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.