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FLUCHA II Fluid Characterisation at Elevated Pressures and Temperatures
Prof. Johan Sjöblom, Ugelstad Laboratory
Department of Chemical Engineering
NTNU, Trondheim, Norway
FLUCHA
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FLUCHA II - Ambitions
Characterization of true crude oil systems and emulsions at elevated pressures and temperatures
Establish reference systems which will explain the component –wise behaviour together with their interactions.
Thermodynamic simulations of heavy surface active components (at different P and T).
Experimental characterisation of crude oil/reference systems and corresponding emulsions at elevated pressures.
Performance of chemicals (demulsifiers and inhibitors) at high pressures.
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FLUCHA II - AmbitionsTechnical (industrial) applications (outside the programme)
Transport and stabilization of gas hydrate slurries in oil/gas/water mixtures
High pressure/temperature separation (sub sea / down hole conditions)
Development of sub sea centrifugal separator system (Framo Purification)
Development of chemicals with high pressure performance
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FLUCHA II - OrganisationReference Group (of Sponsors):
NFR Aud Alming
ABB John Dan FriedemannPål Jahre Nilsen
Norsk Hydro Per GrammeLiv Thorsen
Statoil Einar Eng JohnsenArild Westvik
TotalFinaElf Ingvild Andersen Jean-Luc Volle
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FLUCHA II - Employees
Post docsHarald KallevikØystein SætherGisle Øye
PhD Candidates:Inge Harald AuflemNarve AskeTrond Erik HavreLinn Bergflødt / University of Bergen
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Approach: Physico-chemical characterisation
Emulsion stability
Paper III
Crude oil properties
Paper II
Fluid behaviour and control
Crude oil composition
Paper I
Crude oil structure
Papers IV and V
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AsphaltenesHeaviest components of the crude oil, molecular weight 500-1500.
Contains heteroatoms (O, S, N) and metals (Ni, V, Fe).
Polar molecules with high interfacial activity.
Strong tendency of self-aggregation.
Under unfavourable solvent conditions asphaltenes may precipiate as a solid phase.
Stabilises emulsions by forming a rigid, cross-linked interfacial layer.
Courtesy: Prof. J. Murgich
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Prediction of SARA-data by Partial Least Squares Regression (PLS)
ypred = f (X) = b0 + b1x1 + b2x2 +…+ bnxn
PLS
62
…
27
74
45
Saturates
yOil(n)
….
Oil(3)
Oil(2)
Oil(1)
2200nm….1103nm1102nm1101nm
Organize spectral data
X
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Oscillating pendant drop tensiometer
ε, Gibbs interfacial dilatational modulus, measure of interfacial rheology:
Addγεln
= dd iωηε +=
Small, oscillating area deformations:→ Elasticity and viscosity contribution can be separated.
