Origin and Composition of Crude Oil.pdf

Different ages of fossil fuel formation, time-line of crude oil formation, Organic Vs Inorganic theory for crude oil

1. Unit-2: Liquid Fuels
Prepared by:
Ankur Sachdeva
Assistant Professor, ME

2. What is Crude Oil?
•ThewordpetroleumoriginatedfromtheLatinwords,
Petra,meaningrockandoleum,meaningoil.
•Literallyitmeans‘RockOil,’andcanalsobedefinedas
anon-renewablefossilfueloroilthatisfound
underground.
•Thisisanynaturally-occurringflammablemixtureof
hydrocarbonsfoundingeologicalformationssuchas
rockstrata.
•Technically,thetermpetroleumreferstodescribeany
solid,liquidorgaseoushydrocarbons.
•It’salsoknownas‘crudeoil’or‘mineraloil.’

4. Origin of Petroleum
•Petroleumisscatteredthroughouttheearth’scrust,
whichisdividedintonaturalgroupsorstrata,
categorizedinorderoftheirantiquity.
•Thesedivisionsarerecognizedbythedistinctive
systemsoforganicdebris(aswellasfossils,minerals,
andothercharacteristics)thatformachronological
timechartthatindicatestherelativeagesoftheearth’s
strata.
•Itisgenerallyacknowledgedthatcarbonaceous
materialssuchaspetroleumoccurinallthese
geologicalstratafromthepre-Cambriantotherecent
times.

5. Geological Time Scale

6. Origin of PetroleumDilemma
Inorganic or Abiogenic Theory
Vs
Organic or Biogenic Theory

7. INORGANIC THEORY

8. Berthelot Theory
•In1866,Berthelotconsideredacetylenethebasic
materialandcrudeoilconstituentswereproduced
fromtheacetylene.
•Initially,inorganiccarbideswereformedbytheaction
ofalkalimetalsoncarbonatesafterwhichacetylene
wasproducedbythereactionofthecarbideswith
water.

9. Mendelejeff Theory
•Mendelejeff,whoproposedthattheactionof
diluteacidsorhotwateronmixedironand
manganesecarbidesproducesamixtureof
hydrocarbonsfromwhichpetroleumevolved,
describedanothertheoryinwhichacetylene
isconsideredtobethebasicmaterial

10. Other Inorganic Theories
•Thishypothesisofpetroleumoriginwithoutbiologywas
firstproposedin16thcenturybyGeorgAgricola,thenin
19thcenturybyAlexander(Prussiangeographer),Dmitri
(Russianchemist),Marceline(Frenchchemist)andre-
definedin20thcenturybyCornellUniversityphysicist,
ThomasGold.
•Supportersofthishypothesisarguedthathydrocarbons
existedattheformationofthesolarsystemandwere
abundantinotherThomasGoldplanetse.g.Saturn,Jupiter
•Thetheoryarguedthatpetroleumoriginatedfromlimitless
poolsofliquidprimordialhydrocarbonsatgreatdepthsin
theearth.
•Thesecarbon-bearingfluidsmigratedupwardfromthe
mantlewheretheyslowlyreplenishthereservoirsthat
conventionaloildrillerstap.

11. Abiotic Theory
•OtherhypothesisaroseasaresultoftheAbiotictheory.
Theseinclude:
•i.Deepseatedterrestrialhypothesis.
•ProposedbyDmitriMendeleev,hepostulatedthatmetallic
carbidesdeepwithintheearthreactedwithwaterathigh
temps.formingacetylene.
•CaC
2(s)+2H
2O Ca(OH)
2(s)+C
2H
2(g)
•ii.Extraterrestrialhypothesis.
•ProposedbySokoloff,hebasedacosmicoriginto
petroleumorigin.Hepostulatedthathydrocarbons
precipitatedasrainfromoriginalnebularmatterfrom
whichthesolarsystemformed.

12. Conclusions of Abiogenic Theories
•Largeamountsofcarbonexistnaturallyinthe
planet,someintheformofhydrocarbons.
•Hydrocarbonsarelessdensethanaqueous
porefluidsandmigrateupwardthroughdeep
fracturenetworks.
•Thermophilic,rock-dwellingmicrobiallife-
formsareinpartresponsibleforthe
biomarkersfoundinpetroleum.

