Glossary of Petroleum Emulsion Terms - American Chemical Society

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Glossary of Petroleum Emulsion Terms Laurier L . Schramm Petroleum Recovery Institute, 3512 33rd Street N.W., Calgary, Alberta, Canada T 2 L 2A6

This glossary provides brief explanations for nearly 200 important terms in the science and engineering of petroleum emulsions. The field of petroleum emulsions encompasses aspects of so many different disciplines that there exists a voluminous body of terminology. A selection of frequently encountered terms has been made including scientific terms related to the basic principles and properties of emulsions, and petroleum production and processing terms used to describe practical emulsions and their treatment. In addition, crossreferences for the more important synonyms and abbreviations are included.

X J L VAST POTENTIAL L E X I C O N is associated w i t h t h e field o f p e t r o l e u m e m u l s i o n s , p a r t l y because o f the d i v e r s i t y o f o c c u r r e n c e s a n d p r o p e r t i e s o f p e t r o l e u m e m u l s i o n s , a n d p a r t l y because o f t h e m a n y scientific d i s c i p l i n e s i n v o l v e d i n t h e i r study a n d treatment, e a c h d i s c i p l i n e b r i n g i n g elements o f its o w n special language. T h i s glossary presents some o f the m o r e c o m m o n t e r m s u s e d i n t h e science a n d t e c h n o l o g y o f e m u l s i o n s . T h e selections have b e e n c h o s e n to encompass the m o r e i m p o r t a n t e m u l s i o n terms u s e d i n the chapters o f this b o o k , a n d t h e explanations p r e s e n t e d are consistent w i t h t h e usage i n those chapters. N o attempt has b e e n m a d e to i n c l u d e every t e r m that m a y b e e n c o u n t e r e d i n d e a l i n g w i t h p e t r o l e u m e m u l s i o n s . S o m e basic k n o w l e d g e o f u n d e r l y i n g fields s u c h as p h y s i c a l c h e m i s t r y a n d c h e m i c a l e n g i n e e r i n g is a s s u m e d . M a n y n a m e d e m u l s i o n s a n d p h e n o m e n a (such as P i c k e r i n g e m u l s i o n s ) have b e e n i n c l u d e d , b u t n a m e d equations a n d constants have g e n e r a l l y n o t b e e n included. 0065-2393/92/0231-0385 $06.25/0 © 1992 American Chemical Society

In Emulsions; Schramm, L.; Advances in Chemistry; American Chemical Society: Washington, DC, 1992.

386

E M U L S I O N S I N T H E P E T R O L E U M INDUSTRY

S o m e terms are u s e d i n o t h e r ways b y o t h e r researchers, o r i n o t h e r c o u n t r i e s , a n d m a y have l e g a l d e f i n i t i o n s d i f f e r e n t f r o m those g i v e n h e r e . T h e d i s t i n c t i o n s d r a w n a m o n g l i g h t , heavy, extra-heavy, a n d b i t u m i n o u s c r u d e oils w e r e m a d e o n t h e basis o f U n i t e d N a t i o n s Institute f o r T r a i n i n g a n d R e s e a r c h ( U N I T A R ) - s p o n s o r e d discussions a i m e d at e s t a b l i s h i n g s u c h d e f i n i t i o n s (1-3).

F o r terms d r a w n f r o m t h e area o f c o l l o i d a n d i n t e r f a c e

science, m u c h r e l i a n c e was p l a c e d o n t h e r e c o m m e n d a t i o n s o f t h e I U P A C C o m m i s s i o n o n C o l l o i d a n d Surface C h e m i s t r y (4). F o r i m p o r t a n t e m u l s i o n


terms that are f r e q u e n t l y u s e d i n i n d u s t r i a l p r a c t i c e , t h e a i m was to b e consistent w i t h t h e standard p e t r o l e u m d i c t i o n a r i e s s u c h as references 5 - 7 .

Absolute

Viscosity

A t e r m u s e d to i n d i c a t e viscosity m e a s u r e d b y a stand

a r d m e t h o d , w i t h t h e results traceable to f u n d a m e n t a l u n i t s . A b s o l u t e viscos ities are d i s t i n g u i s h e d f r o m relative measurements

made with instruments

that measure viscous d r a g i n a fluid, w i t h o u t k n o w n and/or u n i f o r m a p p l i e d shear rates. See also V i s c o s i t y . Acid Number

See T o t a l A c i d N u m b e r .

A l k a n e C a r b o n N u m b e r , see E q u i v a l e n t A l k a n e C a r b o n N u m b e r .

ACN

Adsorption

T h e increase i n q u a n t i t y o f a c o m p o n e n t at a n i n t e r f a c e . I n

most usage i t is p o s i t i v e , b u t i t c a n b e negative. A d s o r p t i o n m a y also denote the process o f c o m p o n e n t s a c c u m u l a t i n g at a n interface. Aggregation

T h e process o f f o r m i n g a g r o u p o f d r o p l e t s that are h e l d

t o g e t h e r i n s o m e way. F o r e m u l s i o n s , this process is sometimes r e f e r r e d to as c o a g u l a t i o n o r Aging

flocculation.

