8

Pipeline Emulsion Transportation for

Heavy Oils
D . P. Rimmer , A. A. Gregoli, J. A. Hamshar, and E . Yildirim
☼
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Canadian Occidental Petroleum, L t d . , 1500, 635 8th Avenue, S.W.,

Calgary, Alberta, Canada T2P 3Z1
Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

Oil-in-water emulsions provide a cost-effective alternative to heated

pipelines or diluents for transportation of heavy crude oil or bitumen.
A typical “transport emulsion” is composed of 70% crude oil, 30%
aqueous phase, and 500-2000 ppm of a stabilizing surfactant for-
mulation. The resulting emulsion has a viscosity in the 50—200-cP
range at pipeline operating conditions. Nonionic surfactants have the
advantage of relative insensitivity to the salt content of the aqueous
phase. The ethoxylated alkylphenol family of surfactants has been
used successfully for the formation of stable emulsions that resist
inversion. Correlations have been developed for prediction of emul-
sion viscosity as a function of emulsion life and process conditions.
The cost of stabilizing surfactants is estimated at $0.50 to $1.00 per
barrel of crude oil for a transportation distance of200 to 400 miles.

ÏJONS OR DISPERSIONS O F HEAVY C R U D E OIL i n water o r b r i n e have b e e n

u s e d i n several parts o f the w o r l d f o r p i p e l i n e transportation o f b o t h waxy
a n d heavy asphaltic-type c r u d e oils. T h e h y d r o d y n a m i c a l l y s t a b i l i z e d d i s p e r ­
sion transportation c o n c e p t is d e s c r i b e d b y the S h e l l O i l C o r p o r a t i o n c o r e
f l o w t e c h n o l o g y (1). T h e use o f surfactants a n d w a t e r to f o r m o i l - i n - w a t e r
emulsions w i t h c r u d e oils is t h e subject o f a l o n g series o f patents a n d was
p r o p o s e d f o r use i n t r a n s p o r t i n g P r u d h o e B a y c r u d e o i l (2). F u r t h e r m o r e ,
surfactants m a y b e i n j e c t e d i n t o a w e l l b o r e to effect e m u l s i f i c a t i o n i n t h e
p u m p o r t u b i n g f o r t h e p r o d u c t i o n o f heavy c r u d e oils as o i l - i n - w a t e r e m u l ­
sions (3, 4).

^Corresponding author. Current address: Oxy USA, Inc., Box 3908, Tulsa OK 74102

0065-2393/92/0231-0295 $06.00/0
© 1992 American Chemical Society

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 296 EMULSIONS IN THE PETROLEUM INDUSTRY

T h e use o f o i l - i n - w a t e r e m u l s i o n s to r e d u c e the viscosity o f heavy c r u d e

oils a n d b i t u m e n s a n d thus p e r m i t t h e i r transportation b y c o n v e n t i o n a l
p i p e l i n e has b e e n u n d e r d e v e l o p m e n t b y C a n a d i a n O c c i d e n t a l since the f a l l
o f 1984. T h e benefits o f these e m u l s i o n s m a y be a p p l i e d to p i p e l i n e trans­
p o r t a t i o n , to the c o m b u s t i o n o f heavy fuels, to increase the p r o d u c t i o n rates
o f h e a v y - c r u d e - o i l w e l l s , a n d to i m p r o v e secondary r e c o v e r y o f heavy c r u d e
o i l a n d b i t u m e n . I n this c h a p t e r , the emphasis is o n d i s c u s s i o n o f the g e n e r a l
characteristics o f o i l - i n - w a t e r e m u l s i o n s as r e l a t e d to t h e i r a p p l i c a t i o n for
p i p e l i n e t r a n s p o r t a t i o n . T h e i n c e n t i v e f o r d e v e l o p i n g this t e c h n o l o g y is to
p r o v i d e an alternative to the use o f d i l u e n t s o r the a p p l i c a t i o n o f heat f o r
viscosity r e d u c t i o n i n p i p e l i n e s f o r heavy c r u d e o i l . T h e viscosity range for
o i l - i n - w a t e r e m u l s i o n s as c o m p a r e d to u n d i l u t e d heavy c r u d e oils a n d b i t u ­
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m e n s is i l l u s t r a t e d i n F i g u r e 1. A l s o i n d i c a t e d i n the figure is the viscosity

Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

specification f o r t y p i c a l p i p e l i n e s f o r heavy c r u d e o i l . A s n o t e d , the e m u l s i o n

viscosity is w e l l b e l o w the r e q u i r e d l e v e l a n d p r o v i d e s o p e r a t i n g benefits
c o m p a r e d to n o r m a l operations i n w h i c h viscosity r e d u c t i o n is a c h i e v e d b y
use o f d i l u e n t s .
T h e use o f o i l - i n - w a t e r e m u l s i o n s i n m a j o r p i p e l i n e systems represents a

100, 000

10, 000
CL

1. 000
ω
ο , OPERATING RANGE
ω l
F O R HEAVY
ω C R U D E OIL

100
OIL-IN-WATER E M U L S I O N S

10
40 60 80 100 120 140 160
Temperature, deg. F
Figure 1. Reduction of viscosities of heavy crude oils and bitumens by conver­
sion to oil-in-water emulsions.

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 8. RIMMERETAL. Pipeline Emulsion Transportation for Heavy Oils 297

r a d i c a l d e p a r t u r e f r o m c o n v e n t i o n a l p r a c t i c e . A s a result, a n u m b e r o f pos­
sibilities are causes f o r c o n c e r n , i n c l u d i n g the p o s s i b i l i t y o f f r e e z i n g , c o r r o ­
s i o n , e m u l s i o n separation o r i n v e r s i o n , c u s t o d y transfer, w a t e r separation,
and t r e a t m e n t . S u c h issues m a y b e satisfactorily h a n d l e d a n d w i l l b e dis­
cussed.
O i l - i r i - w a t e r e m u l s i o n s f o r p i p e l i n e t r a n s p o r t a t i o n o f heavy c r u d e oils
m a y b e c o n s i d e r e d a d e v e l o p i n g t e c h n o l o g y that is not yet i n w i d e c o m m e r ­
c i a l use. Several c o m p a n i e s have o n g o i n g p r o g r a m s i n this area a n d are
c o m p e t i n g i n m a r k e t i n g o f the processes a n d the surfactant f o r m u l a t i o n s
i n v o l v e d . T h e r e f o r e , m u c h o f the i n f o r m a t i o n r e l a t i n g to this t e c h n o l o g y is
c o n f i d e n t i a l . I n this chapter, the t o p i c is d i s c u s s e d o n the basis o f o u r
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experience i n d e v e l o p m e n t a n d testing o f the e m u l s i o n transportation t e c h ­

nology.
Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

C a n a d i a n O c c i d e n t a l ' s interest i n o i l - i n - w a t e r e m u l s i o n s is r e l a t e d to
m a r k e t i n g a n d transportation o f A t h a b a s c a b i t u m e n a n d heavy A l b e r t a c r u d e
oils. A laboratory a n d p i l o t - p l a n t d e v e l o p m e n t p r o g r a m was i n i t i a t e d i n late
1984 at the O c c i d e n t a l C e n t e r ( f o r m e r l y the C i t i e s Service T e c h n o l o g y
C e n t e r ) i n T u l s a , O k l a h o m a . T h e p r o g r a m has i n c l u d e d the f o l l o w i n g fea­
tures:

• d e v e l o p m e n t o f surfactant systems f o r p r e p a r a t i o n o f stable

oil-in-water emulsions
• e v a l u a t i o n o f e m u l s i o n p r e p a r a t i o n systems a n d selection o f
optimal conditions for continuous-emulsion preparation

