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1 / 60 E351A
E351A
by Jean-Louis Salager,Lab. Formulation, Interfaces, Rheology and ProcessesChemical Engineering School,University of the AndesMrida, Venezuela
A presentation for EniTecnologie, Milano-Italia, Oct. 2nd, 2002 2 / 60 E351A
3 / 60 E351A
What is a Surfactant ?
SO3 Na+-
Dodecyl Benzene Sulfonate Sodium Salt
Lipophilic / Hydrophobic (non polar) Group
Hydrophilic Group(polar)
Usual representation
4 / 60 E351A
12 25
O
OC H O S O Na
Dodecyl (ester) sulfateSodium Salt (foaming agent)
ANIONIC
CATIONICN
C H12 25
Cl -+
n-DodecylPyridinium Chloride
(desinfectant)
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pH 8C H
CH -CH -COO
12 25
2 2-
CH -N-CH3 3+
n-Dodecyl Betaine(cosmetic Soap)
AMPHOTERICor
ZWITTERIONIC
NONIONIC
H C3 OH C3 O
P-C HO
14 29
Dimethyl ether of TetradecylPhosphonic Acid (agro-emulsions)
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ADSORPTIONADSORPTION at interfaces ASSOCIATION ASSOCIATION in solution
ADSORPTIONADSORPTION ASSOCIATIONASSOCIATION
All Surfactants exhibit2 Fundamental Properties :
bactericideSome are
7 / 60 E351A 8 / 60 E351A
ADSORPTION at interface
oil air
water water
water
NonpolarSolid
The Surfactant molecule adsorbsat interface to satisfy its dual affinity
9 / 60 E351A
ADSORPTIONliquid-liquid interface
low tension emulsification capillarity speading adhesion instability
adsorption
10 / 60 E351A
ADSORPTION solid-liquid interface
hydrophobation lubrication flotation wetting detergency
adsorption
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ADSORPTION Dispersions
= stabilization mechanisms foremulsions, suspensions and foams
electrostatic orsteric repulsion
drop, bubble, particle
drop, bubble, particle
Liquid Film
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13 / 60 E351A
ASSOCIATIONin solution
is spontaneous results in G < 0 reduces the contact between the solvent
and the solvent-hating group results in an organized structure:
normal or inverse micelle liquid crystal, microemulsion bilayer, membrane, vesicule, liposome
micelle
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Equilibrium between structures
sphericalmicelle
cylindricalmicellelamellar liquid crystal
surfactant in solution
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A Liquid Crystal is ... not a liquid ... nor a crystal
It is not stchiometric and can take up ...
water
oil solid
liquid
water
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Many Cases of Application Drilling Muds Acid Stimulation Injection control Asphaltenes control Enhanced Oil Recovery Crude Deshydration Emulsified Fuels Asphalt Emulsions etc ...
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Drilling Fluids should ...Cool and lubrificate the drilling bitTake away suspended cuttingsCounter-pressure & anti-filtration effects
mud
Bit
oilwater
cuttingclay
p
pp
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Drilling Fluids(water base)
water (cools, disolves and suspends things ) clays (viscosity, rheology) additives to increase density oil (lubrificates, facilitates drilling) surfactants (dispersants, emulsifiers) polymers (filtration control, rheology) etc ...
contain :
Lets see the role of some ingredients!
20 / 60 E351A
Dispersing Agentsfor suspended solids
Should pull apart (clay) particles Should counter (clay and barite) flocculation Should provide plasticity and thixotropyLignin Derivatives, LignosulfonatesTanins (quebracho)Polyelectrolytes
reduce clay swelling emulsify
oilshelp controlling fluid losses
Ecological
Problems wi
th
Chromium sa
lts
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gasoils, residues, asphalts ... mono di-esters of vegetal oils from 5 to 15 % oil content
Other Surfactants(emulsifiers, foamers)
emulsify oils foaming and antifoaming agents corrosion inhibitors polymer activators
p
more
ecologi
cally
friendly
Oils22 / 60 E351A
Polymers(viscosity control)
polysacharides, polyacrylamides (pseudo) plastic rheology
special polymers associative, thermoassociative hydrophobically modified interactions with surfactants T
HIXOTRO
PY
PROBLEMS : biodegradation and thermodegradation
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Example of Surfactant-Polymer Interationanionic surfactant - polyethylene glycol
necklace type
100 EO unitsby SDS micelle
PEG
SDS Micelle
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Shear thinning RheologyVery fluid athigh shearin nozzle
newtonian fluid
plastic fluidbetter cleaning near wall !