T h e p r o p e r t i e s o f e m u l s i o n s , a n d o f c r u d e oils, m a y change w i t h

t i m e i n storage. A g i n g i n c r u d e oils m a y r e f e r to changes i n c o m p o s i t i o n d u e to o x i d a t i o n , p r e c i p i t a t i o n o f c o m p o n e n t s , b a c t e r i a l a c t i o n , o r e v a p o r a t i o n o f c o m p o n e n t s that have l o w b o i l i n g p o i n t s . A g i n g i n e m u l s i o n s m a y r e f e r to any o f aggregation, c o a l e s c e n c e , c r e a m i n g , o r c h e m i c a l changes. A g e d e m u l sions f r e q u e n t l y have l a r g e r d r o p l e t sizes. Alkane Carbon Number (ACN) Amphoteric ter

of

the

Surfactant polar

A surfactant m o l e c u l e f o r w h i c h t h e i o n i c charac

group

lauramidopropylbetaine, C

See E q u i v a l e n t A l k a n e C a r b o n N u m b e r .

depends 1 1

H

2 3

on

solution

p H . For

example,

C O N H ( C H ) 3 N ( C H ) C H C O O - , is p o s i 2

+

3

2

2

t i v e l y c h a r g e d at l o w p H b u t is e l e c t r i c a l l y n e u t r a l , h a v i n g b o t h positive a n d negative charges at i n t e r m e d i a t e p H . O t h e r c o m b i n a t i o n s are possible, a n d


387

GLOSSARY

some a m p h o t e r i c surfactants are negatively c h a r g e d at h i g h p H . See also Z w i t t e r i o n i c Surfactant. Anionic

A surfactant m o l e c u l e w h o s e p o l a r g r o u p is nega

Surfactant

tively c h a r g e d . E x a m p l e : s o d i u m d o d e c y l sulfate, C H 3 ( C H 2 ) S 0 ~ N a . n


Anisokinetic

Sampling

4

+

See I s o k i n e t i c S a m p l i n g .

A m e a s u r e o f t h e relative d e n s i t y (specific gravity) o f p e t r o

API Gravity

l e u m l i q u i d s . T h e A P I gravity, i n degrees, is g i v e n b y A P I = (141.5/relative density) - 131.5 w h e r e t h e relative d e n s i t y at t e m p e r a t u r e Τ (°C) equals t h e d e n s i t y at Τ d i v i d e d b y the d e n s i t y o f w a t e r at 15.6 °C. Apparent

Viscosity

Viscosity determined for a non-Newtonian

fluid

w i t h o u t r e f e r e n c e to a p a r t i c u l a r shear rate f o r w h i c h it a p p l i e s . S u c h v i s c o s i ties are u s u a l l y d e t e r m i n e d b y a m e t h o d s t r i c t l y a p p l i c a b l e to N e w t o n i a n fluids o n l y . A n a t u r a l l y o c c u r r i n g h y d r o c a r b o n that is a s o l i d at r e s e r v o i r

Asphalt

t e m p e r a t u r e s . A n asphalt r e s i d u e m a y also b e p r e p a r e d f r o m heavy (asphaltic) c r u d e oils o r b i t u m e n , f r o m w h i c h l o w e r b o i l i n g fractions have b e e n removed. Asphaltene

A p o l y a r o m a t i c c o m p o n e n t o f some c r u d e oils that has a h i g h

m o l e c u l a r mass a n d also h i g h s u l f u r , n i t r o g e n , oxygen, a n d m e t a l contents. I n p r a c t i c a l w o r k asphaltenes are u s u a l l y d e f i n e d o p e r a t i o n a l l y b y u s i n g a s t a n d a r d i z e d separation s c h e m e . O n e s u c h s c h e m e defines asphaltenes as those c o m p o n e n t s o f a c r u d e o i l o r b i t u m e n that are s o l u b l e i n t o l u e n e b u t insoluble i n n-pentane. Basic Sediment and Water

T h a t p o r t i o n o f solids a n d aqueous s o l u t i o n i n

an e m u l s i o n that separates o n s t a n d i n g , o r is separated b y c e n t r i f u g i n g , i n a s t a n d a r d i z e d test m e t h o d . B a s i c s e d i m e n t m a y c o n t a i n e m u l s i f i e d o i l as w e l l . A l s o r e f e r r e d to as B S & W , B S W , b o t t o m settlings a n d w a t e r , o r b o t t o m solids a n d water. Batch

Treating

I n o i l p r o d u c t i o n o r p r o c e s s i n g , the process i n w h i c h

e m u l s i o n is c o l l e c t e d i n a tank a n d t h e n b r o k e n i n a b a t c h . T h i s m e t h o d is as o p p o s e d to c o n t i n u o u s , o r flow-line, t r e a t i n g o f e m u l s i o n s . Bicontinuous

Microemulsion

A possible

structure

for middle-phase

m i c r o e m u l s i o n s is o n e i n w h i c h b o t h o i l a n d w a t e r phases are c o n t i n u o u s t h r o u g h o u t t h e m i c r o e m u l s i o n phase. A n analogy is t h e s t r u c t u r e o f p o r o u s