• d e v e l o p m e n t o f laboratory tests for evaluating the stability a n d

p i p e l i n i n g life o f o i l - i n - w a t e r e m u l s i o n s
• c o n s t r u c t i o n o f an e m u l s i o n p i l o t p l a n t a n d testing o f the
r h e o l o g i c a l p r o p e r t i e s a n d p i p e l i n e stability o f o i l - i n - w a t e r
emulsions

• c o m p l e t i o n o f t w o field tests to demonstrate the t e c h n o l o g y

Process Design and Operation

E m u l s i o n s d e s i g n e d f o r p i p e l i n e t r a n s p o r t a t i o n are c o m p o s e d o f a c o n t i n u ­
ous phase c o n s i s t i n g o f w a t e r o r b r i n e , d r o p l e t s o f the heavy c r u d e o i l to b e
t r a n s p o r t e d , a n d additives g e n e r a l l y c o n s i s t i n g o f c h e m i c a l surfactants. T h e
p u r p o s e o f the surfactants is to p r o v i d e sufficient stability to the h y d r o c a r ­
b o n d r o p l e t s so that they d o not coalesce o r absorb w a t e r o r b r i n e d u r i n g the
p i p e l i n i n g o p e r a t i o n . T h e aqueous phase t y p i c a l l y c o m p r i s e s a p p r o x i m a t e l y
2 5 - 3 5 w t % o f the total e m u l s i o n , a n d the actual c o n c e n t r a t i o n is selected so
that the m i n i m u m q u a n t i t y o f w a t e r is u s e d w h i l e m e e t i n g d e s i r e d viscosity
specifications. T h e p r i n c i p a l c o m p o n e n t s o f an e m u l s i o n p i p e l i n e system are
i l l u s t r a t e d i n F i g u r e 2. A s the figure indicates, the system is relatively s i m p l e

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 298 EMULSIONS IN THE PETROLEUM INDUSTRY

HEAVY CRUDE MIXER EMULSION

STORAGE

WATER

SURFACTANT
PIPELINE SYSTEM
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Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

DRY CRUDE

WATER
EMULSION
TREATING

Figure 2. Facilities required for a heavy-crude-oil emulsion transportation

system.

a n d does not r e q u i r e extensive m o d i f i c a t i o n s to the p i p e l i n e system itself.

T h e p r i n c i p a l steps i n c l u d e d i n o p e r a t i o n o f a transport e m u l s i o n system
i n c l u d e p r e p a r a t i o n o f the o i l - i n - w a t e r e m u l s i o n , storage a n d p u m p i n g o f
the e m u l s i o n , a n d finally b r e a k i n g o f the e m u l s i o n f o r r e c o v e r y o f the d r y
heavy c r u d e o i l . T h e details i n v o l v e d i n each phase o f the o p e r a t i o n are
d i s c u s s e d i n the f o l l o w i n g sections.

Emulsion Preparation. P r e p a r i n g a transport e m u l s i o n is a f u n d a ­

m e n t a l l y s i m p l e o p e r a t i o n that i n c l u d e s the steps o f f o r m i n g a w a t e r - b r i n e
s o l u t i o n o f the e m u l s i o n - s t a b i l i z i n g c o m p o s i t i o n f o l l o w e d b y a s h e a r i n g p r o ­
cess i n w h i c h the c r u d e o i l a n d aqueous phases are m e t e r e d to a specific
mixing device.
E a c h d e v e l o p e r o f transport e m u l s i o n t e c h n o l o g y selects specific surfac­
tant f o r m u l a t i o n s f o r p a r t i c u l a r applications. T h e p r i m a r y f u n c t i o n s o f the
surfactant are to r e d u c e the i n t e r f a c i a l t e n s i o n b e t w e e n the c r u d e o i l a n d
aqueous phases, to p r o v i d e stability to the i n d i v i d u a l o i l droplets f o r m e d
d u r i n g the s h e a r i n g process, a n d to p r e v e n t subsequent coalescence o f the
d r o p l e t s . T h e surfactant m o l e c u l e s collect at the phase b o u n d a r i e s a n d
p r o v i d e resistance to coalescence o f the o i l droplets b y establishing m e c h a n ­
i c a l , steric, a n d e l e c t r i c a l barriers (5).

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 8. RIMMER ET AL. Pipeline Emulsion Transportation for Heavy Oils 299

A w i d e range o f surfactant types m a y b e u s e d to f o r m a n d stabilize

transport e m u l s i o n s . N o n i o n i c surfactants have the advantage o f relative
insensitivity to the salt content o f the aqueous phase b e i n g e m p l o y e d (6).
T h e g r o u p o f surfactants k n o w n as ethoxylated a l k y l p h e n o l s , r e p r e s e n t e d b y
the f o r m u l a ,

R-C H -(CH CH -0)-H

6 4 2 2

w h e r e R c a n be any h y d r o c a r b o n a n d χ is the n u m b e r o f ethylene oxide u n i t s ,

is p a r t i c u l a r l y u s e f u l i n the f o r m a t i o n a n d t r a n s p o r t a t i o n o f h e a v y - c r u d e - o i l
emulsions.
W h a t e v e r the specific f o r m u l a t i o n u s e d , the final c o n c e n t r a t i o n o f the
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surfactant is selected o n the basis o f the characteristics o f the h e a v y - c r u d e -

Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

o i l - b r i n e system a n d the c o n d i t i o n s to w h i c h the e m u l s i o n w i l l b e subjected.

T h e p r i n c i p a l factor i n f l u e n c i n g the q u a n t i t y o f surfactant r e q u i r e d is the
l e n g t h o f the p i p e l i n e system i n w h i c h the e m u l s i o n w i l l be p u m p e d . T h e
c o n c e n t r a t i o n o f surfactant b a s e d o n the total e m u l s i o n may range f r o m 200
to 5 0 0 0 p p m , d e p e n d i n g o n specific system characteristics.
M a j o r e q u i p m e n t r e q u i r e d f o r p r e p a r a t i o n o f transport e m u l s i o n s i n ­
cludes h e a t e d tankage f o r c r u d e o i l a n d b r i n e ; i n j e c t i o n p u m p s f o r c r u d e o i l ,
b r i n e , a n d surfactant; p r e m i x i n g a n d m i x i n g devices; a n d e m u l s i o n storage
tanks. M i n i m a l i n s t r u m e n t a t i o n is also r e q u i r e d to m o n i t o r flow rates a n d
t e m p e r a t u r e s . T h e basic m e t h o d f o r e m u l s i o n p r e p a r a t i o n is to heat the
c r u d e o i l a n d b r i n e solutions to the d e s i r e d o p e r a t i n g t e m p e r a t u r e , dissolve
the surfactant i n t o the b r i n e , a n d s i m u l t a n e o u s l y p u m p the c r u d e o i l a n d
b r i n e t h r o u g h a m i x i n g d e v i c e i n the d e s i r e d p r o p o r t i o n s . T y p i c a l e m u l s i o n
f o r m a t i o n temperatures are i n the 5 0 - 9 0 °C range.
C r u d e o i l a n d b r i n e p u m p s m a y b e c e n t r i f u g a l o r positive d i s p l a c e m e n t ,
b u t must b e capable o f p r o v i d i n g steady flow to the m i x i n g device because
e m u l s i o n p r o p e r t i e s are h i g h l y d e p e n d e n t o n the r e s u l t i n g c r u d e - o i l - b r i n e
ratio. Surfactant m a y be d i s s o l v e d i n the b r i n e phase o n a b a t c h o r c o n t i n u ­
ous basis. Static mixers p r o v i d e a s i m p l e m e t h o d for the p r e p a r a t i o n step
because they r e q u i r e n o m o v i n g parts, are easy to scale u p , a n d p r o v i d e an
m i x i n g intensity that is s u i t e d to p r e p a r a t i o n o f transport e m u l s i o n s .
T h e t e c h n i q u e s u s e d i n the p r e p a r a t i o n o f a stable o i l - i n - w a t e r e m u l s i o n
f o r p i p e l i n e transportation are i l l u s t r a t e d b y the results o f a field test i n
w h i c h an A t h a b a s c a b i t u m e n was e m u l s i f i e d a n d p u m p e d t h r o u g h a 3 - i n . x
4000-ft. p i p e - l o o p system f o r a total distance o f a p p r o x i m a t e l y 500 m i l e s .
T h e e m u l s i o n i n this case c o m p r i s e d 7 5 % b y w e i g h t o f the 8.3° A P I b i t u m e n
a n d 2 5 % o f a synthetic b r i n e c o n t a i n i n g 1.7% N a C l . ( A P I gravity is d e f i n e d
i n the Glossary.) T h e surfactant u s e d was a m i x t u r e o f t w o ethoxylated
n o n y l p h e n o l surfactants; the first c o m p o n e n t c o n t a i n e d an average o f 40
ethylene oxide units p e r m o l e c u l e , a n d the s e c o n d c o m p o n e n t c o n t a i n e d 100
units. A p p r o x i m a t e l y 1500 p p m o f the surfactant m i x t u r e , b a s e d o n the total