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Elasticity of crude oil/water interfaces
-2.0
3.0
8.0
13.0
18.0
23.0
28.0
4 16 14 6 20 8 9 11 23 21 22 5 19
Crude oil no.
Elas
ticity
[mN
/m]
Elasticity, 0.002 ml/ml
Light crude oils/condensates
Most stableemulsions
Highest inasphaltenes
Demulsifier added
Demulsifier not added
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Critical Electric Field Emulsion Stability Cell
0
0.5
1
1.5
2
2.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7Electric field [kV/cm]
Cur
rent
[mA
]Crude oil 3, WC 30%
I
II I II
ECrit
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Crude oil data matrixOrigin WC20
[KV/cm] WC30
[Kv/cm] S
[wt%] A
[wt%] R
[wt%] Asph. [wt%]
Elasticity [mN/m]
Density [g/cm3]
IFT [mN/m]
Mw [g/mole]
Visc.,25°C [kg/ms]
TAN
West Africa 0.58 0.47 47.9 36.5 15.2 0.4 11.5 0.914 20.5 234 18.7 1.10 North Sea 0.87 0.61 48.0 37.5 14.2 0.3 7.3 0.916 24.8 279 57.4 3.10
West Africa 2.00 0.68 41.2 36.4 20.4 2.1 7.8 0.916 26.4 310 143.0 1.50 North Sea 0.00 0.00 82.7 13.4 3.9 0.0 -1.1 0.839 37.1 166 1.8 0.69 North Sea 1.00 0.64 62.7 23.6 12.2 1.5 16.5 0.844 12.8 201 5.4 0.18 North Sea 0.91 1.03 45.5 37.1 16.0 1.4 3.7 0.862 31.9 244 14.5 0.02 North Sea 2.00 1.50 35.3 36.8 24.5 3.5 11.7 0.945 27.4 333 386.6 2.30 North Sea 0.55 0.45 56.0 29.6 14.1 0.3 6.7 0.850 24.7 216 6.6 0.17 North Sea 0.84 0.59 41.8 38.8 18.7 0.6 8.4 0.914 11.8 284 51.0 3.10 North Sea 0.53 0.33 50.9 34.6 14.0 0.5 5.0 0.885 22.8 234 11.6 2.70
West Africa 2.00 1.85 40.6 32.1 20.6 6.6 10.6 0.888 29.0 260 27.8 0.49 North Sea 0.00 0.00 79.8 16.5 3.6 0.1 -1.4 0.796 34.2 157 1.7 0.01
West Africa 0.61 0.45 57.3 27.9 13.5 1.3 - 0.873 24.6 235 17.7 0.50 North Sea 0.59 0.08 60.6 30.0 9.2 0.2 0.2 0.857 22.9 227 10.5 0.04
West Africa 0.85 0.40 42.4 36.1 20.5 1.0 9.2 0.921 16.2 295 105.8 3.60 North Sea 0.00 0.00 65.0 30.7 4.3 0.0 -0.6 0.796 27.6 142 1.2 0.02 North Sea 0.47 0.42 44.1 41.6 13.8 0.5 8.1 0.847 19.9 223 11.7 0.15 North Sea 0.93 0.43 50.3 31.4 17.5 0.7 14.8 0.898 19.5 249 19.1 1.20 North Sea 2.00 2.00 54.5 28.8 14.9 1.8 24.9 0.840 27.4 298 63.1 0.36
West Africa 0.91 0.72 55.4 28.3 12.9 3.4 5.6 0.873 19.0 248 15.3 0.44 France 2.00 1.70 24.4 43.4 19.9 12.4 12.9 0.939 13.4 303 278.9 0.20
Objective: Correlate emulsion stability to the physico-chemical properties.
Tool: Multivariate analysis (PCA, PLS).
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PLS regression on data matrix
Saturates
Aromatics
Resins
Asphaltenes
t1, NIR
t2, NIR
(S+Asf)/R+A)
R/(R+Asf)
Elasticity
Density
IFT
MW
TAN
ViscosityRe
g. Co
eff.
(ln E
critc
al)
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Saturates
Aromatics
Resins
Asphaltenes
t1, NIR
t2, NIR
(S+Asf)/R+A)
R/(R+Asf)
Elasticity
Density
IFT
MW
TAN
ViscosityRe
g. Co
eff.
(ln E
critc
al)
Saturates
Aromatics
Resins
Asphaltenes
t1, NIR
t2, NIR
(S+Asf)/R+A)
R/(R+Asf)
Elasticity
Density
IFT
MW
TAN
Viscosity
Saturates
Aromatics
Resins
Asphaltenes
t1, NIR
t2, NIR
(S+Asf)/R+A)
R/(R+Asf)
Elasticity
Density
IFT
MW
TAN
ViscosityRe
g. Co
eff.