388


rock, i n w h i c h b o t h the m i n e r a l phase a n d t h e p o r e - t h r o a t channels c a n b e c o n t i n u o u s at t h e same t i m e . See also M i d d l e - P h a s e M i c r o e m u l s i o n . Bitumen A n a t u r a l l y o c c u r r i n g viscous h y d r o c a r b o n h a v i n g a viscosity greater t h a n 10,000 mPa-s at a m b i e n t deposit t e m p e r a t u r e , a n d a d e n s i t y greater than 1000 kg/m at 15.6 °C. I n a d d i t i o n to h y d r o c a r b o n s o f h i g h m o l e c u l a r mass, b i t u m e n contains a p p r e c i a b l e quantities o f s u l f u r , n i t r o g e n , oxygen, a n d heavy metals. Downloaded by NORTH CAROLINA STATE UNIV on December 7, 2012 | http://pubs.acs.org Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch011

3

Bottle Test A n e m p i r i c a l test i n w h i c h v a r y i n g amounts o f a p o t e n t i a l d e m u l s i f i e r are a d d e d i n t o a series o f tubes o r bottles c o n t a i n i n g subsamples o f an e m u l s i o n to b e b r o k e n . A f t e r some s p e c i f i e d t i m e , t h e extent o f phase separation a n d appearance o f the interface separating t h e phases are n o t e d . T h e r e are m a n y variations o f this test. I n a d d i t i o n to t h e d e m u l s i f i e r , a d i l u e n t may b e a d d e d to r e d u c e viscosity. I n t h e c e n t r i f u g e test, c e n t r i f u g a l f o r c e m a y b e a d d e d to s p e e d u p t h e phase separation. T h e r e are also m a n y variations o f the c e n t r i f u g e test. Bottom Settlings and Water Breaking

See B a s i c S e d i m e n t a n d W a t e r .

T h e process i n w h i c h a n e m u l s i o n separates, t h e f o r m e r l y d i s

p e r s e d phase b e c o m i n g a c o n t i n u o u s phase, separate f r o m t h e o r i g i n a l c o n t i n u o u s phase. See B a s i c S e d i m e n t a n d W a t e r .

BS&W

Bulk Phase U s u a l l y refers to a d i s p e r s i o n as a w h o l e . F o r e x a m p l e , i n a n e m u l s i o n the t e r m " b u l k phase v i s c o s i t y " refers to t h e e m u l s i o n viscosity, as o p p o s e d t o t h e c o n t i n u o u s - p h a s e viscosity. T h u s t h e b u l k phase is not a separate, single phase at a l l a n d m a y c o n t a i n d i s p e r s e d s o l i d a n d l i q u i d phases. Capillary Forces T h e i n t e r f a c i a l forces acting a m o n g o i l , water, a n d s o l i d i n a p o r o u s m e d i u m . T h e s e d e t e r m i n e t h e pressure d i f f e r e n c e (capillary pressure) across a n o i l - w a t e r interface i n a p o r e . C a p i l l a r y forces are largely r e s p o n s i b l e f o r o i l e n t r a p m e n t u n d e r t y p i c a l reservoir c o n d i t i o n s . Capillary Number (N ) A d i m e n s i o n l e s s ratio o f viscous to c a p i l l a r y forces. O n e f o r m gives N as v e l o c i t y times viscosity d i v i d e d b y i n t e r f a c i a l t e n s i o n . It is u s e d t o i n d i c a t e h o w strongly t r a p p e d r e s i d u a l o i l is i n a p o r o u s medium. c

c

Capillary

Pressure

T h e l o c a l pressure d i f f e r e n c e across t h e o i l - w a t e r

interface i n a p o r e c o n t a i n e d i n a p o r o u s m e d i u m . O n e o f the l i q u i d s u s u a l l y


389

GLOSSARY

p r e f e r e n t i a l l y wets t h e s o l i d ; thus t h e c a p i l l a r y pressure is n o r m a l l y taken as the pressure i n t h e n o n w e t t i n g fluid m i n u s that i n t h e w e t t i n g Cationic

Surfactant

fluid.

A surfactant m o l e c u l e w h o s e p o l a r g r o u p is p o s i

tively c h a r g e d . E x a m p l e : c e t y l t r i m e t h y l a m m o n i u m b r o m i d e , C H ( C H 2 ) i 5 3

N (CH ) Br-. +


CCC

3

3

See C r i t i c a l C o a g u l a t i o n C o n c e n t r a t i o n .

Centrifugal Centrifuge

Separator Test

See Separator.

See B o t t l e T e s t .

Chocolate Mousse Emulsion A n a m e f r e q u e n t l y u s e d to refer to t h e w a t e r - i n - o i l e m u l s i o n s h a v i n g a h i g h water c o n t e n t that are f o r m e d w h e n c r u d e oils are s p i l l e d o n t h e oceans. T h e n a m e reflects t h e c o l o r a n d v e r y viscous consistency o f these e m u l s i o n s . It has also b e e n a p p l i e d to o t h e r p e t r o l e u m e m u l s i o n s o f s i m i l a r appearance. CMC

See C r i t i c a l M i c e l l e C o n c e n t r a t i o n .