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 300 EMULSIONS IN THE PETROLEUM INDUSTRY

e m u l s i o n , was u s e d i n p r e p a r a t i o n o f t h e e m u l s i o n . T h e e m u l s i o n was
f o r m e d b y h e a t i n g b o t h t h e b r i n e a n d b i t u m e n t o 180 ° F a n d p u m p i n g t h e
c o m b i n e d streams t h r o u g h a 2 - i n . static m i x e r at a rate o f about 10 ft/s. T h i s
o p e r a t i o n p r o d u c e d a n e m u l s i o n w i t h a n average d r o p l e t d i a m e t e r o f 2 7 μπι
a n d a viscosity near 120 c P at a m b i e n t c o n d i t i o n s . T h e e m u l s i o n was i n t r o ­
d u c e d d i r e c t l y i n t o t h e p i p e - l o o p system f o r r h e o l o g y a n d stability testing
a n d was stable t h r o u g h o u t t h e o p e r a t i n g test p e r i o d o f a p p r o x i m a t e l y 1
week.

E m u l s i o n P i p e l i n e O p e r a t i o n s . P r e d i c t i o n o f p i p e l i n e pressure
gradients is r e q u i r e d f o r o p e r a t i o n o f any p i p e l i n e system. Pressure g r a d i ­
ents f o r a transport e m u l s i o n flowing i n c o m m e r c i a l - s i z e p i p e l i n e s m a y b e
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e s t i m a t e d v i a standard t e c h n i q u e s because c h e m i c a l l y s t a b i l i z e d e m u l s i o n s
Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

e x h i b i t r h e o l o g i c a l b e h a v i o r that is n e a r l y N e w t o n i a n . T h e e m u l s i o n viscos­
ity must b e k n o w n t o i m p l e m e n t these m e t h o d s . T h e best w a y t o d e t e r m i n e
e m u l s i o n viscosity f o r an a p p l i c a t i o n is to p r e p a r e a n e m u l s i o n b a t c h c o n ­
f o r m i n g to p l a n n e d specifications a n d d i r e c t l y measure t h e p i p e viscosity i n a
p i p e l o o p o f at least 1-in. i n s i d e d i a m e t e r . C a r e must b e taken t o use t h e
same b r i n e c o m p o s i t i o n , surfactant c o n c e n t r a t i o n , d r o p l e t size d i s t r i b u t i o n ,
b r i n e - c r u d e - o i l ratio, a n d t e m p e r a t u r e as are e x p e c t e d i n t h e field a p p l i c a ­
t i o n . I n p r a c t i c e , a p i l o t - p l a n t r u n m a y not b e feasible, o r there may b e some
d i s p a r i t y b e t w e e n p i p e - l o o p test c o n d i t i o n s a n d a n t i c i p a t e d c o m m e r c i a l
p i p e l i n e c o n d i t i o n s . I n these cases, adjustments m a y b e a p p l i e d t o t h e best
available viscosity data u s i n g adjustment factors d e s c r i b e d later t o c o m p e n ­
sate f o r disparities i n o p e r a t i n g parameters b e t w e e n t h e m e a s u r e m e n t c o n ­
ditions a n d t h e p i p e l i n e c o n d i t i o n s .
A f t e r t h e e m u l s i o n viscosity is estimated, f r i c t i o n factor charts m a y b e
u s e d d i r e c t l y t o d e t e r m i n e t h e flow r e g i m e ( l a m i n a r o r t u r b u l e n t ) a n d t h e
pressure gradient. E m u l s i o n viscosity m a y b e u s e d as a n i n p u t t o a s t a n d a r d
p i p e l i n e m o d e l . N e v e r t h e l e s s , i t is strongly r e c o m m e n d e d that p i l o t - p l a n t
testing b e c o m p l e t e d o n n e w c r u d e oils b e f o r e c o m m e r c i a l a p p l i c a t i o n .
D i r e c t m e a s u r e m e n t o f e m u l s i o n viscosity at p i p e l i n e c o n d i t i o n s is rec­
o m m e n d e d , especially i f l a m i n a r flow o p e r a t i o n is e x p e c t e d . V i s c o s i t y is o f
lesser significance i n t u r b u l e n t flow.
F o r p r a c t i c a l p u r p o s e s , e m u l s i o n viscosities m a y b e adjusted f o r v a r i a ­
tions i n t e m p e r a t u r e , w a t e r content, a n d d r o p l e t size d i s t r i b u t i o n a c c o r d i n g
to a sensitivity f o r m u l a o f t h e f o l l o w i n g t y p e :

WAF 2 PSAF 2
μ = μι(ΎΑ¥) (1)
i PSAFi J
[ WAFj J
w h e r e μ is e m u l s i o n viscosity (in c P ; 1 c P = 0.001 P a s ) , T A F is t h e adjusting
factor f o r t e m p e r a t u r e d i f f e r e n c e , W A F is t h e adjusting factor f o r w a t e r
content, P S A F is t h e adjusting factor f o r d r o p l e t size, subscript 1 refers t o
c o n d i t i o n s at w h i c h viscosity is k n o w n , a n d subscript 2 refers t o c o n d i t i o n s o f

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 8. RIMMERETAL. Pipeline Emulsion Transportation for Heavy Oils 301

a p p l i c a t i o n . T h i s f o r m u l a m a y be u s e d for field applications i n w h i c h the

viscosity is k n o w n f r o m e x p e r i m e n t s , b u t it m u s t be adjusted to actual
conditions.
T h e adjustment factor for t e m p e r a t u r e is b a s e d o n a t e m p e r a t u r e d i f f e r ­
ence, ( T - 2\). I f the t e m p e r a t u r e d i f f e r e n c e is negative, t h e n T A F > 1, a n d
2

the inverse o f the T A F f r o m the correlations must be u s e d .

