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CHEMELECTRIC TREATING

PHASE IN ELECTRICAL DEHYDRATIONOF OIL FIELD EMULSIONS

as presented to

A. I.M. E. SESSION

Liberal, Kansas

November 11, 1963

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on behalf of .

National Tank Company ‘.,

Tulsu, Oklahoma .

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. CHEMELECTRIC TR~ATING

A NEW PHASE IN THE ELECTRICAL DEHYDRATION

OF OIL FIELD EMULSIONS

SUMMARY:

Chemelectric Treating is,a method of treating

oil field emulsions which combines the principles ‘

of electrica I dehydration with the most advanced

variations of the thermo-ch,emical method of treat-

ment. Actually, this is the second phase of appli-

cation of such a combination to the treatment of

oil field emulsions, the first one occurring thirty

or more years ago.

Re-introduction of the method in oil field treat-

ing applications was prompted by three sets of

circumstances, First, under conditions now existing

certain inherent characteristics of electrical de-

hydration offer distinct advantages. This would

include:

a) Ability to treat at relatively low tempera-

tures with resulting savings in fuel and

possibility of improvement of quality and

quantity of stock tank. oil,

b) High adaptability to unattended operation

and remote supervisory control. j

c) High treating capacity which i.. ~kes the

methqd applicable in consolidated tank

batteries, ~

Second, the thermo-chemical portion of the apr -

paratus employes highly efficient design devel~

oped orfly a few years ago, Third, the present

high ~egree of “oil field electrification makes the ~

method applicable in a predominant malority of

treating installations.

The method offers ,an important addition to’. ,the’ practice of treating oil field emulsions. Under

certain conditions, discussed in the paper, its use

“ may be of distinctive economic advantage.

THE PAST AND THE PRESENT . . . RELATED:

The. problem of separating water from produc-

ed crude oil is as old as the Oil industry. itself, In

the early days of the Industry the problem was

-. handled by. settling the free water from od in

open tanks or pits. The intermediate phase be-

tween clean water and clean oil, referred to as

1,.,’.

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“sludge,” was disposed of, usually by burning.

It was not until the turn of the century that at-

tention was called to the fact that “sludge” is an

emulsion of crude oil and” water and that sub-

stantial amounts of merchantable oil can be

recovered from this emulsion.’

The e~tablishment of this fact was followed

by a long period of yJeveloping different methods

and equipment needed to treat crude oil sludges

or emulsions. One of these methods, was electric

dehydration. It was first developed and appliedin the 1910s in California. During the 1920’s the

use of the method spread to other oil producing

parts of the country, particularly to the oil fields

of the Texas-Louisiana Gulf Coast. Introduction,

in the early’ 1930’s of the highly efficient, unitiz-

ed, pressure-operated heater- treater furnished oil

operators with emulsion-treating equipment with

which the electrical dehydration could “not eco-

nomically compete under conditions then existing. :For all practical” purposes electrical dehydrators

disappeared from the oil producing leases east

of the Rocky Mountains in the late 1930’s. In themeantime, electrical dehydration found a wide

application in crude oil desalting and , other

operations within oil refineries. :

The method of electrical dehydration has now

been re-introcfuced as a technique of oil field ~

emulsion treating. It is referred to as ChemelectricTreating., The reasons to be discussed later, wh’ich

Iustify the revival of the method as far as oilproduction is concerned inciude improved equip-

ment, the new manner in. which the process is

offered” to the Industry, and the. changed field

conditions, as co,mpared to those which existedthirty or more years ago. In this,the second phase

of its oil field application, electrical dehydration

is not here to replace present methods O( emuls-

ion treating, but rather to supplement them in ‘

cases.in which it ca”n offer an, economic .advan- .

tage.

At’ the field level, emulsion treating operations.“ ,, ,

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have been routine for many years, For thi~ reason

they are taken for granted. There are many who

do not appreciate sufficiently the fact that the’cost of even very efficient emulsion treating

operations frequently represents an important

pgrtion of the total field operating cost. There-

fore, any new approach which offers promise of

reduction of this cost deserves the attention of.

the Industry.