Coagulation

See A g g r e g a t i o n .

Coalescence

T h e m e r g i n g o f t w o o r m o r e droplets i n t o a single d r o p l e t . I n

an e m u l s i o n coalescence reduces t h e total n u m b e r o f d r o p l e t s a n d also t h e total i n t e r f a c i a l area. Coefficient

of Viscosity

See V i s c o s i t y

Colloidal A state o f s u b d i v i s i o n i n w h i c h t h e particles, d r o p l e t s , o r b u b bles d i s p e r s e d i n another phase have at least o n e d i m e n s i o n (e.g., diameter) b e t w e e n ~ 1 a n d 1000 n m . T h i s d e f i n i t i o n i n c l u d e s c o l l o i d s as a category o f dispersions. Condensate

A n y light-hydrocarbon liquid mixture obtained from the con

d e n s a t i o n o f h y d r o c a r b o n gases. C o n d e n s a t e t y p i c a l l y contains m o s t l y p r o p a n e , butane, a n d p e n t a n e . Contact Angle W h e n two i m m i s c i b l e fluids (e.g., l i q u i d - g a s o r o i l - w a t e r ) are b o t h i n contact w i t h a s o l i d , t h e angle f o r m e d b e t w e e n t h e s o l i d surface and t h e surface o f the m o r e dense fluid phase is t e r m e d t h e contact angle. B y c o n v e n t i o n , i f one o f t h e fluids is water, t h e n t h e contact angle is t h e angle m e a s u r e d t h r o u g h t h e w a t e r phase.


390

EMULSIONS IN T H E PETROLEUM

INDUSTRY

Continuous Phase I n a n e m u l s i o n , a l i q u i d phase i n w h i c h are d i s p e r s e d droplets o f an immiscible l i q u i d o f a different composition. Also called external phase. Continuous

Treating

See F l o w - L i n e T r e a t i n g .


Cosurfactant A n y c h e m i c a l , w h e t h e r surface active b y i t s e l f o r n o t , that m a y b e a d d e d to a system to e n h a n c e t h e effectiveness o f a surfactant. Creaming T h e process o f e m u l s i o n droplets floating u p w a r d s u n d e r grav ity o r a c e n t r i f u g a l field to f o r m a c o n c e n t r a t e d e m u l s i o n (cream) q u i t e d i s t i n c t f r o m t h e u n d e r l y i n g d i l u t e e m u l s i o n . C r e a m i n g is not t h e same as the b r e a k i n g o f an e m u l s i o n . See also S e d i m e n t a t i o n . Critical Coagulation Concentration (CCC) T h e electrolyte c o n c e n t r a t i o n that marks the onset o f c o a g u l a t i o n . T h e C C C is v e r y system-specific, a l t h o u g h t h e v a r i a t i o n i n C C C w i t h electrolyte c o m p o s i t i o n has b e e n e m p i r i cally g e n e r a l i z e d . See also S c h u l z e - H a r d y R u l e . Critical Micelle Concentration (CMC) T h e surfactant c o n c e n t r a t i o n above w h i c h m i c e l l e s b e g i n to b e f o r m e d . I n p r a c t i c e a n a r r o w range o f surfactant concentrations represents t h e t r a n s i t i o n f r o m a s o l u t i o n i n w h i c h o n l y single, unassociated surfactant m o l e c u l e s ( m o n o m e r s ) are p r e s e n t to a solution containing micelles. Crude Oil A n a t u r a l l y o c c u r r i n g h y d r o c a r b o n p r o d u c e d f r o m a n u n d e r g r o u n d reservoir. See also A s p h a l t , B i t u m e n , E x t r a - H e a v y C r u d e O i l , H e a v y Crude Oil, Light Crude Oil, O i l . Cuff Layer Emulsion Darcy's

Law

See Interface E m u l s i o n .

See P e r m e a b i l i t y .

Demulsifier 1. C h e m i c a l : A n y agent a d d e d to a n e m u l s i o n that causes o r enhances t h e rate o f b r e a k i n g o f the e m u l s i o n (separation i n t o its constituent l i q u i d phases). D e m u l s i f i e r s m a y act b y any o f a n u m b e r o f d i f f e r e n t m e c h a nisms. 2. D e v i c e : A n y d e v i c e that is u s e d to b r e a k e m u l s i o n s . S u c h devices m a y e m p l o y c h e m i c a l , e l e c t r i c a l , o r m e c h a n i c a l means, o r a c o m b i n a t i o n , to b r e a k a n e m u l s i o n a n d cause separation i n t o its constituent l i q u i d phases. Desalter

A n o i l - f i e l d o r refinery apparatus u s e d to separate water a n d

associated d i s s o l v e d salts f r o m c r u d e o i l .


391

GLOSSARY

Detergent

See Surfactant.

Differential

Viscosity

T h e rate o f c h a n g e o f shear stress w i t h respect to

shear rate, taken at a specific shear rate (r/ D

Diffuse Layer

dr/dy).

See E l e c t r i c D o u b l e L a y e r .