(ln E
critc
al)
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Correlation coefficient of predicted vs. measured plot: R2 = 0.93
Additional models:1. SARA + interfacial elasticity2. Near infrared spectroscopy data
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High-pressure NIR rig
x x
x x x x
x
Air cabinet
Personal computer
NIR spectrometer
Fibre optics
NIRcell
Cell 1
Cell 2
V1
V2
V3x x
x x x x
x
Air cabinet
Personal computer
NIR spectrometer
Fibre optics
NIRcell
Cell 1
Cell 2x
xx x
x x x
Air cabinet
Personal computer
NIR spectrometer
Fibre optics
NIRcell
Cell 1
Cell 2
V1
V2
V3x x
x x x x
x
Air cabinet
Personal computer
NIR spectrometer
Fibre optics
NIRcell
Cell 1
Cell 2
V1
V2
V3x x
x x x x
x
Air cabinet
Personal computer
NIR spectrometer
Fibre optics
NIRcell
Cell 1
Cell 2x
xx x
x x x
Air cabinet
Personal computer
NIR spectrometer
Fibre optics
NIRcell
Cell 1
Cell 2
V1
V2
V3
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Depressurisation of crude oil
0.4
0.6
0.8
1.0
1.2
1.4
1300 1400 1500 1600 1700 1800 1900 2000 2100 2200
Opt
ical
den
sity
300 bar → 160 bar
155 bar → 150 bar
Wavelength [nm]
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Reversibility of asphaltene aggregation
0.39
0.40
0.40
0.41
0.41
0.42
0.42
140160180200220240260280300320
Pressure [bar]
Opt
ical
den
sity
@ 1
600
nm
0.39
0.40
0.40
0.41
0.41
0.42
0.42
140160180200220240260280300320
Pressure [bar]
Opt
ical
den
sity
@ 1
600
nm
16h
72h
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Paper IHigh-pressure
separation rig
High-pressure separation rig
Crude Water
Emulsification
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0
50
100
150
200
250
300
350
40011->
1
11->
7
11->
1
11->
7
Pressure drop (bar)
Foam
hei
ght,
ml
Main results / Conclusions
Gas cap removed
→ no foam stability
0
10
20
30
40
50
60
70
80
90
100
0.0 5.0 10.0 15.0 20.0
Time [min]%
sep
arat
ed w
ater
11->1 bar (gas cap removed)
11->7 bar (gas cap removed)
11->1 bar
11->7 bar
Paper I
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Paper I
Main results / Conclusions
Coated gas bubble Foam formationDegassing
Gas bubbles that move upwards through the oil phase can remove surface active materialfrom the water interface, thereby improving coalescence and separation
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Patent
Main results / Conclusions
No clear influence on separation from CO2 release
Increased separation upon CO2release after 5 minutes
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Patent
Main results / Conclusions
Pressuredrop
Coalescence
Bubbles ruptures interface
Flotation Film drainage
Bubbles inside droplets
1
2
1) CO2 dissolved into the aqueous phase forms bubbles upon pressure reduction that ruptures the interface
2) 2) CO2 dissolved in the oil phase, propagates through the system ripping of surface active material from the oil-water interface
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Patent
Main results / Conclusions
• A polar gas, such as CO2, can in some cases accelerate the breaking of crude oil based emulsions
• The method is probably useful only for particle stabilisedcrude oil emulsions
• Improved performance if the water droplets are allowed to sediment to form a dense packed region
• The flotation effect is also valid for model oil systems
• The use of flotation can be effective in a gravitational separators, especially of batch type
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Method
Dissipative Quartz Crystal Microbalance (QCM-DTM)
– A QCM consists of a thin quartz disc sandwiched between a pair of electrodes
– Due to the piezoelectric properties of quartz, it is possible to excite the crystal to oscillation by applying an AC voltage across its electrodes
– Measures simultaneously change in frequency,f and dissipation, D
– When a thin film adsorbs to the sensor crystal the frequency decreases. If the film is thin and rigid the decrease in frequency is proportional to the mass of the film m
Cnf ∆−=∆
1:ligningsSauerbrey`
Paper III
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Paper III
Main results / Conclusions
• Resins dissolved in pure heptane adsorb onto a hydrophilic gold surface (2.3 mg/m3), and pack into a compact monolayer (figure)
• Increased aromatic content in the solvent, decreases the adsorption of resins: 50/50 heptane/toluene → 0.6 mg/m3 and hardly at all in pure toluene
• Studies show that resins are not able to desorb pre-adsorbed asphaltenes from the surface.