T h e t e m p e r a t u r e sensitivity o f e m u l s i o n viscosity m a y be d e s c r i b e d as a
p e r c e n t a g e change i n viscosity p e r u n i t t e m p e r a t u r e change. T h e t e m p e r a ­
t u r e - a d j u s t i n g factor varies f o r d i f f e r e n t e m u l s i o n s , d e p e n d i n g o n the base
c r u d e - o i l content, b r i n e content, surfactant, a n d o t h e r variables a n d gener­
ally ranges f r o m about 1.8 to 3.6 cP/°C. (The v a r i a t i o n i n the viscosity o f
w a t e r w i t h t e m p e r a t u r e is a p p r o x i m a t e l y 2.2 cP/°C.)
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T o a p p l y this factor, the percentage viscosity change must b e c o m ­

Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

p o u n d e d , as w i t h interest rates. F o r example, a c o r r e c t i o n o f 20 °C b a s e d o n

a factor o f 2 . 5 % p e r °C w o u l d b e c a l c u l a t e d as f o l l o w s :

T A F = — L — = 0.61 (2)
1.025 20

A g e d emulsions c o n t a i n i n g a substantial p o r t i o n o f large (>200 μπι) droplets

e x h i b i t a l o w e r t e m p e r a t u r e - v i s c o s i t y sensitivity, a n d this effect m u s t b e
c o n s i d e r e d i n c a l c u l a t i n g pressure gradients. A d j u s t m e n t factors s h o w n are
f o r t e m p e r a t u r e increases (lower viscosity). T h e inverse o f the factor applies
to t e m p e r a t u r e decreases (higher viscosity).
T h e viscosity o f an o i l - i n - w a t e r e m u l s i o n is sharply d e p e n d e n t o n w a t e r
content. V i s c o s i t y adjustment factors f o r w a t e r content may be o b t a i n e d
f r o m a c o r r e l a t i o n s u c h as that s h o w n i n F i g u r e 3. I n this figure, the adjust­
m e n t factor is d e f i n e d as 1.0 at the base l e v e l o f 3 0 % water. T h e actual
c o r r e l a t i o n to b e u s e d is d e p e n d e n t o n the base c r u d e - o i l content a n d other
factors.
A p o r t i o n o f the w a t e r i n an e m u l s i o n c a n b e d i s p e r s e d w i t h i n the o i l
d r o p l e t s . T h i s p o r t i o n o f the total w a t e r s h o u l d b e t r e a t e d as o i l w h e n
e s t i m a t i n g e m u l s i o n viscosity. G e n e r a l l y , a d d e d w a t e r is present i n the c o n ­
t i n u o u s phase. I f the c r u d e o i l contains w a t e r p r i o r to e m u l s i o n f o r m a t i o n ,
this w a t e r m a y be present i n e i t h e r the c o n t i n u o u s (water) phase o r the
d i s p e r s e d (oil) phase after e m u l s i o n f o r m a t i o n , d e p e n d i n g p r i m a r i l y o n the
w a t e r d r o p l e t size i n the c r u d e o i l . I n o r d e r to p r e d i c t h o w m u c h o f the w a t e r
i n the c r u d e o i l w i l l b e f r e e d i n t o the c o n t i n u o u s phase, e m u l s i o n p r e p a r a ­
t i o n experiments w i t h the actual c r u d e o i l to b e u s e d are necessary.
V i s c o s i t y adjustment factors f o r d r o p l e t size d i s t r i b u t i o n m a y b e deter­
m i n e d b y a c o r r e l a t i o n s u c h as that s h o w n i n F i g u r e 4. M e a n d r o p l e t size is
d e f i n e d o n a v o l u m e basis. D i s p e r s i t y is an i n d e x o f wideness o f the d r o p l e t
size d i s t r i b u t i o n . It is d e f i n e d for this p u r p o s e as the ratio o f v o l u m e - m e a n
d r o p l e t size to p o p u l a t i o n - m e a n d r o p l e t size.
A s an e m u l s i o n ages, d r o p l e t coalescence occurs a n d leads to i n c r e a s e d

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 302 EMULSIONS IN THE PETROLEUM INDUSTRY
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Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

ι • ι ι ι » • t
25 30 35 40 45
WATER CONTENT OF EMULSION, WT%

Figure 3. Viscosity adjustment factors for water content variations based on

emulsions containing 30% water.

Figure 4. Viscosity adjustment factors for droplet size distribution based on

viscosity at 30-^m mean droplet size and dispersity of 3.0.

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 8. RIMMERETAL. Pipeline Emulsion Transportation for Heavy Oils 303

d r o p l e t size a n d dispersity. T h e s e increases, i n t u r n , cause r e d u c e d e m u l s i o n

viscosity. E m u l s i o n viscosity m a y be r e l a t e d d i r e c t l y to a g i n g b y an e q u a t i o n
o f the f o r m :

μ = μ exp (-fc0)
0 (3)

w h e r e μ is the viscosity (subscript 0 indicates i n i t i a l viscosity), θ is the t i m e

o f e m u l s i o n transport, a n d k is a constant c h a r a c t e r i z i n g the e m u l s i o n d e g ­
r a d a t i o n rate. T h i s e q u a t i o n c a n also b e w r i t t e n i n terms o f distance t r a v e l e d
rather t h a n t i m e o f transport.
T h e value o f k m a y be m e a s u r e d e x p e r i m e n t a l l y f o r a g i v e n e m u l s i o n .
T h e e m u l s i o n d e g r a d a t i o n rate decreases as p i p e d i a m e t e r increases. A
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conservative a s s u m p t i o n f o r c a l c u l a t i o n o f viscosities f o r p i p e l i n e d e s i g n is
Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

that the d e g r a d a t i o n rate is p r o p o r t i o n a l to the s u r f a c e - t o - v o l u m e ratio (1/d),

w h e r e d is the p i p e d i a m e t e r .
E m u l s i o n aging rates increase w i t h t e m p e r a t u r e . A g i n g rates i n t u r b u ­
lent flow appear to b e c o m e arrested after a c e r t a i n p o i n t , generally b e i n g
less t h a n the rates o b s e r v e d i n l a m i n a r flow. A g i n g rates are s u p p r e s s e d b y
i n c r e a s e d surfactant c o n c e n t r a t i o n as a result o f the anticoalescence action
o f the surfactant.
T h e viscosity o f an o i l - i n - w a t e r e m u l s i o n generally varies i n p r o p o r t i o n
to the c o n t i n u o u s - p h a s e viscosity. I f c o n c e n t r a t e d b r i n e s or b r i n e s c o n t a i n ­
i n g additives are to b e u s e d , t h e n the c o n t i n u o u s - p h a s e viscosity m a y b e
substantially greater t h a n that o f water, a n d a c o r r e c t i o n s h o u l d be a p p l i e d .
Specific adjustment factors f o r this effect m a y be e s t i m a t e d as the ratio o f
viscosities o f the b r i n e s i n the k n o w n a n d u n k n o w n e m u l s i o n s .
T h e surfactant c o n c e n t r a t i o n is n o r m a l l y not h i g h e n o u g h to substan­
tially affect the c o n t i n u o u s - p h a s e viscosity. H o w e v e r , changes i n surfactant
c o n c e n t r a t i o n f o r a p i p e l i n e a p p l i c a t i o n generally cause an i n d i r e c t effect o n
r h e o l o g y b y w a y o f t h e i r effects o n e m u l s i o n p r e p a r a t i o n a n d o n the e m u l ­
sion aging rate. G e n e r a l l y , an increase i n surfactant c o n c e n t r a t i o n results i n
a s m a l l e r i n i t i a l d r o p l e t size a n d s l o w e r e m u l s i o n aging. B o t h o f these c o n d i ­
tions t e n d to increase viscosity.

Monitoring Emulsion Aging. T h e surfactants u s e d i n transport

e m u l s i o n s may g r a d u a l l y lose t h e i r a b i l i t y to stabilize the o i l d r o p l e t s . A s the
o i l droplets coalesce, a two-phase m i x t u r e is f o r m e d , a n d it r e m a i n s
p u m p a b l e w i t h no significant change i n effective viscosity. T h i s process is
r e f e r r e d to as e m u l s i o n f a i l u r e . A n alternative to this process is i n v e r s i o n o f
the e m u l s i o n , i n w h i c h a w a t e r - i n - o i l e m u l s i o n is f o r m e d w i t h a p o t e n t i a l l y
v e r y h i g h viscosity. P r o p e r s e l e c t i o n o f the surfactant f o r m u l a t i o n c a n p r e ­
vent the o c c u r r e n c e o f e m u l s i o n i n v e r s i o n .
Indicators o f e m u l s i o n aging that may be m o n i t o r e d i n c l u d e d r o p l e t size
g r o w t h , viscosity d e c l i n e , surfactant loss, a n d r e d u c t i o n o f shear stability.