Dilatant A fluid f o r w h i c h viscosity increases as t h e shear rate increases. A l s o t e r m e d shear t h i c k e n i n g . Diluent

A l o w - b o i l i n g - p o i n t p e t r o l e u m f r a c t i o n , s u c h as n a p h t h a , that is

a d d e d t o a m o r e viscous h i g h - b o i l i n g - p o i n t p e t r o l e u m l i q u i d o r o i l - c o n t i n u ous e m u l s i o n . T h e d i l u e n t is usually a d d e d to r e d u c e viscosity. Dispersed Phase I n a n e m u l s i o n , t h e droplets that are d i s p e r s e d o r sus p e n d e d i n an immiscible l i q u i d o f a different composition. Also called inter n a l phase. Dispersion 1. I n c o l l o i d s , a system i n w h i c h finely d i v i d e d d r o p l e t s , p a r t i cles, o r b u b b l e s are d i s t r i b u t e d i n a n o t h e r phase. A s i t is u s u a l l y u s e d , d i s p e r s i o n i m p l i e s a d i s t r i b u t i o n w i t h o u t d i s s o l u t i o n . A n e m u l s i o n is a n example o f a c o l l o i d a l d i s p e r s i o n (see also C o l l o i d a l ) . 2. I n o i l r e c o v e r y f r o m a reservoir, t h e m i x i n g b y c o n v e c t i o n o f fluids flow ing i n a porous m e d i u m . DLVO Theory A n a c r o n y m for a theory o f the stability o f c o l l o i d a l d i s p e r sions d e v e l o p e d i n d e p e n d e n t l y b y B . D e r j a g u i n a n d L . D . L a n d a u i n o n e laboratory a n d b y E . J . W . V e r w e y a n d J . T h . G . O v e r b e e k i n another. T h e theory was d e v e l o p e d to a c c o u n t f o r t h e stability against aggregation o f electrostatically c h a r g e d particles i n a d i s p e r s i o n . Double

Layer

See E l e c t r i c D o u b l e L a y e r .

Drilling Fluid T h e c i r c u l a t i n g fluid u s e d w h e n d r i l l i n g a w e l l . T h e d r i l l i n g fluid lubricates t h e d r i l l b i t , forces cuttings o u t o f t h e w e l l b o r e u p t o t h e surface, a n d m a y also p r e v e n t b l o w o u t s . D r i l l i n g fluids are u s u a l l y suspen sions, b u t e m u l s i o n s a n d foams may also b e u s e d . T h e t e r m s " d r i l l i n g fluid" a n d " d r i l l i n g m u d " are u s e d interchangeably. EACN

See E q u i v a l e n t A l k a n e C a r b o n N u m b e r .

Electric Double Layer A n idealized description o f the distribution o f free charges i n t h e n e i g h b o r h o o d o f a n i n t e r f a c e . T y p i c a l l y a p a r t i c l e o r


392



d r o p l e t surface is v i e w e d as h a v i n g a fixed charge o f o n e sign (one layer), w h i l e o p p o s i t e l y c h a r g e d ions are d i s t r i b u t e d d i f f u s e l y i n t h e adjacent l i q u i d (the s e c o n d layer). T h e s e c o n d layer m a y b e c o n s i d e r e d to b e m a d e u p o f a relatively less m o b i l e S t e r n layer i n close p r o x i m i t y to t h e surface, a n d a relatively m o r e d i f f u s e layer at greater distance. Electrophoresis T h e m o t i o n o f c o l l o i d a l species c a u s e d b y a n i m p o s e d e l e c t r i c field. T h e species m o v e w i t h a n e l e c t r o p h o r e t i c v e l o c i t y that d e p e n d s o n t h e i r electric charge a n d t h e e l e c t r i c field gradient. T h e electro p h o r e t i c m o b i l i t y is t h e e l e c t r o p h o r e t i c v e l o c i t y p e r u n i t e l e c t r i c field g r a d i ent a n d is u s e d to characterize specific systems. Electrophoretic

Mobility

See E l e c t r o p h o r e s i s .

Electrostatic Treater A vessel u s e d to break e m u l s i o n s b y p r o m o t i n g coalescence t h r o u g h t h e a p p l i c a t i o n o f a n e l e c t r i c field. See also T r e a t e r . Emulsifier A n y agent that acts to stabilize a n e m u l s i o n . T h e e m u l s i f i e r m a y m a k e i t easier to f o r m a n e m u l s i o n , p r o v i d e stability against aggrega t i o n , o r p r o v i d e stability against coalescence. E m u l s i f i e r s are f r e q u e n t l y b u t not necessarily surfactants. Emulsion A d i s p e r s i o n o f droplets o f o n e l i q u i d i n another, i m m i s c i b l e l i q u i d , i n w h i c h the droplets are o f c o l l o i d a l o r n e a r - c o l l o i d a l sizes. Emulsion

Drilling

Fluid

See D r i l l i n g F l u i d .