13. Biogenic Origin
•Petroleumisanaturallyoccurringhydrocarbonmixture
buthydrocarbonsthataresynthesizedbyliving
organismsusuallyaccountforlessthan20%ofthe
petroleum.
•Theremainderofthehydrocarbonsinpetroleumis
producedbyavarietyofprocessesthatconvertother
organicmaterialtohydrocarbonsaspartofthe
maturationprocessesgenerallyreferredtoas
diagenesis,catagenesis,andmetagenesis.
•Thesethreeprocessesareacombinationof
bacteriologicalactionandlow-temperaturereactions
thatconvertthesourcematerialintopetroleum.

14. Biogenic Theory
•Mostgeologistsviewcrudeoilandnatural
gasastheproductsofcompressionand
heatingofancientvegetationovergeological
timescales.
•Accordingtothistheory,itisformedfrom
thedecayedremainsofprehistoricmarine
animalsandterrestrialplants.
•Overmanycenturiesthisorganicmatter,
mixedwithmud,isburiedunderthick
sedimentarylayersofmaterial.
•Theresultinghighlevelsofheat(60˚Cto
200˚C)andpressurecausetheremainsto
metamorphose,firstintoawaxymaterial
knownaskerogen,andthenintoliquidand
gaseoushydrocarbonsinaprocessknownas
catagenesis.
•Thesethenmigratethroughadjacentrock
layersuntiltheybecometrapped
undergroundinporousrockscalled
reservoirs,forminganoilfield,fromwhich
theliquidcanbeextractedbydrillingand
pumping.

16. Organic Theory
•Duringthepast600millionyears,incompletely
decayedplantandanimalremainshavebecome
buriedunderthicklayersofrock.
•Itisbelievedthatpetroleumconsistsofthe
remainsoftheseorganisms,butitisthesmall
microscopicplanktonorganismremainsthatare
largelyresponsiblefortherelativelyhighorganic
carboncontentoffine-grainedsedimentslike
shalethatarebelievedtobetheprinciplesource
rocksforpetroleum.

17. Organic Theory

18. Accumulation of Petroleum
•Sourcerocksarerocksthat
containsufficientorganic
material to
createhydrocarbonswhen
subjected
toheatandpressureover
time.Sourcerocksareusually
shalesorlimestones
•A reservoirrockis
arockcontainingporosity,
permeability, sufficient
hydrocarbonaccumulation
andasealingmechanismto
formareservoirfromwhich
commercial flows of
hydrocarbonscan be
produced.
•Caprocksarerelatively
impermeablerockslayersthat
sealthetopofreservoirsand
othergeologicformations.

19. Accumulation of Petroleum

20. Composition of Petroleum
•Thelargestsourceofliquidfuelsispetroleum.The
calorificvalueofpetroleumisabout40000kJ/kg.
Thereareothersupplementsofliquidfuelssuchas
coaltar,crudebenzol,syntheticliquidfuelmadefrom
coaletc.
•Composition:
Carbon=83.0%to87.0%
Hydrogen=10.0%to14.0%
Sulphur=0.05%to6.0%
Nitrogen=0.1%to2.0%
Oxygen=0.05%to1.5%
Metals(NiandV)<1000ppm

21. Composition of Petroleum
•Sulphurispresentintheformofderivatives
ofhydrocarbonssuchasalkyl-sulphides,
aromatic-sulphidesetc.
•Nitrogenispresentintheformofpyridine,
quinolinederivatives,pyrroleetc.
•Combinedoxygenispresentascarboxylic
acids,ketonesandphenols.
•Theashofthecrudeoilis0.1%.Metalse.g.,
Silicon,iron,aluminium,calcium,magnesium,
nickelandsodium

22. Molecular composition
Molecularcompositionofpetroleumcanbedescribedintermsof
threeclassesofcompounds:
•Saturates,aromatics,andcompoundsbearingheteroatoms(sulfur,
oxygen,ornitrogen).
•Withineachclass,thereareseveralfamiliesofrelatedcompounds:
(1)saturatedconstituentsincludenormalalkanes,branchedalkanes,
andcycloalkanes(paraffins,iso-paraffins,andnaphthenes.
(2)alkeneconstituents(olefins)areraretotheextentofbeing
consideredanoddity,
(3)monoaromaticconstituentsrangefrombenzenetomultiplefused
ringanalogs(naphthalene,phenanthrene,etc.),
(4)thiol(mercaptan)constituentscontainsulfurasdothioethersand
thiopheneforms,
(5)nitrogen-containingandoxygen-containingconstituentsaremore
likelytobefoundinpolarforms(pyridines,pyrroles,phenols,
carboxylicacids,amides,etc.)thaninnonpolarforms(suchasethers).