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 304 EMULSIONS IN THE PETROLEUM INDUSTRY

D r o p l e t g r o w t h rates a n d viscosity d e c l i n e rates b o t h are e x p o n e n t i a l p r o ­

cesses, f o l l o w i n g a straight l i n e o n a s e m i - l o g p l o t (log μ o r l o g d vs. t i m e ) ,
p

w h e r e d is the m e a n d r o p l e t d i a m e t e r . E m u l s i o n failure is also associated

?

w i t h a c e r t a i n m i n i m u m viscosity, d e p e n d i n g o n w a t e r content, c r u d e - o i l
content, t e m p e r a t u r e , etc. V i s c o s i t y a n d m e a n d r o p l e t size may be p r o j e c t e d
to estimate the t i m e r e m a i n i n g b e f o r e e m u l s i o n f a i l u r e . T h e u l t i m a t e d r o p ­
let size a n d viscosity s h o u l d be d e t e r m i n e d e x p e r i m e n t a l l y f o r the same
formulation i n a pilot-plant pipe loop.
T h e e m u l s i o n surfactant c o n c e n t r a t i o n generally declines g r a d u a l l y as
the e m u l s i o n approaches f a i l u r e , c u l m i n a t i n g i n a s u d d e n sharp d r o p at o r
after the t i m e o f e m u l s i o n f a i l u r e . C h a n g e s o f surfactant c o n c e n t r a t i o n t e n d
to lag b e h i n d changes evident f r o m d r o p l e t size a n d o t h e r indicators, a n d
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this situation makes surfactant c o n c e n t r a t i o n analysis ineffective as an i n d i ­

Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

cator o f a p p r o a c h i n g e m u l s i o n f a i l u r e .
E m u l s i o n l i f e expectancy f o r a f o r m u l a t i o n may be conservatively scaled
u p f r o m 2 - i n . p i p e - l o o p tests at the same v e l o c i t y b y d e m o n s t r a t i n g that the
e m u l s i o n w i l l survive transport f o r the d e s i r e d actual distance i n the p i l o t
p l a n t . P i l o t - p l a n t transport is a m o r e severe test o f e m u l s i o n life than trans­
p o r t i n larger lines. T h e conservative nature o f this scale-up c r i t e r i o n tends
to dictate specification o f some excess surfactant f o r a large-scale a p p l i c a t i o n
b e y o n d the m i n i m u m q u a n t i t y r e q u i r e d .

Effects of Pumps and Valves. T h e flow o f emulsions through

p i p e l i n e p u m p a n d valves c o u l d p o t e n t i a l l y affect the e m u l s i o n p r o p e r t i e s .

Pumps. I m p e l l e r t i p s p e e d is a u s e f u l g u i d e to relate c e n t r i f u g a l
p u m p s i n terms o f the energy they may i m p a r t o n an e m u l s i o n . Several
p u m p s have b e e n tested o n e m u l s i o n service w i t h t i p speeds u p to 200 ft/s,
c o m p a r e d to t y p i c a l p u m p - s t a t i o n applications o f approximately 300 ft/s.
T h e results o f these tests show that e m u l s i o n shear stability is u n c h a n g e d
after several passes t h r o u g h a c e n t r i f u g a l p u m p , t y p i c a l o f multistage p u m p -
station a p p l i c a t i o n . S o m e u n d e r s i z e d m a t e r i a l is f o r m e d at the expense o f
o v e r s i z e d . T h e s e results i n d i c a t e that c o m m e r c i a l p u m p applications s h o u l d
not b e a p r o b l e m . T e s t i n g has b e e n l i m i t e d , h o w e v e r , a n d thus p r i o r to any
c o m m e r c i a l a p p l i c a t i o n , the specific p u m p characteristics s h o u l d be c o m ­
p a r e d against the p u m p s already tested. P u m p tip speeds a n d the p u m p
m o d e l i n g l a w that relates p u m p geometries s h o u l d be r e v i e w e d .
Passage o f e m u l s i o n t h r o u g h a c e n t r i f u g a l p u m p at a b n o r m a l l y l o w rates
a n d at a h i g h b a c k pressure can shorten the e m u l s i o n shear stability. G e a r
p u m p s are low-shear devices a n d d o not adversely affect the e m u l s i o n .

Valves. L i m i t e d laboratory testing shows that emulsions can be let

d o w n across a pressure d i f f e r e n t i a l o f 1000 ψ (6895 k P a ) , t y p i c a l o f c o m m e r -

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 8. RIMMERETAL. Pipeline Emulsion Transportation for Heavy Oils 305

c i a l applications, w i t h m a r g i n a l r e d u c t i o n i n shear stability. V e l o c i t i e s across

the valve p o r t r e a c h e d 130 ft/s (39.6 m/s).

Effects of Pipeline Shutdown and Restart. W h e n a p i p e l i n e

c o n t a i n i n g e m u l s i o n is s t o p p e d a n d a l l o w e d to r e m a i n s h u t - i n for one o r
m o r e days, t h e r e is generally a h i g h e r than n o r m a l pressure gradient o n
restarting flow. I n p i l o t - p l a n t experiments, the pressure gradient substan­
tially r e t u r n e d to its n o r m a l value w i t h i n 5 m i n . T h e i n c r e a s e d pressure
gradient is d u e to c r e a m i n g o r stratification o f the e m u l s i o n . A d d i t i o n a l
energy is r e q u i r e d o n restart to redisperse the m a t e r i a l u n i f o r m l y .
R e s t a r t i n g o f a phase-separated m i x t u r e (failed e m u l s i o n ) is s i m i l a r to
restarting an e m u l s i o n , b u t the starting pressure surge is substantially
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greater as a result o f total separation o f phases.

Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

Pressure Surge Range,

Fluid Reing Restarted Percent of Steady-State Pressure
Emulsion (30% water) 100-250, 200 typical
Emulsion (38% water) 100-150, 130 typical
Phase-separated mixture (30%) 400-800, 700 typical

Corrosion Considerations. C o r r o s i o n rates are d i c t a t e d b y the

p r o p e r t i e s o f the b r i n e b e i n g u s e d . P i l o t - p l a n t testing w i t h an e l e c t r o c h e m i ­
cal c o r r o s i o n rate p r o b e i n d i c a t e d c o r r o s i o n rates o f less t h a n 5 mils/year f o r
e m u l s i o n s flowing i n p i p e s . T h e c o r r o s i o n rate d e c l i n e d over t i m e , p r e s u m ­
ably because o f f o r m a t i o n o f an o i l layer o n the m e t a l . I n a l l p i l o t a n d field
tests that w e c o n d u c t e d , p i p e walls have always s h o w n a t h i n (approximately
0.001-in.) layer o f c r u d e o i l o n the w a l l after e m u l s i o n r u n s .
C o r r o s i o n rates for live b r i n e s c o n t a i n i n g C 0 o r H S are expected to b e
2 2

h i g h e r t h a n those m e a s u r e d o n d e a d brines i n p i l o t - p l a n t testing. O n - l i n e

c o r r o s i o n m o n i t o r i n g i n the field is i n d i c a t e d o n a case-by-case basis. C o r r o ­
s i o n rates for e m u l s i o n s are not expected to b e any w o r s e t h a n those f o r
c r u d e oils c o n t a i n i n g b r i n e .