Emulsion Test I n g e n e r a l , e m u l s i o n tests range f r o m s i m p l e i d e n t i f i c a tions o f e m u l s i o n presence a n d v o l u m e to d e t a i l e d c o m p o n e n t analyses. T h e t e r m " e m u l s i o n t e s t " f r e q u e n t l y refers s i m p l y to t h e d e t e r m i n a t i o n o f s e d i ments i n a n e m u l s i o n o r o i l s a m p l e . See also Basic S e d i m e n t a n d W a t e r . Emulsion

Treater

See T r e a t e r .

Enhanced Oil Recovery T h e t h i r d phase o f c r u d e - o i l p r o d u c t i o n , i n w h i c h c h e m i c a l , m i s c i b l e fluid, o r t h e r m a l m e t h o d s are a p p l i e d to restore p r o d u c t i o n f r o m a d e p l e t e d reservoir. A l s o k n o w n as tertiary o i l recovery. See also P r i m a r y O i l R e c o v e r y , S e c o n d a r y O i l R e c o v e r y . Equivalent Alkane Carbon Number (EACN) E a c h surfactant o r surfac tant m i x t u r e i n a reference series w i l l p r o d u c e a m i n i m u m i n t e r f a c i a l t e n s i o n ( I F T ) f o r a d i f f e r e n t n - a l k a n e . F o r any c r u d e o i l o r o i l c o m p o n e n t , a m i n i m u m I F T w i l l b e o b s e r v e d against o n e o f t h e r e f e r e n c e surfactants. T h e E A C N f o r t h e c r u d e o i l refers to the n - a l k a n e that w o u l d y i e l d m i n i m u m


393

GLOSSARY

I F T against that r e f e r e n c e surfactant. T h e E A C N thus allows p r e d i c t i o n s to be m a d e about the i n t e r f a c i a l t e n s i o n b e h a v i o r o f a c r u d e o i l i n the p r e s e n c e o f surfactant. See references 8 a n d 9. External

Phase

T h e c o n t i n u o u s phase o f an e m u l s i o n , i n w h i c h droplets


o f a s e c o n d phase are d i s p e r s e d . Extra-Heavy Crude Oil A n a t u r a l l y o c c u r r i n g h y d r o c a r b o n h a v i n g a vis cosity less than 10,000 mPa-s at a m b i e n t deposit t e m p e r a t u r e a n d a d e n s i t y greater t h a n 1000 k g / m at 15.6 °C. 3

See A g g r e g a t i o n .

Flocculation Flotation

See

Sedimentation.

Flow-Line Treating I n o i l p r o d u c t i o n o r p r o c e s s i n g , the process i n w h i c h e m u l s i o n is c o n t i n u o u s l y b r o k e n a n d separated i n t o o i l a n d w a t e r b u l k phases. A l s o c a l l e d c o n t i n u o u s t r e a t i n g . T h i s m e t h o d is as o p p o s e d to b a t c h t r e a t i n g o f e m u l s i o n s . See also B a t c h T r e a t i n g , T r e a t e r . Foam

A d i s p e r s i o n o f gas b u b b l e s , i n a l i q u i d or s o l i d , i n w h i c h at least one

d i m e n s i o n falls w i t h i n the c o l l o i d a l size range. T h u s a f o a m t y p i c a l l y contains either v e r y s m a l l b u b b l e sizes or, m o r e c o m m o n l y , quite large gas b u b b l e s separated b y t h i n l i q u i d films. Free Water

T h e r e a d i l y separated, n o n e m u l s i f i e d , w a t e r that is c o p r o -

duced with oil from a production well. Free-Water Knockout (FWKO) A vessel d e s i g n e d to separate the r e a d i l y separated ( n o n e m u l s i f i e d o r " f r e e " ) w a t e r f r o m o i l o r an o i l - c o n t a i n i n g e m u l s i o n . F u r t h e r w a t e r a n d solids r e m o v a l m a y be a c c o m p l i s h e d i n a treater. FWKO

See F r e e - W a t e r K n o c k o u t .

Gas Emulsion

A t e r m u s e d to d e s c r i b e c r u d e o i l that contains a s m a l l

v o l u m e f r a c t i o n o f d i s p e r s e d gas. Gravity

Separator

See

Separator.

Gun Barrel A type o f settling vessel u s e d to separate w a t e r a n d o i l f r o m an e m u l s i o n . T y p i c a l l y , h e a t e d e m u l s i o n is treated w i t h d e m u l s i f i e r a n d i n t r o d u c e d i n t o the g u n b a r r e l , w h e r e water settles out a n d is d r a w n off. A n y p r o d u c e d gas is also d r a w n off.


394


Hamaker Constant I n a d e s c r i p t i o n o f the L o n d o n - v a n d e r W a a l s attrac tive energy b e t w e e n t w o d i s p e r s e d b o d i e s , s u c h as d r o p l e t s , t h e H a m a k e r constant is a p r o p o r t i o n a l i t y constant characteristic o f t h e d r o p l e t c o m p o s i t i o n . It d e p e n d s o n t h e i n t e r n a l a t o m i c p a c k i n g a n d p o l a r i z a b i l i t y o f t h e droplets.


Heater Treater

See T r e a t e r .

