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The Effects of Mesitylene on the Cold Flow Properties of Model Crude Oils


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Introduction
Theory and Background
The Effect of Mesitylene on the Cold Flow Properties of Model Crude Oils
UgochukwuOkeibunorandMichaelSenra
Department of Chemical and Biomolecular Engineering, Lafayette College, Easton, PA 18042
Experimental Methods
Results and Analysis
Future Work
References
[1]Senra,M.,Scholand,T.,Maxey,C.,
&Fogler,H.S.Role of polydispersity
and cocrystallization on the gelation of
long-chained n-Alkanes in solution.
Energy & Fuels,235947-5957.Nov.
2009.
[2]NurFatmala.Wax in Subsea
Pipelines,February2016.WebAugust
7
th
2017.
Thecoldflowpropertiesofafluidrepresentits
movementandcharacteristicsatlowtemperatures.These
propertiesareoftendictatedbyhowtheprecipitated
solutesformcrystals.
Conclusions

v Microscopycanbeusedtoanalyze
thecrystalstructuresofthegels
formedinthisworktobetter
validatetheresultsandhypotheses.
v Increasinglycomplexn-alkane
systemscanbestudiedtodetermine
iftheeffectsseenformodelcrude
oilscanbeextendedtoactual
crudes.
Figure 2.Cross-polarizedmicroscopyimagesforslowlycooledn-alkane
solutions.Panela)for4%C36solutionsat33°C,panelb)for4%C36/5%
C28solutionat25°Candpanelc)for4%C36/6%C32solution[1]
Acknowledgements
ThankstotheLafayetteCollegeEXCEL
programandtheDepartmentof
ChemicalEngineeringforfacilitatingthe
completionofthisproject.
Thedepositionofwaxinsubseaoilpipelineshas
beenamajorprobleminflowassurance.Theseformed
geldepositscanreduceoilproductionandoncethey
occur,arecostlytoeliminate.
Figure 1.Waxformedin
pipeline[2]
Figure 4.TAInstrument
DiscoveryHR-2
rheometer
Figure 5. Storageandloss
moduliofafluidunder
stress
q Smallaromaticmoleculescan
influencethethermodynamicand
gelationcharacteristicsofmodel
crudeoils.
q Theireffectscanbeafunctionofthe
amountofaromaticpresentandthe
complexityofthecrudeoil.
q Themechanismsbywhichthe
aromaticinfluencesthesystemare
widelyvaried.
q Properpredictionofcrudeoil
gelationshouldrequireinformation
aboutthearomaticscontent.
Figure6showsthatthegelpointoftheC36
systemincreasedfrom33.5°Cto40°C,whilethegel
pointoftheC32systemhadaslightincreasefrom
28°Cto30°C.Ahypothesisforthisbehavioristhat
increasingmesityleneconcentrationsdecreasethe
solubilityofC32andC36indodecane,thuscausing
gelationtooccurathighertemperatures.
Figure8showsthatthecloudpointrange
wasabout2°Cforallsystems.However,
monodispersesystemsshowedaslightupward
trendwhilepolydispersesystemsshowedaslight
downwardtrend.Foreachmesitylene
concentration,thegelpointobtainedby
differentialscanningcalorimetrywasgenerally
about2°Clower,butsimilartrendswereobserved.
Figure 6.GelPointTrendforMonodisperseSystems.
Figure 8.CloudPointsforthen-alkaneSystemsObtainedbyCalorimetry
Figure7showsthatforbothsystems,aninitial
increaseinmesityleneconcentrationby1%-2%
causedasharpdecreaseinthegelpoints.Athigher
concentrations,thegelpointsrosesharplyand
remainedrelativelyconstant.Itishypothesizedthat
lowamountsofmesitylenedispersestheformed
crystals,whilehighamountsofmesitylenecanself-
aggregate,limitingtheirinfluenceonthecrystal
structure.
a)
b)
c)
Figure 7. GelPointTrendforPolydisperseSystems
Inthiswork,dodecane(C12),octacosane(C28),
dotriacontane(C32)andhexatriacontane(C36)served
asmodelcrudeoils.Theaimofthisworkwasto
investigatetheeffectsofmesitylene,asmallorganic,on
thecoldflowcharacteristicsofthesemodelcrudeoils.
PreviousworkhasshownthatC36(Figure2a)
formslargecrystals,producingavolume-spanning
networkthatisconducivetogelation.However,adding
anothern-alkanecaninfluencehowthesecrystalsform.
C28dispersesC36fromforminglargeanduniform
crystals(Figure2b),whileC32reducesthegelationof
C36byformingcocrystalswithC36(Figure2c).
Studieshaveshownthatn-
alkanes,theprimarycomponentsof
crudeoil,arelargelyresponsiblefor
thisdeposit[1].Thisphenomenon
occursbecauseoftheirlowsolubility.
Figure 3. Chemical
Structure of Mesitylene
Thisprojectaimstoanalyze
theeffectsofasmallaromatic
moleculeonthegelation
characteristicsofdifferentn-alkane
systems.Specifically,theeffectof
addingmesityleneonthegel
formationofthesemodeloil
systemswasstudiedbyrheology.
v Cold flow properties studied in this work were the gel point
and the cloud point.
v The gel point represents the temperature where initial gel
formation occurs and the cloud point represents the
temperature where crystals can first be seen.
v Rheology and differential scanning calorimetry were used to
analyze the pour points and cloud points respectively.
v Experimentation methods ensured elimination of thermal and
shear history by holding sample quiescently at a constant
temperature for a substantial period of time.

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