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Challenges of Desalting Canadian Crudes Gary W. Sams Director R&D
99% Oil 1% Water
Heavy Oil PFD • Smallest Smallest water water drops drops • Mostly Mostly emulsifi emulsified ed • Solids Solids stabiliz stabilized ed
Treater
90% Oil 10% Water
9% Water
Gas Separator 72% Oil 28% Water Gas FWKO 25% Oil 75% Water
• Smaller Smaller water water drops drops • Shifted Shifted to oil external external 20% Water
• Oil lighter lighter than than water water • High inlet inlet water water cut cut • Oil internal internal • Temperature Temperatures s < 143 C 65% Water Crude Oil Quality Association
Degassing / Dehydration Gas
Dual Frequency Oil
Collector
Inlet Electrodes
HiFlo Spreader
Water
Water
Crude Oil Quality Association
Cyclonic Gas Removal
Crude Oil Quality Association
Desalter Design Issues 2
Settling Rate
K( w o ) gd
T em p e ra t u r e v s V is c o s i ty .
r s o t c a F g n y i f i s l E m u
S Water Solubility t o k e ’ s E c L a w
d
e n t m t a e r a l T c i m e h C P r o g r a m 2 6
F coalescing
KE r 4
d
Crude Oil Quality Association
Solids & Oil in Effluent Small micron particulates, crystalline salt, and heavy solids loads
Substantial asphaltene precipitation Crude Oil Quality Association
Reverse Emulsion 16 API SAGD DilBit
Crude Oil Quality Association
Water Droplet Growth Initial Droplet Distribution
%50 , n o i t 40 a l u 30 p o P20 t e l p10 o r D 0
Final Droplet Distribution
0
50 100 150 200 250 300 350 400 450 500 550 600
Droplet Diameter, microns Crude Oil Quality Association
Demulsifier Selection Kuwait Oil - 25ºAPI
Bottle Test
Electrostatic Bench Test
Water in Oil % By Difference
BS&W Measured %
3.6
1.4
Brand B
4.0
1.51
Brand C
4.8
1.51
Brand D
5.5
Chemical Brand A
Best Performance
0.7
Best Performance
Based on lab tests – Initial BS&W – 10% Crude Oil Quality Association
Electrostatic Field Selection Our Choices Include… • AC – Conventional & Deep-Field • DC Only (with refined products) • Dual Polarity ® - Combination AC/DC • Modulated Dual Polarity ® • Electro-Dynamic Desalting ® • Dual Frequency ® Crude Oil Quality Association
AC Electrostatic Forces Positive Forces & Velocities Electrostatic Voltage Field, V/ m Drag Force
1 # e d o r t c e l E
Drop Velocity
Dipole Force Drop Spacing, S
Droplet Weight, WD
Vertical oil velocity, vv
Droplet Radius, r
2 # e d o r t c e l E
Negative Forces & Velocities Crude Oil Quality Association
DC Electrostatic Forces Positive Forces & Velocities Electrostatic Voltage Field, V/ m Drag Force
1 # e d o r t c e l E
Drop Velocity
Electrophoresis Force
Drop Spacing, S
Droplet Weight, WD
Vertical oil velocity, vv
Droplet Radius, r
2 # e d o r t c e l E
Negative Forces & Velocities Crude Oil Quality Association
Gradient Electrostatic Forces Positive Forces & Velocities
Di-electrophoresis Force Electrostatic Voltage Field, V/ m Drag Force
1 # e d o r t c e l E
Drop Velocity
Drop Spacing, S
Droplet Weight, WD
Droplet Radius, r
Vertical oil velocity, vv
Di-electrophoresis Force
2 # e d o r t c e l E
Negative Forces & Velocities Crude Oil Quality Association
Net Electrostatic Forces Positive Forces & Velocities Di-electrophoresis Force
1 # e d o r t c e l E
Negative Forces & Velocities
Electrostatic Voltage Field, V/ m Drag Force Electrophoresis Force Dipole Force Drop Droplet Velocity Radius, r Drop Spacing, S Droplet Weight, WD
Vertical oil velocity, vv
2 # e d o r t c e l E
Di-electrophoresis Force
Crude Oil Quality Association
Electrostatic Coalescence Net Drop Forces in Voltage Field Viscous Drag + s t l o V
Electrophoretic Force
- V -
-
+ Dipolar Attraction
Weight Dipole
Voltage Field
Direction
+
o l t s
Electrophoretic Force
Direction
Force
Alternating Current
Oscillates
0.4 weight
Reverses
Net is zero
Direct Current
Constant
0.4 weight
Constant
7230 weight Crude Oil Quality Association
AC/DC Electrostatic Field
x u l F l i O
}
Bulk Water Removal
Crude Oil Quality Association
Desalter Hydraulic Efficiency
Crude Oil Quality Association
Excessive Oil Conductivity 1800 1600 m1400 / S n 1200 , y t i 1000 v i t 800 c u d 600 n o 400 C
Typical High
200 0 50
100
150
200
250
300
Temperature, F Crude Oil Quality Association
Heavy Oil Dehydrator Performance Ref: SPE Paper 97786 1 Solid Curves Predicted by Electrostatic
Oil API – 21 TAN - 4
0.9
) 0.8 % ( W0.7 & S0.6 B t 0.5 e l t u 0.4 O
Dehydrator Computer Model
Dual Dual Polarity Frequency
AC
Field AC Dehydrator @ 239 F
0.3
AC Dehydrator @ 219F
Modulated Dual Polarity
0.2 0.1
AC/DC @ 218F Modulated AC/DC @ 220F Bimodal AC/DC @ 220F
0 0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
Oil Flux (bopd/sf) Crude Oil Quality Association
Technology Retrofit A Commercial Installation
Gravity = 12ºAPI Technology: Temperature: Oil Flow: Outlet BS&W:
Before Retrofit* Dual Polarity 220ºF 4000 BOPD 1%
After Retrofit* Dual Frequency 200ºF 9200 BOPD 0.1%
*Data is per vessel. There are four vessels. Crude Oil Quality Association
SAGD -Dilbit Desalting Pilot Results Process Parameters: Dilbit API: 16 ,
Temp: 280F,
Flux: 70 bopd/ft2
Feed
Outlet
Stage Tech. BS&W, % Salt, ppm Cl- BS&W, % Salt, ppm Cl1
AC
5.8
Wash Water: 5 % 2
DF
0.4
220 Recycle: 5 % 6
0.4
6
Valve DP: 10 psi 0.35
1
Mixing Efficiency = 25% Crude Oil Quality Association
Desalter Technology Comparison Inlet Salt
Outlet Salt
BSW
AC
258
41
0.5
AC‐ pAC
258
12
0.4
DF
211
6.3
0.4
EDD‐ EDD
200
3.2
0.4
DF‐DF 210
2.8
0.3
200
2.4
0.3
210
2
0.4
EDD‐ DF DF‐ EDD
Crude Oil Quality Association
Conclusions Heavy Canadian crudes pose unique challenges: • High Oil Conductivities • Asphaltene Precipitation • High Solids Loading • Reverse Emulsions • Increased Interface Rag • Poor Effluent Water Quality
Crude Oil Quality Association