Heavy Crude Oil A n a t u r a l l y o c c u r r i n g h y d r o c a r b o n h a v i n g a viscosity less t h a n 10,000 mPa-s at a m b i e n t deposit t e m p e r a t u r e a n d a density b e t w e e n 9 3 4 a n d 1000 k g / m at 15.6 °C. 3

Heterodisperse A c o l l o i d a l d i s p e r s i o n i n w h i c h the d i s p e r s e d species (droplets, particles, etc.) d o n o t a l l have t h e same size. Subcategories are p a u c i d i s p e r s e ( f e w sizes) a n d p o l y d i s p e r s e (many sizes). See also M o n o disperse. Hydrophile-Lipophile Balance (HLB) Scale A n e m p i r i c a l scale cate g o r i z i n g surfactants i n terms o f t h e i r tendencies to b e m o s t l y o i l s o l u b l e o r w a t e r s o l u b l e , h e n c e t h e i r tendencies to p r o m o t e W/O o r O/W e m u l s i o n s , respectively. Hydrophilic A qualitative t e r m r e f e r r i n g to t h e w a t e r - p r e f e r r i n g nature o f a species (atom, m o l e c u l e , d r o p l e t , p a r t i c l e , etc.). I n e m u l s i o n s , h y d r o p h i l i c u s u a l l y means that a species prefers t h e aqueous phase over t h e o i l phase. I n this sense h y d r o p h i l i c has t h e same m e a n i n g as o l e o p h o b i c . Hydrophobic A qualitative t e r m r e f e r r i n g to the w a t e r - a v o i d i n g nature o f a species (atom, m o l e c u l e , d r o p l e t , p a r t i c l e , etc.). I n e m u l s i o n s , h y d r o p h o b i c u s u a l l y means that a species prefers t h e o i l phase over t h e aqueous phase. I n this sense h y d r o p h o b i c has t h e same m e a n i n g as o l e o p h i l i c . Impingement

Separator

See Separator.

Interface T h e b o u n d a r y b e t w e e n t w o phases, sometimes i n c l u d i n g a t h i n layer at t h e b o u n d a r y w i t h i n w h i c h t h e p r o p e r t i e s o f one b u l k phase change over to b e c o m e t h e p r o p e r t i e s o f the o t h e r b u l k phase. Interface Emulsion A n e m u l s i o n o c c u r r i n g b e t w e e n o i l a n d w a t e r phases i n a process separation o r treatment apparatus. S u c h e m u l s i o n s m a y have a h i g h solids content a n d are f r e q u e n t l y v e r y viscous. I n this case t h e t e r m interface is u s e d i n a m a c r o s c o p i c sense a n d refers to a b u l k phase separated b y t w o o t h e r b u l k phases o f h i g h e r a n d l o w e r density. O t h e r terms are c u f f layer, p a d layer, o r rag layer e m u l s i o n s .


395

GLOSSARY

Interfacial

A t h i n layer o f m a t e r i a l p o s i t i o n e d b e t w e e n t w o i m m i s c i

Film

b l e phases, u s u a l l y l i q u i d s , i n w h i c h t h e c o m p o s i t i o n o f the layer is d i f f e r e n t f r o m e i t h e r o f t h e b u l k phases. Interfacial

See S u r f a c e T e n s i o n

Tension

Interfacial

T h e t w o - d i m e n s i o n a l analog o f viscosity

Viscosity

acting

a l o n g t h e i n t e r f a c e b e t w e e n t w o i m m i s c i b l e fluids. It is also c a l l e d surface


viscosity, especially w h e r e o n e fluid is a gas. See also V i s c o s i t y . Internal

Phase

T h e phase i n an e m u l s i o n that is d i s p e r s e d i n t o d r o p l e t s ;

the d i s p e r s e d phase. Intrinsic

F o r e m u l s i o n s , t h e l i m i t , as t h e d i s p e r s e d - p h a s e c o n

Viscosity

c e n t r a t i o n approaches i n f i n i t e d i l u t i o n , o f t h e specific increase i n viscosity, at l o w shear rate, d i v i d e d b y t h e d i s p e r s e d phase c o n c e n t r a t i o n ( [ η ] = l i m ^ c

0

lim^oTisp/C). T h e process b y w h i c h o n e type o f e m u l s i o n is c o n v e r t e d to

Inversion

another, as w h e n a n O / W e m u l s i o n is t r a n s f o r m e d i n t o a W O e m u l s i o n , a n d v i c e versa. Invert-Oil

Mud

A n e m u l s i o n d r i l l i n g fluid (mud) o f the w a t e r - d i s p e r s e d -

i n - o i l (W/O) type, a n d h a v i n g a h i g h w a t e r c o n t e n t . See also D r i l l i n g F l u i d , Oil M u d , Oil-Base M u d . Isoelectric

Point

T h e s o l u t i o n p H f o r w h i c h the e l e c t r o k i n e t i c , o r zeta,

p o t e n t i a l is z e r o . See also P o i n t o f Z e r o C h a r g e . Isokinetic