• Neither do they show any tendency to adsorb onto the asphaltene-coated surface
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Paper III
Main results / Conclusions
• Asphaltenes dissolved in 50/50 heptane/toluene (4.4 mg/m3) adsorb to a larger extent than the resins
• In pure toluene (7.1 mg/m3) the asphaltenes adsorb as aggregates in multilayers onto the surface (figure)
• A mixture of asphaltene and resins in 50/50 heptane/ toluene show a larger adsorption than only asphaltenes or resins
⇓• Likely that the resins and
asphaltenes adsorb as mixed aggregates
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R-COOH
R-COOH
RCOOH
R-COOH
R-COOH
R-COOH
(RCOO)2Ca
Gas
Oil
Water
Pressure releaseIncreased pH
(RCOO)2Ca
R-COOH
CO2
(RCOO)2Ca
Naphthenate Formation
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Problems with Acidic Crudes
Precipitation of calcium naphthenate
Naphthenic acid corrosion
Emulsion stabilisation
Environmental problems
Lower price for acidic crudes
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Outline of Doctoral Work
Naphthenic Acid Chemistry• Partitioning between oil and water• Dissociation• Micellisation• Interfacial behaviour• Interactions with asphaltenes
Emulsion Stabilisation• Monolayers of naphthenic acids/naphthenates• Electrostatically stabilisation of o/w-emulsions• Stabilisation by combined D-phase (multilayer) and
asphaltene particles
Formation of Calcium Naphthenate• NIR is presented as a method for studying calcium naphthenate precipitation
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NIR measurements of mixtures of asphaltenes and different concentration of a naphthenic acid
-0.030
-0.025
-0.020
-0.015
-0.010
-0.005
0.000
0 200 400 600 800 1000 1200Time [min]
Optica
l densi
ty
0.125 wt%
No additive
1.25 wt%
3.25 wt%
6.25 wt%
12.5 wt%
0.125 wt% asphaltenes
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NIR measurements for 1.25 wt% of various naphthenic acids in asphaltene mixture
-0.030
-0.025
-0.020
-0.015
-0.010
-0.005
0.000
0 200 400 600 800 1000 1200Time [min]
Optica
l densi
ty
No additive
Fluka
North Sea
C42
CHOL
2C4
Inhibitor A
CNA
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Critical Electric Field Emulsion Stability Cell
0
0.5
1
1.5
2
2.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7Electric field [kV/cm]
Cur
rent
[mA
]Crude oil 3, WC 30%
I
II I II
ECrit
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L1 MicellesE Hexagonal LCD Lamellar LC L2 Reversed micellesF? Reversed
hexagonal LC
[LC = Liquid Crystal]
70°C
Phase diagram ”water–palmetic acid-sodium palmetate”
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Emulsion Stability9.8 ml (55.7wt%) n-decane4.2 ml (32.7wt%) water1.5 g (11.7wt%) [ Palmetic acid D-phase + asphaltenes ]
70°C
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 0.2 0.4 0.6 0.8 1
Asphaltene to modified D-phase ratio
Ecr
itic
al [
kVcm
-1]
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Method
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
1100 1300 1500 1700 1900 2100
Wavelength [nm]
Optica
l D
ensi
ty
Naphthenic acids dissolved in water; pH=11.5
Solution of CaCl2 added
Formation and growth of calcium naphthenate particles monitored with near infrared spectroscopy
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Formation of Calcium Naphthenate
0
0.1
0.2
0.3
0.4
0.5
0 10 20 30 40 50
Time [min]
OD
0.5
[Ca2+]=2.30E-2M [1a1C4]=1.56E-3M
[Ca2+]=2.10E-2M [1a1C4]=1.56E-3M
[Ca2+]=1.80E-2M [1a1C4]=1.56E-3M
[Ca2+]=1.80E-2M [1a1C4]=1.25E-3M
VODrOD ∝⇒∝ 6
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Solubility Products
1.0E-15
1.0E-14
1.0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
160 180 200 220 240 260 280 300MW [g/mol]
Ksp
[M
3]
C18
C18*C16
C7a1
C51
a1C4
a1C4C51
1a1C4
C7a1
1a1C4
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FLUCHA II - Deliverables
Academic3 PhD Thesis4 MSc Thesis27 Refereed articles3 miscellaneous articles (without refereeing)1 edited textbooks ~25 presentations at national/international meetings in addition to the biannual reference group meetings
IndustrialHP DVMHP Instrumentation
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The Life after FLUCHA II
Harald Kallevik Statoil
Øystein Sæther Det Norske Veritas
Gisle Øye Ugelstad Laboratory
Inge Harald Auflem Statoil
Narve Aske Esso Norge
Trond Erik Havre Champion Servo
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Spin-off
Joint Industrial Programme Particle-stabilized emulsions/Heavy crude oils, 2003-2006• ABB • ChevronTexaco • Norsk Hydro • Statoil• BP • Petrobras • TotalFinaElf
Ugelstad LaboratoryFounding Members:• ABB • Champion Servo • ChevronTexaco • IFE• PFI • Norsk Hydro • TotalFinaElf • Statoil
Affiliated Members:• Akzo Nobel • Borregaard Lignotech • ScanWafer • SINTEF Energy Research• KSV • Technical University of Denmark
FLUCHA IIThank you for your attention
Aknowledgements:
- All the post docs and PhD candidates involved in the programme- All industrial sponsors; ABB, Norsk Hydro, Statoil and TotalFinaElf- The Research Council of Norway (NFR)- Statoil R&D Centre in Trondheim for access to the high pressure
instrumentation