reduces caking !
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Polymers(for filtration control)
natural polymer (xanthane, starch, gums) natural modified polymer (CMC, HEC) synthetic (part. hydrolized polyacrylamide) ... eventually + surfactants
1. Cover clay particles2. Link particles3. Gelify water
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Acid Stimulation a W/O emulsion is injected W = (HF+HCl) aqueous solution
Emulsion ofacid inaromatic gasoil
Porous medium
Sandgrain
attackacid
Gas oil
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Injection Problems due to Gravity Segregation
Steaminjection
Low oil saturation
High oilsaturation
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Foam Injectionto plug cracks and
high permeability zonesFoamingliquid
Pluggingfoam
Gasbubble
gaz
Porousrock
crack Sandgrain
Foam Plug
N2 gasorsteam
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Production of Petroleum + Water
Dehydration
Water must be separated (it is generally emulsified water)
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valve
tube,elbow
pump
defectivepump
gas
leak
incomingforeignsubstances
Emulsion formationrequires O + W + S
+ mixing
Where are W/OEmulsions formed ?
stirring - mixingin variouslocations
31 / 60 E351A
Natural Surfactants ? Polyaromatic molecules as asphaltenes
NH N
HNNNi
N N
NNMg
CH2
H C3
CH
CO C H2 20 39
CH2CH3
CH2CH3
CH3
OCO CH2 3
H C3
H C2chlorophyll
Degradation,ion exchange
e. g. porphyrin structure
contains at leastone polar group
32 / 60 E351A
Natural Surfactants ?
macromolecules (very) lipophilic flat ... cockroache piled up aggregates containing ... ... a few molecules
polar group
legs
= micelle= micelle
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Natural Surfactantsstabilize W/O emulsions
Waterdrop
PetroleumWaterdrop
Waterdrop
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Bottle testin practice
originalW/ Oemulsion
Add x ppmdehydrant
Homogenize
Pour inbottle
wait some time
Measure water separation
crude
water
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naturalsurfactant
efficientMixturedehydrantsurfactant
unstableemulsion
- SAD = 0 +corresponds to
Aspect of bottles (at variable formulation, concentration or dehydrant type)
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Orimulsion = Emulsified Fuel Heavy crude oil in water emulsion
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Emulsified Fuels O/W (or W/O)
the presence of water in a fuel-> reduces the burning temperature -> reduces corrosion and NOx formation-> increases gas density and Cp -> favors heat transfer -> reduces scale formation
pre-atomization makes combustion easier better control of oil spills available treatments (metals, sulfur, ashes)
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If 1/3 of this residual oil is producedultimate recovery is x 2
at 10 $/bbl benefit : 66 x x 10101212 $ $R&D incentive for EOR
Enhanced oil recovery
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First, only oil is produced
Then a oil + water mixture is produced, asituation that goes on with water flooding
Finally oil residual saturation is attained(Sor) and only water is produced
Capillary Trapping of Oil40 / 60 E351A
saturationOIL WATER
rela
tives
per
mea
bilit
ies
ko kw
2 Phase Flow
2 phases
Sor
Productionhistory
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WATEROIL
Pres
in
Cap
ilar
1 oil injectionrst
Waterinjection
oilinjection
2 phase motion in porous mediaimbibition and drainage
hysteresiscycle
Cap
illary
Pre
ssur
e
Saturation = memory
42 / 60 E351A
advancing > receding
Contact Angle Hysteresis
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This complicates the motion problem
Because even in a cylindrical capillarya non-zero P is required to induce motion !