THE NATURE OF THE EMULSION PROBLEM:

Over the years emulsions have been a su~ect

of extensive scientific studies. Highly complex

theories have been developed regarding the

phenomena involved in forming and breaking of

emulsions. These theories cannot be considered

within the scope of this paper, not even’ in a

summary. It is felt, however, that at least a brief

mention should be made of the basic principles

involved to serve as a background for the dis-

cussion to follow. For those who are interested

in a more detailed study of the. subject two ref-

erences are given. They not only are quite “com-

plete textbooks on the subiect but furnish also

-excellent bibliographies of the rather voluminous

literature on emulsions? ‘

An emulsion is a system of immiscible liquids

in w,hich one liquid is intim~tely dispersed in the

other in the form. of small droplets. The,dispersed

liquid is referred to as the disperse, discontinu-

ous, or internal phase. The other liquid, in which

the first liquid is dispersed, is called the continu-

ous or external phase. Some definitions of emul-

sions include also the factors of minimum size of

the dispersed droplets and of the minimum de-

gree of the emulsions stability,

. . For two immiscible liquids to form an emulsion,’

agitation must exist to disperse one liquid in the

other. For such an einulsiion to become stable,

h~wever, there must be’ presenf in the emulsitsn., still another component; the so-called “emulsify~

ing agent.” This furnishes a film surrounding the

droplets of the disperse phase. The film prevents

the drqp!ets from coalescing into large drops and

the emulsion from bec@ing stratified into layers

of -the two ~~phases C(Sa result of gravitational

separation, While presence of the emulsifying

agent .is a necessary condition for form”ing a

stable emulsion’ the degree bf the emulsion’s sta-

bility depends on a number of other factors:

a) The size of the dispersed droplets.

b) The viscosity of the external phase.

c) The difference in the density of the two

liquids.

d) The volume percentage of the internal

phase in relation to the total volume of

the emulsion.

e) The age of the emulsion.

In the case of oil field emulsions the necessary

agitation is amply provided during the flow of

the produced fluids from the bottom of the well

bore to the surface storage. This is true in the

case of naturally flowing and gas lifted wells

because of the turbulence of flow in tubing and

flow lines and because of passage of the pro-

duced fluids thrqugh different restrictions, such

as for instance, chokes. In the case of pumping

wells the churning action of the components of the

system is the additional contributing cause, par-

ticularly if these components are in a poor state

of repair.

The emulsifying ,agents are associated with the

produced oh’. Since the nature and compositions

of crude oils vary so widbly, there exists also a

great variety of crude oil emulsifying agents.

They include asphaltic matedals, “resinous sub-

stances, soluble organic acids and others. Minute

particles of solids, such as products of corrosion

of the equipment involved or particles of the pro-.

ducing formation, in case of wells completed in

unconsolidcited sands and sandy shales, are also.

the emulsifying agents contributing toward sta-

bility of the emulsions. The agents travel from

the continuous phase to the interface with the

globules of the internal phase and, through the

phenomena of adhesion, they form around those

globules a more or .Iess stable “film. ‘

The type of emulsifying agent determines the

type of emulsion, whether it, is of oil-in.water or.

water-inoil type, There exist also some rather

rare cases of multiple emulsions, such as oil-in-

water in oil emulsions} As far as oil field emul-

sions are concerned, however, the water-in-oil, type is .Predominant. .This is the ,one in -which

water is the disperse ~hase. These are so gen-erally predominant that’ this type is the only one,,

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,...- .—I/ which need be here considered, The agerr!s which

cause this type of emulsion are those which are

preferentially soluble oi dispersible in or’ wet-

table by oil.

THE THEORY BEHIND THE TREATMENT:

The stability of oil field emulsions is an eco-

nomic problem. The more stable the emulsion, the

more difficult, and therefore the more expensive

ii its breaking, necessary to bring the oil to

pipeline specifications for merchantable oil.

Stoke’s Law for rate of sedimentation of a

sphere through a viscous fluid states that this

rate is directly proportional to the square of the

radius of the sphere and to the difference in

densities of the sphere and of the liquid, and is

inversely proportional to the viscosity of the

liquid.’ Since,. in effect, the treating of oil field

emulsions requires sedimentation of water glob-

ules through viscous oil, Stoke’s Law . . . although

its literal application to oil field emulsions is

questioned by some . . . explains the already

mentioned effects of certain factors on the sta-

bility of emulsions. At the same time it suggests

the techniques needed for reducing the tim”e of

“this sedimentation to commercially acceptable

limits.

‘ The effect of the -density differential between

the two phase on stability of emul~ons explains

why. heavy crudes form very stable emulsions,

and why fresh water emulsions are very difficult

to treat. in the first case the gravity differential

between the oil and the water is substantially

reduced. Tke same is true in the second” case

since the specific “gravity of fresh water is lower

~ “ than ‘that of the regular oil field brine;

The, importance of the size of the water drop-

lets, as far as rate of sedimentation is concerned,”

explains certain phenomena of treating of emul-

sions:,

a) The emulsion with a large ‘percentage of

water phase is less stabie and easier to

treat than, the emulsion with a’ small per-

centage of water. This is because in the

case of the large amount of water more

opportunity is-offered the globules to meet;

to collide, and, to coalesce into large drops,

than is the case with a relatively few iso-

lated drops in a large volume of oil and,

b) A fresh emulsion is easier to treat than one

which was given an opportunity to age.