Demulsification. T h e final part o f the e m u l s i o n transportation sys­

t e m is d e m u l s i f i c a t i o n o r b r e a k i n g o f the o i l - i n - w a t e r e m u l s i o n to r e c o v e r
dry c r u d e o i l . T h e e q u i p m e n t a n d process c o n d i t i o n s r e q u i r e d f o r this o p e r a ­
t i o n are the same or s i m i l a r to those u s e d for a c o n v e n t i o n a l c r u d e - o i l
d e w a t e r i n g process.
T h e t e c h n i q u e s u s e d f o r d e m u l s i f i c a t i o n o f a transport e m u l s i o n may
i n c l u d e r a i s i n g the t e m p e r a t u r e o f the e m u l s i o n , a d d i t i o n o f e m u l s i o n -
b r e a k i n g additives, a d d i t i o n o f diluents to r e d u c e the viscosity o f the heavy
c r u d e o i l , a n d the use o f e q u i p m e n t d e s i g n e d to p r o m o t e coalescence o f the
c r u d e - o i l d r o p l e t s . R a i s i n g the t e m p e r a t u r e o f the e m u l s i o n increases the

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 306 EMULSIONS IN THE PETROLEUM INDUSTRY

d i f f e r e n c e i n d e n s i t y b e t w e e n the h y d r o c a r b o n a n d aqueous phases a n d

encourages c r e a m i n g o f the e m u l s i o n . T h e r e d u c e d viscosity o f the h y d r o ­
c a r b o n phase at h i g h t e m p e r a t u r e s also i m p r o v e s the o p e r a b i l i t y o f the
d e m u l s i f i c a t i o n process. T h e viscosity o f the c r u d e o i l m a y also b e r e d u c e d
b y a d d i t i o n o f d i l u e n t s i f this o p e r a t i o n is a p p r o p r i a t e f o r d o w n s t r e a m p r o ­
cessing. T h e use o f d e m u l s i f y i n g additives is d e s i g n e d to counteract the
effects o f the e m u l s i f y i n g surfactants. T h e surfactants u s e d i n the s t a b i l i z a ­
t i o n o f e m u l s i o n s o f heavy c r u d e oils generally have a h i g h H L B ( h y d r o -
p h i l i c - l i p o p h i l i c balance). F o r d e m u l s i f i c a t i o n operations, the effectiveness
o f these surfactants m a y be c o u n t e r a c t e d b y a d d i t i o n o f surfactants w i t h a
l o w H L B . M a n y c o m m e r c i a l l y available p r o d u c t s w i t h p r o p r i e t a r y c o m p o ­
sitions are available f o r this p u r p o s e . E t h o x y l a t e d a l k y l p h e n o l s , w h i c h are
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u s e d i n the e m u l s i f i c a t i o n process, m a y also be u s e d f o r d e m u l s i f i c a t i o n i f

Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

c o m p o n e n t s are selected w i t h a l o w n u m b e r o f ethylene oxide groups.

T h e basic p r o c e d u r e f o r d e m u l s i f i c a t i o n o f a h e a v y - c r u d e - o i l transport
e m u l s i o n t h e n consists o f the f o l l o w i n g steps:

1. Raise the e m u l s i o n t e m p e r a t u r e to 190 to 250 °F.

2. A d d d e m u l s i f i c a t i o n surfactants.
3. P o s s i b l y a d d d i l u e n t s f o r viscosity r e d u c t i o n .
4. P r o v i d e residence t i m e sufficient f o r separation o f the o i l a n d
w a t e r phases.

T h e t i m e r e q u i r e d f o r separation i n step 4 d e p e n d s o n the density d i f f e r e n c e

b e t w e e n the o i l a n d w a t e r phases, the t r e a t i n g e q u i p m e n t , a n d the t r e a t i n g
temperature.
I n some cases it may b e desirable to p e r f o r m the d e m u l s i f i c a t i o n process
i n t w o stages. I n the first stage the b u l k o f the water m a y be r e m o v e d at a
m i n i m u m process severity, as already d e s c r i b e d . A s e c o n d process stage at a
h i g h e r t e m p e r a t u r e a n d p o s s i b l y at elevated pressure may t h e n be u s e d for
final d r y c r u d e - o i l recovery.
C h a n g e s i n process c o n t r o l p r o c e d u r e s f o r the d e m u l s i f i c a t i o n o p e r a ­
t i o n m a y be r e q u i r e d for o i l - i n - w a t e r e m u l s i o n s . Interface d e t e c t i o n i n s t r u ­
ments must b e able to detect the d i f f e r e n c e i n w a t e r a n d an o i l - i n - w a t e r
e m u l s i o n . A d j u s t m e n t o f c o n t r o l levels i n separation vessels may b e r e q u i r e d
for proper operation.
I n some cases, m i n i m a l effort is r e q u i r e d for the d e m u l s i f i c a t i o n p r o ­
cess. F o r example, i n field tests, adequate separation o f a b i t u m e n e m u l s i o n
c o u l d b e a c h i e v e d w i t h o u t the use o f d e m u l s i f i e r s b y r a i s i n g the t e m p e r a t u r e
o f the e m u l s i o n to 190 °F a n d p r o v i d i n g 24 to 48 h o f r e s i d e n c e t i m e i n
q u i e s c e n t storage tanks. H o w e v e r , p r o p e r s e l e c t i o n o f d e m u l s i f i c a t i o n
c h e m i c a l s is essential w h e n t r e a t i n g the e m u l s i o n s i n c o n v e n t i o n a l e q u i p ­
m e n t o n a c o n t i n u o u s - f l o w basis.

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 8. RIMMERETAL. Pipeline Emulsion Transportation for Heavy Oils 307

T h e w a t e r separated i n the d e m u l s i f i c a t i o n step is s i m i l a r i n character to

w a t e r p r o d u c e d i n a c o n v e n t i o n a l refinery d e s a l t i n g process. A l t h o u g h n o
d e t r i m e n t a l effects are a n t i c i p a t e d , the impacts o f surfactants i n the w a t e r o r
d o w n s t r e a m p r o c e s s i n g units m u s t b e evaluated f o r each specific case. T h e
w a t e r phase may c o n t a i n surfactant fragments that c o u l d r e q u i r e t r e a t m e n t
o r r e m o v a l p r i o r to d i s p o s a l . R e f i n e r i e s , h o w e v e r , use a variety o f c h e m i c a l s ,
catalysts, additives, etc., m a n y o f w h i c h e n d u p i n waste streams a n d r e q u i r e
treatment.

Storage, Maintenance, and Special Requirements. I f o i l - i n -

w a t e r e m u l s i o n s m u s t b e s t o r e d i n tanks e i t h e r b e f o r e o r after p i p e l i n i n g ,
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agitation is r e q u i r e d to p r e v e n t c r e a m i n g i n the tank. C r e a m i n g refers to the

c o n c e n t r a t i o n o f o i l droplets o n the surface o f the fluid that c a n result i n a
Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

t h i c k s k i n o r crust that may not r e a d i l y b e d i s p e r s e d i n t o the b u l k o f the

e m u l s i o n . S l o w agitation just sufficient to c o n t i n u a l l y r o l l the tank contents
w i l l p r e v e n t c r e a m i n g . Excessive agitation s h o u l d be a v o i d e d to p r e v e n t
shear d e g r a d a t i o n o f the e m u l s i o n .
M a i n t e n a n c e r e q u i r e m e n t s s h o u l d be the same f o r an e m u l s i o n p i p e l i n e
as f o r a c o n v e n t i o n a l p e t r o l e u m p i p e l i n e . S i m i l a r l y , n o u n u s u a l m a i n t e n a n c e
is e x p e c t e d for the e m u l s i o n p r e p a r a t i o n o r d e m u l s i f i c a t i o n parts o f the
system.
I f the p i p e l i n e u s e d f o r e m u l s i o n t r a n s p o r t a t i o n is a c o m m o n c a r r i e r ,
special p r o c e d u r e s may be necessary for m e t e r i n g a n d custody transfer. O n ­
l i n e i n s t r u m e n t s f o r m e a s u r e m e n t o f e m u l s i o n w a t e r content m a y b e re­
q u i r e d i n s u c h an a p p l i c a t i o n .