P = 0 P > 0
Without hysteresis With hysteresisadvancing > receding
Even worse if the capillary is not cylindrical
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Poiseuille P = v
Laplace P = 2 ( - )1R 1R 1 2
Hysteresis due to geometry
coniccapillary
LAPLACE Law :
P is curvedinterface
= 2 / R
45 / 60 E351A
1
2
3
(1) when water is injectedit penetrates into thesmaller diameter pore(Laplace P)(2) then oil moves back intothe larger pore(3) and finally getsdisconnected from other oiland ends up trapped
oil
2 cylindrical capillarieswith different diameters
Hysteresis due to geometry46 / 60 E351A
Typical situation after waterflooding
disconnected Globulesresidual saturation 30 %
P Laplace >>> P Poiseuille
P Laplace = 2 / RP Poiseuille = v L
Capillary Number NCa v = = 10 -6
Mobilization requires a x 1000 increase
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Correlation NCa Recovery
NCa = v
Resi
dual
Sat
urat
ion
S or
10 - 4 10 - 210 - 6 10 - 4 10 - 210 - 6
Viscous forces
Capillary forces
48 / 60 E351A
which alter capillary number Increase in v or Reduction in interfacial tension Wettability change
which alter saturations (phase volumes) Oil Swelling Oil Solubilization
others and combined mechanisms Miscibility (surfactant, CO2 sc) Emulsification (spontaneous or not)
Mobilization Mechanisms
49 / 60 E351A
hydrocarbon-water = 1-10 mN/m hydrocarbon-surfactant solution 0.1 mN/m
near optimum formulation 0.001 mN/m
which alter capillary number bydecreasing tension (ultralow )
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ASP Process Engineering
1 injector 4 Producers
oil bank
injection in a 5-spot pattern
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General Principle Trapped oil is mobilized by something expensive ($$$)
which is injected as a narrow slug Mobilized oil moves forward and increases saturation
beyond Sor, Which results in an oil bank (2 phase flow) Everything is pushed by something viscous Which is in turn pushed something cheap (water)
$$$$
Sor
Sor
injec
tion
prod
uctio
n
saturation
drivewater
mobilitybuffer
oilbank
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At optimum formulation
Minimum Tension Easy Deformation Easy Emulsification
Low Viscosity Emulsion Very Unstable Emulsion
Can be different if formulation is off optimum as in thecase of pure alkaline flooding stable emulsion
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Asphaltenes Asphalt EmulsionsStructured Dispersions
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PROBLEM
Asphaltenes form colloids inapolar medium
slightly polarmacromoleculesthat are able to aggregate in micelles (stable colloid)
form deposits
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Colloids in apolar medium(asphaltenes)
Asphaltenic micelles can be stabilizedby resins (= surfactants or dispersants whichare even less polar than asphaltenes)
resinresin
asphalteneasphaltene
crude
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Asphalts are fluidized by solvent dilution heating emulsification
Asphalt Emulsionsfor road pavement
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Asphalt Emulsions
adsorption on rockadsorption on rock
ElectrostaticRepulsion
flocculation
hydrophobationhydrophobation
adhesionadhesion
Equilibria
1
2
2
3
3
4
breaking
4
58 / 60 E351A
(acid) Corrosion Inhibition
waterH+ H+
Me Me Me
electrochemicalreaction =corrosion
adsorptionof H +
Me MeH2
Me++
adsorptionof cationicsurfactant
H+X
Me Me Me
protectionagainstcorrosionMe Me Me
hydrophobation
H S HS + H HS S + H2+ +- - - -
59 / 60 E351A
Single layer structure in apolar medium results inWater in oil mini / microemulsion
waterdroplet
DIESELFUEL
100 - 1000 nm
60 / 60 E351A
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