This is due, among other things, to the fact

that if the emulsion is’permitted to stay in

a tank over an extended period of time

some of the water does settle out. The re-

maining droplets are fewer in number thanthey were when the emulsion was fresh and

again less opportunity is available for thqm

to collide and coalesce,’

DESTRUCTION OF EMULSION:

All of the above considerations suggest that

the purpose of any technique for successful treat-

ment of oil field emulsions must be to first destroy

the effects of the film surrounding the water drop-

lets. Second, we must bring abwt their coales-

cence and third we must furnish an opportunity

for undisturbed settling of these drops through

the oil. in the case of certain ctilsthis third stage

of treatment is greatly facilitated by reducing

the oil’s viscosity. The methods which have been

developed to accomplish these o~ectives may

be divided into four groups:

a) Thermal

b) “Chemical

c) Mechanical

1 d) Electrical

In oil field practice a combination of two or more

of thq-above methods i~,,,usuallyemployed.a) ‘7herma/ Methods. The principal effect of ; ! ,

heat in breaking emulsions is the reduction of

the’viscosity of the oil phase. Theories have been

also ‘advanced that heat brings aboui irregular

movements of water droplets within the oil phase,

increasing their opportunity -of, colliding and co-”

a!escing, and, that expansion of water. droplets

as a result of heat, tends to rupture the film sur-

rounding them, particularly in presence of certain

chemical reagents,

Use of heat for treating of emulsions was the .

“first method to find practical application in the

oil fields. in fact, the so-called “sunning” of oil

in “open pits, in the early days of” the IndUstry,has to be considered. d use of a. thertial,.reac!io.m . . .

However, with the degree of heating obtained

by this approach, the best result that could havei? . .,

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been expected was facilitating of settling of free

water and breaking of only the most ynstableemulsions.

Different methods of heating were later em-

ployed in different stages of the evolution of the

art. They included heating with stearn-and-hot-

water-coils immersed in the emulsion and by useof direct and indirect heaters of different designs.

In modern treating practice heat is used almost

exclusively only in combination with other’ meth-

ods of treatment.

b) Chemical Methods. The pioneer of the

method of chemical treatment was William S.Barnickel, a pharmaceutical chemist who, after

the turn of the century, became interested in this

method of approach to treating of oil fieldemulsions. First use of the method was. in the oil

fields of Mid-Continent.

The first chemical reagents used were of the in-

organic type. This was followed by the discovery

of the ability of soaps and their variations to act

as demulsifying agents. The next phase, extending

over the years, included development’ of highly

efficient, complex organic compounds. Literally

hundreds of successful compounds were devel-

oped as indicated by an extensive patent litera-

ture on the su~ect, The use of the compounds is

highly selective. Any given reagent may be very

efficient for one emulsion and entirely ineffective

in case of another one. The selection is primarily

empirical and the well kn~wn “bottle test” is be-

ing extensively used,

Th6 wide variety of reagents ;needed for effec-

tive handling of different emulsions suggests that

the mechanics of the action of the chemical re-

agents on the film surrounding the water droplets

are, complex and cannot be explained by tie

single theory, Several such theories have been

offered. “,

c) Mechanical Mefhod; Breaking qf oil field

emulsions by centrifuging was”in operational use

forty or more years ago: High ‘speeds of rotation

0<17,000 and “more r.p.m. were used. The invest-

ment, and operating costs were high and the

use of the method was”disconfinped.’ At present

e~orts &e made- toward- possible’ renewal” of

application of this method, ,

d) Electrical Methods are considered in more

detail in the following.

THE BEGINNINGS OF ELECTRICAL

DEHYDRATION:

While it does not have direct relation to the

subiect discussed, it should be mentioned,. as a

matter of general interest, that in the year 1600

William Gilbert calied attention to the’ effect of

electrostatic forces on dust particles suspended

in the air.t He ba,sed these findings on his ex-

periments with an amber rod, rubbed with wool,

and smoke from an extinguished candle. In 1661

John Evelyn complained abqut polution of air :

in London by coal smoke. In the second half of

the nineteenth century Oliver Lodge called atten-

tion to the possibility ‘of practical application of

the electrostatic phenomena to “the electrical

clearing of air.” [t was at the beginning of this

century that F. G. Cottrell, then professor of

physical chemistry at the University of California,

performed experiments which formed the foun-

dation of the modern electrical precipitation

industry..