Economics
T h e e c o n o m i c analysis o f an e m u l s i o n p i p e l i n e transportation system is
h i g h l y site specific a n d d e p e n d s o n several factors that cannot be s p e c i f i e d
f o r a g e n e r a l case. H o w e v e r , e x a m p l e cases are p r e s e n t e d to illustrate t y p i c a l
costs associated w i t h use o f the technology.

Surfactant Cost. A m a j o r cost associated w i t h u s i n g o i l - i n - w a t e r

e m u l s i o n s is the cost o f the surfactants u s e d to stabilize the o i l d r o p l e t s
w i t h i n the e m u l s i o n . T h i s cost w i l l d e p e n d u p o n the surfactant f o r m u l a t i o n
c h o s e n f o r the specific a p p l i c a t i o n , the transportation distance i n v o l v e d , a n d
i n s o m e cases the type o f c r u d e o i l b e i n g e m u l s i f i e d . O n the basis o f the
f o r m u l a t i o n that w e t y p i c a l l y use a n d c u r r e n t m a r k e t p r i c e s , the e s t i m a t e d
surfactant cost to transport heavy c r u d e o i l as an e m u l s i o n f o r a distance o f
200 to 400 miles (322 to 644 k m ) is a p p r o x i m a t e l y $0.50 to $1.00 p e r b a r r e l
o f c r u d e o i l s h i p p e d . F o r greater p i p e l i n e lengths, u p to 1500 to 2000 m i l e s ,
the surfactant cost m a y increase b y 5 0 - 1 0 0 % relative to the shorter d i s -

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 308 EMULSIONS IN THE PETROLEUM INDUSTRY

tances. T h e s e costs are b a s e d o n conservative estimates o f the quantities o f

surfactants r e q u i r e d a n d m a y l i k e l y be r e d u c e d after o p t i m i z a t i o n f o r a
particular application.

Emulsion Transportation versus Diluent Recycle. T h e p r e ­

v a i l i n g m e t h o d i n use f o r t r a n s p o r t a t i o n o f heavy c r u d e o i l a n d b i t u m e n i n
A l b e r t a is to d i l u t e the c r u d e o i l w i t h a p p r o x i m a t e l y one part o f a l i g h t
h y d r o c a r b o n d i l u e n t , t y p i c a l l y n a t u r a l gas condensate, to t w o parts o f c r u d e
o i l . T h i s q u a n t i t y o f d i l u e n t is generally sufficient to r e d u c e the c r u d e - o i l
viscosity e n o u g h so that m i n i m u m p i p e l i n e specifications m a y be met. H o w ­
ever, a p o t e n t i a l shortage o f condensate d i l u e n t m a y l i m i t the use o f this
m e t h o d for h e a v y - c r u d e - o i l transportation. A n alternative to the o n c e -
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t h r o u g h use o f d i l u e n t is to r e c o v e r the d i l u e n t at the p i p e l i n e e n d b y

Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

f r a c t i o n a t i o n a n d recycle it to the start o f the p i p e l i n e . T h i s m e t h o d is

c o m p a r e d i n the f o l l o w i n g section w i t h the use o f o i l - i n - w a t e r e m u l s i o n s for
the same h y p o t h e t i c a l a p p l i c a t i o n . T h e basis f o r this example is a 2 4 - i n . , 200-
m i l e p i p e l i n e d e s i g n e d to transport 300,000 barrels p e r day o f b l e n d o r
200,000 barrels p e r day o f u n d i l u t e d heavy c r u d e o i l . A p a r a l l e l l i n e is
assumed f o r r e t u r n o f separated d i l u e n t . O t h e r bases a n d assumptions u s e d
i n the evaluation are as f o l l o w s :

Emulsion properties
Gravity 10° A P I (sp. gr. = 1)
Viscosity 100 cP
Crude-oil concentration 70%
Flow rate 286,000 barrels per day (45,474 m /day) 3

Surfactant cost $0.75 per barrel of crude oil

Water-disposal cost $0.20 per barrel of water
Tariffs
F o r blend $1.00 per barrel
F o r diluent $0.50 per barrel
F o r emulsion $0.50 per barrel
Fuel $5.00 per million Btu
Electricity $0.06 per kilowatt hour
Capital related costs 25% of total installed cost

T h e r e d u c e d tariffs for e m u l s i o n s c o m p a r e d to b l e n d are a s s u m e d b e ­

cause o f the 7 5 % r e d u c t i o n i n viscosity f o r emulsions versus b l e n d a n d the
resultant decrease i n p u m p i n g costs.
T h e c a l c u l a t e d c r u d e - o i l transportation cost f o r the e m u l s i o n case was
b a s e d o n estimates o f the r e q u i r e d c a p i t a l investments f o r e m u l s i f i c a t i o n
a n d o i l r e c o v e r y facilities, o p e r a t i n g costs i n c l u d i n g p i p e l i n e tariffs, surfac­
tant costs, a n d w a t e r disposal. T h e costs f o r the recycle b l e n d case i n c l u d e d
the n o r m a l p i p e l i n e o p e r a t i n g costs p l u s the costs o f separating a n d p u m p i n g
the d i l u e n t back to the start o f the p i p e l i n e . T h e costs assumed for the

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 8. RIMMERETAL. Pipeline Emulsion Transportation for Heavy Oils 309

e m u l s i o n ease w e r e based o n the a s s u m p t i o n that the costs o f c r u d e - o i l

p r o d u c t i o n facilities w i l l not be i n f l u e n c e d b y the subsequent c o n v e r s i o n o f
the p r o d u c e d c r u d e o i l to an o i l - i n - w a t e r e m u l s i o n . I n some cases, these
costs m a y be r e d u c e d b y r e d u c i n g the n o r m a l c r u d e - o i l d e w a t e r i n g r e q u i r e ­
ments necessary to m e e t u s u a l p i p e l i n e specifications (<0.5% H 0 ) . I n any 2

case h o w e v e r , c r u d e - o i l d r y i n g operations w i l l still be r e q u i r e d to a v o i d

p u m p i n g excess w a t e r i n the p i p e l i n e system.
A n alternative to the case d e s c r i b e d is one i n w h i c h the w a t e r separated
f r o m the e m u l s i o n is r e c y c l e d to the start o f the p i p e l i n e f o r reuse. W a t e r
recycle w o u l d e l i m i n a t e the p r o b l e m s a n d expense o f w a t e r d i s p o s a l a n d
w o u l d r e d u c e the r e q u i r e d q u a n t i t y o f surfactant, because a p o r t i o n o f the
surfactant w o u l d r e m a i n i n the separated water. F o r this case it is a s s u m e d
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that a 5 0 % r e c o v e r y o f surfactant c o u l d be a c h i e v e d after d e m u l s i f i c a t i o n .

Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

T h e disposal a n d recycle cases w e r e c o m p a r e d to an alternative trans­

p o r t a t i o n m e t h o d that i n c l u d e s f r a c t i o n a t i o n o f a light d i l u e n t f r a c t i o n f r o m
a h e a v y - c r u d e - o i l - d i l u e n t b l e n d a n d r e c y c l i n g o f the d i l u e n t to the start o f
the p i p e l i n e . F o r this case, an 8 5 % r e c o v e r y o f d i l u e n t f r o m the b l e n d was
a s s u m e d t o g e t h e r w i t h a loss i n value o f $5 p e r b a r r e l o f u n r e c o v e r e d
d i l u e n t . T h e e s t i m a t e d t r a n s p o r t a t i o n costs (dollars p e r b a r r e l o f c r u d e oil)
f o r the t h r e e cases are s u m m a r i z e d as f o l l o w s :

• e m u l s i o n w i t h w a t e r d i s p o s a l , $2.04

• e m u l s i o n w i t h w a t e r r e c y c l i n g , $1.97

• h e a v y - c r u d e - o i l - d i l u e n t b l e n d , $2.74

A d e t a i l e d b r e a k d o w n o f the c a p i t a l a n d o p e r a t i n g costs e s t i m a t e d f o r
the t h r e e cases is s h o w n i n T a b l e I. T h e analysis just p r e s e n t e d is f o r
i l l u s t r a t i o n o n l y , a n d the relative costs f o r any specific a p p l i c a t i o n r e q u i r e
f u r t h e r evaluation.

