COMPOSITION OF CRUDE OILs.ppt has been given

composition has to be cheked for detials as provided

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CRUDE OILS-CLASSIFICATION,COMPOSITION &
CHARACTERISATION FOR FUELS AND LUBES
BY
SK Chhibber

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CRUDE OIL
Naturalorganicmaterialcomposedof
Principallyhydrocarbons
Liquidpartfreefromdissolvedgasis
commonlyreferredascrudeoil.
Physicallycrudeoilvariesfromlight,
mobiletoheavyviscoussemisolid
blackincolour.

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COMPOSITION OF CRUDE OIL
Compositionnotonlyvariesfromdifferent
locationsbutcanalsovaryfromadjacentwell.
Crudeoilisconsistofhydrogenandcarbon
thusnamedashydrocarbons.
Besideitcontainsulphur,nitrogenandoxygen
inasmallerportion.
Alsocontainsmetallicconstituentsintracesi.e.
Vanadeium,Nickle,Iron,Copper.
Waterisalsopresentasanemulsioncomprise
ofsodium/magnesiumchlorideCalcium/
magnesiumSulphates.

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ELEMENTAL
COMPOSITION(%)RANGES FOR
CRUDE
Carbon83.9-86.8
Hydrogen11.0-14.0
Sulphur0.06-8.0
Nitrogen0.02-1.7
Oxygen0.08-1.8
Metals00-0.14
MainlyvanadiumandNickel(Iron,magnesium
,Aluminum,Copper,Silverintraces)

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PRINCIPAL TYPES OF
HYDROCARBON PRESENT
Paraffins
OpenChainsaturatedCompoundedhaving
generalformulaC
nH
2n+2
Thesecompoundarechemicalstable.
Theycouldbenormalparaffin'shaving
straightchain,BrachedChainknownasiso
paraffins.

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NAPTHENES
Knownascycloparaffinshaving
generalformulac
nH
2n.
AreSaturatedhydrocarbons
Highdegreeofchemicalstability.

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Aromatics
These are unsaturated
hydrocarbonshavinggeneralformula
C
nH
2n-6,C
nH
2n-12etc
Arechemicallyreactive.
Formbothsubstitutionoraddition
products.

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OLEFINS
Unsaturated open chain
hydrocarbons.
Arevirtuallyabsentinvirgin
crudeoil.
GeneralformulaC
nH
2n

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NON HYDROCARBON
CONSTITUENTS OF CRUDE OILS
Compounds of sulphur,Nitrogen:-Oxygen
are distributed in entire boiling range.
Increases with increasing boiling point of
crude oil fraction
Sulphur is present in the form of hydrogen
sulphide,mercaptans,sulphides,disulphides
,cyclic sulphide,thiophene & elemental
sulphur
Oxygen compounds:-present in the form
of organic acid (napthenic acid) phenols
alcohols, esters, furans

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These compounds effect the colour
stability, gum formation and corrosive
action during crude processing
NITROGEN COMPOUNDS
Are in the form of Pyridine ,Quinoline ,Iso
quinoline,Pyrole,Indole

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METALIC CONSTITUENTS
Thesearepresentintraces.
Areoforganic/inorganicnature.
Metalshavebeenfoundintheallofpetroleum
resourcesandpetroleumfractions,maybesalt
oforganicacid
Nickle,vanadium&IronhoweverNI,CU,&V
maybepresentasorganiccomplex.

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CLASSIFICATION OF CRUDE OIL
.Classificationprovidecompositionalinformation
basedonsimplemeasurabletest.
Thesetestsarechemicalphysicaland
imperical.
Assessthequalitiesofcrudeoilitself.
Assessyieldandvariousmarketableproducts
thatcanbeobtainedfromit.
Enablesrefinerstodetermineswhat
combinationofproductswillbestmeetthe
requirementoftheprevailingmarket.