Sampling

C o l l e c t i n g samples o f a flowing d i s p e r s i o n u s i n g a

m e t h o d i n w h i c h t h e s a m p l i n g v e l o c i t y ( i n the s a m p l i n g p r o b e ) is e q u a l to the u p s t r e a m l o c a l v e l o c i t y . I f these v e l o c i t i e s are n o t t h e same (anisokinetic s a m p l i n g ) t h e n fluid streamlines ahead o f the p r o b e w i l l b e d i s t o r t e d ; c o l l e c t i o n o f particles o r droplets w i l l b e i n f l u e n c e d b y t h e i r i n e r t i a , w h i c h varies w i t h p a r t i c l e size; a n d s a m p l i n g w i l l n o t b e representative. Kinematic

Viscosity

T h e absolute viscosity o f a fluid d i v i d e d b y t h e d e n

sity. Laminar

Flow

A c o n d i t i o n o f flow i n w h i c h a l l e l e m e n t s o f a fluid p a s s i n g

a c e r t a i n p o i n t f o l l o w the same p a t h , o r s t r e a m l i n e . A l s o r e f e r r e d t o as streamline

flow.

Light Crude Oil

A n a t u r a l l y o c c u r r i n g h y d r o c a r b o n h a v i n g a viscosity less


396

EMULSIONS IN T H E PETROLEUM

INDUSTRY

t h a n 10,000 mPa-s at a m b i e n t deposit t e m p e r a t u r e a n d a density less than 934 k g / m at 15.6 °C. 3


Loose Emulsion A p e t r o l e u m i n d u s t r y t e r m f o r a relatively unstable, easyto-break e m u l s i o n , as o p p o s e d t o a m o r e stable, difficult-to-treat e m u l s i o n . See also T i g h t E m u l s i o n . Lower-Phase Microemulsion A microemulsion, with a high water con tent, that is stable w h i l e i n contact w i t h a b u l k o i l phase, a n d i n laboratory t u b e o r bottle tests tends t o b e situated at t h e b o t t o m o f the t u b e , u n d e r neath t h e o i l phase. See also M i c r o e m u l s i o n . Lyophilic

General term referring to the continuous-medium-preferring

nature o f a species. See also H y d r o p h i l i c . Lyophobic

G e n e r a l t e r m r e f e r r i n g to t h e c o n t i n u o u s - m e d i u m - a v o i d i n g

nature o f a species. See also H y d r o p h o b i c . Macroemulsion I n enhanced o i l recovery terminology, the term m a c r o e m u l s i o n is sometimes e m p l o y e d t o i d e n t i f y e m u l s i o n s h a v i n g d r o p l e t sizes greater t h a n some s p e c i f i e d value, a n d sometimes s i m p l y to d i s t i n g u i s h an e m u l s i o n f r o m t h e m i c r o e m u l s i o n o r m i c e l l a r e m u l s i o n types. See also Emulsion. Marangoni Elasticity I n a n e m u l s i o n , a t h i n film o f the c o n t i n u o u s phase is c r e a t e d b e t w e e n two d r o p l e t s closely a p p r o a c h i n g e a c h other. A n y stretch i n g i n this film causes a l o c a l decrease i n t h e i n t e r f a c i a l c o n c e n t r a t i o n o f a d s o r b e d surfactant. T h i s d e c r e a s e d c o n c e n t r a t i o n causes t h e l o c a l i n t e r f a c i a l t e n s i o n t o increase, w h i c h i n t u r n acts i n o p p o s i t i o n to t h e o r i g i n a l s t r e t c h i n g force. W i t h t i m e t h e o r i g i n a l i n t e r f a c i a l c o n c e n t r a t i o n o f surfac tant is restored. T h e t i m e - d e p e n d e n t r e s t o r i n g f o r c e is r e f e r r e d t o as M a r a n g o n i elasticity, o r t h e M a r a n g o n i effect. Metastable Emulsion A system i n w h i c h t h e droplets d o n o t p a r t i c i p a t e i n aggregation, coalescence, o r c r e a m i n g at a significant rate. Micellar Emulsion A n e m u l s i o n that forms spontaneously a n d has ex t r e m e l y s m a l l d r o p l e t sizes ( 1. Primary Oil Recovery T h e first phase o f c r u d e - o i l p r o d u c t i o n , i n w h i c h o i l flows n a t u r a l l y to the w e l l b o r e . See also E n h a n c e d O i l R e c o v e r y , S e c o n dary O i l Recovery. Protection T h e process i n w h i c h a m a t e r i a l adsorbs onto d r o p l e t surfaces a n d t h e r e b y makes a n e m u l s i o n less sensitive to aggregation and/or coales c e n c e , b y a n y o f a n u m b e r o f m e c h a n i s m s . See also Sensitization. Pseudoplastic

A fluid w h o s e viscosity decreases as t h e a p p l i e d shear rate

increases. A l s o t e r m e d shear t h i n n i n g . Rag Layer Emulsion Reduced

Viscosity

See Interface E m u l s i o n . F o r e m u l s i o n s , t h e specific increase i n viscosity d i

v i d e d b y t h e dispersed-phase c o n c e n t r a t i o n (r/

Glossary of Petroleum Emulsion Terms - American Chemical Society

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