria-Bonny Light, Eseravos, Forcados, Penington,
Quaiboe)
Angola,
-Cabinda, Palanca, Girassol
Eq. Guinea
-Ceiba, Zaffiro
Congo
-Nikossa, Kitina
Malaysia
-Labuan, Miri Light
Australia
-Barrow Island, Cooper Basin,Chalis
Brunei
-Seria Light
Mediterranean
West Africa
Far East
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 indigenous
crude
Assam Crude Nahorkatia/
Moran
ONGC,
Lawkwa,
Rudrasagar
Ankleshwar Crude
Salient features
31 oAPI, Sulphur 0.3%, Pour point +30 oC, High
aromatics, Total distillate yield 65%.
27 o API, Sulphur 0.3%, High aromatics, Distillate yield
57%.
48 oAPI, Sulphur 0.1%, Pour point +18 oC, Distillate
180 yield 80-82% (Light distillates 24%, Middle distillate
47%), Wax content 9.9%, total sulphur 0.02%.
28 oAPI, Sulphur content 0.1%, Pour point +27 0C,
North Gujarat Crude
Distillate yield low 33-35%, High organic acidity.
38 oAPI, Sulphur 0.2%, Pour point +30 oC, Distillate
Bombay High Crude
yield 65-70% (Light distillate 24%, Middle distillates
46%), High aromatics.
46 oAPI, Sulphur 0.1%, Pour point 3 oC, Distillate yield
Narimanam Crude
80%.
36 oAPI, Sulphur 0.1%, Pour point +30 oC, Distillate
KG Basin Ravva Crude
yield 61%.
Source: Mishra & Unnikrishnan, 1996, p.22
REFINERY PROCESSES
Refining 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
181 



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
182 Figure M-VI 1.2: Typical Refinery Processes and Products
Thermal processes:
183 

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 PROCESSES
PRIMARY 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 CAPACITY
Global 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].
184 Table M-VI 1.5: Global Oil Consumption and Refining Capacity 2009
million barrel/d
Region
Oil consumption
25.99
22.83
19.37
Refining
capacity
26.81
21.13
24.92
Asia Pacific
North america
Europe and
Eurasia
S & cent
.America
Middle east
Africa
Total
Remarks
Just matching
Deficit
Surplus
5.65
6.69
Surplus
7.15
3.08
84.04
7.86
3.26
90.66
Surplus
Surplus
Surplus
Source: Samanti,R.K. “Refining challenges and Trends.6th Summer School on “ Petroleum refining and
petrochemicals” June 6,2011, Organised by New Delhi
RUSSIAN
FED., 6%
CHINA, 10%
JAPAN, 5%
S. KOREA,
3%
INDIA, 4%
ITALY, 3%
USA, 19%
S. ARABIA,
2%
OTHERS ,
45%
GERMANY,
3%
Figure M-VI 1.3: World Refining Capacity Country wise 2009
Total: 90.7 mbpd (4533 MMTPA)
Sources: Mr. R.K. Samtani, DGM (Exploration & Production) IOC ltd. 6th June 2011
185 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.
Regular Premium
150
150
Euro-IV Eqv .
Regular
Premium
50
50
Sulphur,ppmw 1000
500
(max)
RON,Min
88
88
91
95
91
95
MON,Min
No
No
81
85
81
85
spec.
spec.
AKI,Min
84
84
81
85
Benzene
5
3
1
1
1
1
vol%(max)
Aromatics
No
No
42
42
42
35
vol%(max)
spec.
spec.
Olefins
No
No
21
18
21
81
vol%(max)
spec.
spec.
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
820-860
Euro-III
Equ.
820-845
Euro III
Equiv.
820-845
Density@15oC
Kg/m3
Sulphur content
ppmw(max)
Cetane
820-860
2500
500
350
50
48
48
51
51
186 number(min)
Distillation
370
370
360
360
99% Vol (oC
max)
Polycyclic
No spec. No spec
11
11
aromatics
hydrocarbons
(PAH),%
massmax
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 STREAMS
For 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 Streams
Streams
Fuel Gas
FCC
Ethylene
Propylene
Butylene
Utilization
H2
Ethyl Benzene to Styrene
Cumene, Iso-Propanol
Methyl Ethyl Keton, MTBE,
Xylenes
Propylene + H2
Discussed Separately
BTX
TAME
LPG, BTX
Aromatics
n-paraffins to LAB
Mixed Naphthalenes
α-Olefins
C3
C4
LPG
C5
Light naphtha
Heavy Naphtha
Kerosene
LCO (FCC unit)
Coker Kerosene
Sources: M. O. Garg Director Indian Institute of Petroleum, Dehradun 23 rd National Convention of
Chemical Engineers IIT Roorkee, 5 – 7 October 2007
187 REFERENCE
1. Garg, M. O., Invited talk 23 rd National Convention of Chemical Engineers IIT Roorkee, 5 –
7 October 2007
2. Mishra, A.K, Unnikrishnan, A., “Overview of the quality of crude oils processed in India”
1996, p.22 Challenges in crude oil evaluation: edt. Nagpal, J.M., New Delhi, Tata McGrawHill Publishing Company Ltd, 1996, p. 1.
3. Mukhulyonov, I.U., Kuznetsov, D., Averbukh, A., Tumarkina, E., Furmer “Chemical
Technology” Mir Publishers Moscow,1974
4. Rajgopal, S., “Petroleum refining and petrochemicals” Refining challenges and Trends 6th
summer School on June 6,2012, Organised by New Delhi
5. Ravindranath,K., Habubula,M. “Hydro carbon condensate Fractionation in oil and gas
processing complex”, Chemical Engineering world, Vol 27, No.10, 1992, p.43
6. Samanti,R.K., “Refining challenges and Trends” 6th summer School on “ Petroleum refining
and petrochemicals” June 6,2012, Organised by New Delhi
7. Samtani R.K., DGM (Exploration & Production) IOC ltd. 6th June 2011
8. Singh, S., Vaidya,S.M., “The benefits from refinery and petrochemical Integration”
Chemical Industry digest August 2012,p67
9. Speight J.G. “The chemistry and technology of Petroleum”, Marccel Decker, Inc, New York,
1999.
10. Venkatraman, N.S., “Algae biofuel could be India’s savior” chemical News July, 2012, p.40
188