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GENERAL CLASSIFICATION
Praffinicbase.
Intermidiateandmixbase.
Napthenicbase.
Crudeoilcanbeclassifiedusingvarious
parameters

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US BUREAU OF MINES METHOD
Base Sp.gravity15ºCSp.gravity15ºC
Fraction250-275ºC 275-300ºC
boilingbetween at40mmHg
Paraffinic0.8251orlighter0.876orlighter
Intermediate0.8251-0.86020.934-0.8762
Napthenic0.8602orheavier0.934/heavier

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CHARACTERISATION FACTOR
K=3√TB
Sp.gravity @ 15ºC
TB=Boiling point in degree Rankin i.e. ºF+460
Paraffin base K=12.1
Intermediate base K=11.5-12.1
Napthenic base K=11.5 or lower

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BUREAU OF MINES CO-
RELATION INDEX
BMCI= 46646/ºK+473.7g—456.8
ºK = Avg. boiling point in degree Kelvin (i.e.
ºC+273 )
g= Sp.gravity @15ºC
Paraffinic BMCI < 15
Intermediate 15—50
Napthenic > 50

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VISCOSITY GRAVITY CONSTANT
VGC= 10G—1.0752 log (V—38 )
10—log(V—38)
G= Sp.gravity @15ºC
V = Viscosity in Say bolt universal
Paraffin 0.80-0.83
Intermediate 0.83-0.88
Napthenic 0.88-0.95

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DIFFERENCE BETWEEN
PARAFFINC & NAPTHENIC BASE
Paraffnic Napthenic
SP.gravity of crude Low High
Yield of gasoline High Low
Octane no.(St. run) Low High
Sulphur content Low High
Smoke pt.Kerosene High Low
Cetane value HSD High Low
Pour point of HSD High Low

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Cont:-
Yield of lubricant High Low
V.I of lubricant High Low
Mixed base crude's have properties
intermediate between the two types
In general paraffin crude yield good
quality kerosene, gas oil, lubricants while
napthenic crude yield good quality
gasoline & bitumen

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ESSENTIAL PHYSICO-CHEMICAL
PROPERTIES OF CRUDE OIL AND
THEIR SIGNIFICANS
Specific gravity
Used for bulk oil measurement
Gives rough indication about the type of crude
API gravityis extensively used and related141.5─131.5
Low specific gravity oil will have high API gravity &vice
versa.
Sp gravity at 15°c

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Cont:-
Distillation
Gives rough & rapid idea about the yield of
various products in the crude oil.
It is an empirical method for comparing of
various crude oils
Pour point
Indicative of flow pattern of crude oil
For estimating relative amount of wax

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CONT:-
Viscosity
Used for pumping & pipe line design
calculations.
For waxy crudes the value depends upon
thermal history of sample and treatment with
flow improver if any
Carbon residue
Indicates coke forming tendency of crude
CCR, RCR, micro carbon residue.

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CONT:-
Sulphur
Undesirable in crude
Even in small quantity causes corrosion & foul
smell.
Cost of its removal or rendering it harmless is
high
Salt content
Crude oil contains small amount of chlorides
of sodium.

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CONT:-
calcium and magnesium due to the contact of crude oil with
oil field brines
It is a major cause of blocking of heat exchanger and cocking
of pipe still heaters. It should be below ten lbs. of salt / 1000
barrels.
Water & sediments
Leads to difficulties in processing, causing irregular behavior
in distillation units leading to blocking heat exchanger.
Settling,heating,chemical treatment or electrical precipitation
adopted for the removal of water & sediments.

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CONT:-
Wax content.
There is no std. method for crude oil
Common method consists of filtering &
measuring the wax ppt.from a solution of
crude oil in methlene chloride cooled to –5 ºC.

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EVALUATION OF CRUDE OIL
General purpose of evaluation & data generated will
enable refiners to assess the yield and properties of st.
run derived from it.
Main objectives
To assess the yield & properties of St. run products
Indicates what further processing/ treating is required
to meet the requirements of the specification
To indicate the cost of secondary treating

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CONT:-
What combination of products will best meet
the requirements of the market
Assessing the cost of crude oil.

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TYPES OF EVALUATION
Preliminary Evaluation
Important basic properties of base oil
Distillation data generated through a semi fractionating
or non-fractionating distillation.
Short evaluation
Physico chemical properties of crude oil
Fractionating TBP distillation data upto diesel
recovery.
Yield & some key characteristics of major st. run
product (Naptha,kerosene,gas oil,&atmosphric
residue

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CONT:-
Detailed evaluation
Physico-chemical properties of crude oil
TBP distillation assay (Atmospheric & vacuum
Detailed studies on several st. run cut in fuel
oil, lube oil & secondary processing feed stock
and bitumen

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CRUDE DISTILLATION COLUMN

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