Economic Effects of Emulsion Water Concentration. A n

i m p o r t a n t p a r a m e t e r i n p r e p a r a t i o n o f an o i l - i n - w a t e r e m u l s i o n u s e d f o r
h e a v y - c r u d e - o i l t r a n s p o r t a t i o n is the c o n c e n t r a t i o n o f w a t e r o r b r i n e u s e d .
T h e e c o n o m i c effects o f this v a r i a b l e m a y be evaluated to d e t e r m i n e the
o p t i m a l value for m i n i m i z a t i o n o f the c r u d e - o i l t r a n s p o r t a t i o n cost. C h a n g e s
i n the w a t e r content o f a t r a n s p o r t e d e m u l s i o n m a i n l y affect the fluid viscos­
ity, the total fluid flow rate, a n d the v o l u m e o f w a t e r r e q u i r i n g d i s p o s a l o r
r e c y c l i n g . O t h e r system c o m p o n e n t s are also affected, i n c l u d i n g r a w w a t e r
h a n d l i n g , e m u l s i o n f o r m a t i o n , a n d d e m u l s i f i c a t i o n . F o r this i l l u s t r a t i o n , o n l y
the p i p e l i n e p u m p i n g costs a n d w a t e r - d i s p o s a l costs are c o n s i d e r e d . I n a
c o m m e r c i a l p i p e l i n e system, the selection o f the e m u l s i o n w a t e r content
m a y b e b a s e d o n tariffs rather t h a n o n p u m p i n g costs. T h i s analysis is b a s e d
o n l y o n the actual p u m p i n g costs i n c u r r e d .

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 310 EMULSIONS IN THE PETROLEUM INDUSTRY

Table I. Transportation Costs for an Emulsion-

Transport System Compared to Diluent Recycling
Emulsion System
Water Water Diluent
Item Disposal Recycle Recycle
Capital Costs, million dollars
Emulsification system 3.5 3.5
Emulsion separation 33.6 33.6
Diluent recovery 72.0
Total 37.1 37.1 72.0
Operating Costs, dollars per barrel
Surfactants 0.75 0.56
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Fuel 0.20 0.20 0.52

Tariffs 0.71 0.92 1.50
Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

Water disposal 0.09

Maintenance and labor 0.07 0.07 0.10
Diluent makeup 0.37
Miscellaneous 0.10 0.10
Subtotal 1.92 1.85 2.49
Capital-related costs 0.12 0.12 0.25
Total 2.04 1.97 2.74

T h e e m u l s i o n w a t e r c o n c e n t r a t i o n has a d o u b l e effect o n p u m p i n g costs.

F o r a fixed flow rate o f c r u d e o i l , as the w a t e r content increases, the total
v o l u m e flowing increases, w h i c h increases the cost o f p u m p i n g . H o w e v e r ,
a d d i t i o n a l w a t e r i n the e m u l s i o n also reduces its viscosity a n d t h e r e b y lowers
p u m p i n g costs. T h e s e t w o factors t e n d to offset each o t h e r f o r e m u l s i o n
c r u d e - o i l concentrations i n the 5 0 - 7 0 % range. A t h i g h e r o i l concentrations,
the viscosity increases m o r e r a p i d l y , a n d this situation reduces the i n c e n t i v e
f o r f u r t h e r w a t e r r e d u c t i o n s . C o r r e l a t i o n s o f e m u l s i o n viscosity as a f u n c t i o n
o f w a t e r c o n c e n t r a t i o n , s u c h as w e r e d e s c r i b e d earlier, are r e q u i r e d to
p e r f o r m this analysis. C a l c u l a t i o n s w e r e p e r f o r m e d f o r a h y p o t h e t i c a l p i p e ­
l i n e system w i t h the f o l l o w i n g characteristics:

• l e n g t h , 200 miles
• d i a m e t e r , 12 i n .

• c r u d e - o i l gravity, 10° A P I
• c r u d e - o i l flow rate, 50,000 barrels p e r day
• p u m p efficiency, 6 7 %
• e l e c t r i c i t y cost, $0.05 p e r k i l o w a t t h o u r
• w a t e r d i s p o s a l , $0.20 p e r b a r r e l

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 8. RIMMER ET AL. Pipeline Emulsion Transportation for Heavy Oils 311

T h e results o f this analysis are s h o w n i n F i g u r e 5. T h e e m u l s i o n p u m p ­

i n g cost is m i n i m i z e d f o r the h y p o t h e t i c a l p i p e l i n e system at an e m u l s i o n
c r u d e - o i l c o n c e n t r a t i o n i n the 6 0 - 6 2 % range, a n d the w a t e r - d i s p o s a l costs
naturally decrease c o n t i n u o u s l y as e m u l s i o n w a t e r content is decreased. T h e
total cost f o r this case reaches a m i n i m u m at about 7 6 % c r u d e o i l i n the
emulsion.
T h i s evaluation illustrates that e m u l s i o n water c o n c e n t r a t i o n s h o u l d
generally be r e d u c e d u n t i l the viscosity begins to be significantly i n c r e a s e d .
I n s e l e c t i n g the actual o p t i m u m c o n c e n t r a t i o n f o r a specific case, o t h e r
factors s u c h as the effect o f w a t e r c o n c e n t r a t i o n o n e m u l s i o n stability, the
effect o f total flow rate o n p u m p efficiency, a n d the cost a n d availability o f
w a t e r s h o u l d also be c o n s i d e r e d .
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Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

Conclusions
O i l - i n - w a t e r e m u l s i o n t e c h n o l o g y for t r a n s p o r t a t i o n o f heavy c r u d e oils a n d
b i t u m e n s p r o v i d e s a viable alternative f o r the use o f d i l u e n t s o r h e a t e d
p i p e l i n e s . Surfactant f o r m u l a t i o n s that have b e e n d e v e l o p e d p r o v i d e stable

Figure 5. Total operating costs, minimized in emulsions containing high con-

centrations of crude oil.

In Emulsions; Schramm, L.;

Advances in Chemistry; American Chemical Society: Washington, DC, 1992.
 312 EMULSIONS IN THE PETROLEUM INDUSTRY

o p e r a t i o n a n d adequate e m u l s i o n l i f e . M e t h o d s are available f o r t h e f o r m a ­

t i o n o f e m u l s i o n s w i t h d e s i r e d p r o p e r t i e s f o r efficient p i p e l i n e o p e r a t i o n .
F u r t h e r d e v e l o p m e n t o f e m u l s i o n transport t e c h n o l o g y is d e p e n d e n t
u p o n f u t u r e e c o n o m i c factors s u c h as increases i n t h e p r i c e o f heavy c r u d e
o i l a n d p o t e n t i a l shortages o f d i l u e n t . C o m m e r c i a l o p e r a t i o n o f an e m u l s i o n
transport system is r e q u i r e d to d e t e r m i n e t h e l o n g - t e r m t e c h n i c a l a n d eco­
n o m i c v i a b i l i t y o f this t e c h n o l o g y .

References
1. Oil Gas J. 1972, 2(17), 37.
Downloaded by UNIV OF ARIZONA on December 7, 2012 | http://pubs.acs.org

2. Marsden, S. S.; Rose, S. C . Oil Gas J. 1971, 10(11), 24.

3. Simon, R.; Poynter, W . G . Presented at the 43rd Annual Meeting of the Society of
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