It was F. G. Cottrell ‘who was th~ pioneer of ‘

the process of electrical dehydration of crude oil

emulsions. The basic pafent, issued in the year

191 1; described the experiments in which a thin

layer of emulsified. oil was, spread on glass. Two .thin wires, representing opposite p@SS of’ high f ,

potential sburce” of ‘electricity, were submerged

in the oil. Immediately upon establishing of the :

potential difference it couid be not=d under themicroscope that the water globules formed them- “

selves into chains from one electrode to the

other, an’d that the adioining globules of the

chain “’coalesced into larger drops, The phenom-

enon was explained in the patent as a result of

electrostatic forces acting on the globules of

relatively high conductivity; these gl~bules being ,

submerged in the oil, a non-conductor. The forces

ilwalved are dependent upon the relative, poten-

tials and dielectric :onstatits of the matdrials in ~;

contcict. The advantages of s.dng alternatingcurrent were explained.

The-patent discussedalso qyeral o!hqr- phases,.. . , ,.L

of the:.pr~cess. It”p-oinied out; for- lnita-nce, “that .

if the potential differences becomes too low, “the ~,,

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water globules tend to form permanent chains

between the electrodes. This results in short cir-

cuits, increased power consumption and de-

creases the effectiveness of treating.

The apparatus, covered by the patent, consist-

ed of two vertical, concentric vessels. The outside

vessel, forming one electrode, was connected to

the ground and to the one high-potential terminal

of a step-up transformer. The inner vessel, insu-

lated from the first, was connected to the second

high po?ential terminal of the transformer. The

emuision to’ be treated was introduced tangen-

tially into the top of the annular space between

the two vessels and traveled downward through

the electric field established by, the two elec-

trodes. Large water droplets and oil were taken

out from the bottom of the apparatus and directed

to a settling tank for gravitational separation.

THE BASIC PRINCIPLES EXPLAINED:

Cottreli’s patent was followed during the next

thirty or more years by a surprisingly large num-

ber of patents on electrical dehydration. Exten-

sive laboratory investigations contributed toward

improvements of the’ process and of the equip-

ment involved. Literature was developed covering

the theoretical and practical aspects of the

process. Some of these texts are given as a ref-

erence, All of these studies revealed a fact that

the principles underlying the process of electrical

dehydration, once. considered, very simple, are

actually very complex, and that there are, some

differences of opinion regarding the theoretical

explanation of some of the phenomena involved.

It has been emphasized in the preceding dis-

cussion that brea’king of the emulsion requires:

a) Destruction of the interracial film surround-

ing the droplets and

b) Coalescing of these droplets.

As far” as the first requirement in (a) above is

concerned, it is beiieved that the imposed’ electric

field has the effect of rearranging the polar

molecules of the ‘film. This grea~ly weakens the

film, increasing the probability of its breaking

in case of collision of two er more droplets. It’

has bgen found...gl~olhgtgt t!gre is..a. ce@i!! cfit_

ical tem~erature. below which this phase trcmsi-

tion does mot occur under the influence of the., ,:

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electrical field. This temperature is different for .

different crudes. This explains why it is necessary

in many cases of electric dehydration either to

add heat to the emulsion and/or to depend on

the chemical reagent for breaking of the film. In

the latter case the main role of the electric de-

hydration is to coalesce the water droplets. In

other cases heat and chemical reagents are

added to increase the efficiency” of treating.4 *

Regarding the second requirement in (b) above,

this is assisted by different movements of droplets

imparted to them as a result of the imposition of ,

the elec+ric field, Laboratory studies show that

~with each half cycle of the current the round

water droplets are pulied into ellipsoids and

pulsate in such a way at twice of the current’s

frequency. Further agitation is caused by water

droplets attracting and repelling each other as ,a result of changing potentials imparted to them.

The forces involved are quite high and in collision

of droplets,, rapid coalescence follows. The volt-

age gradient appiied is of importance because in

case of a gradient which is too high actual dis-

persion instead of coalescence could occur! This

would be a result of a large, water drop being

drawn out to the point where its ends would re-

disperse in the form of fine droplets: ‘ ,

The above considerations suggest that design ‘..=

of each of the electrical dehydrati~n installations

requires a. careful consideration’ of all the factors

involved to assure successof operation. The avail- “ .

able large backlog of theoretical investigations ,

and field experience furnishes basis for such

considerations,

ELECTRICAL DEHYDRATION PROVIDES

ADVANTAGES:

ElectriccJ, dehydration enioys two unique ad-

vantages over other, methods of treating of oil

‘ emulsions. One IS abili& to treat oil at relatively

low temperatures, second is the rapidity of co-

alescence of water droplets.

The first advantage satisfies the basic tenet of

treatment of emulsions that such treatment shouldbe performed at the lowest possible temperature

. . . cornpati~le<with satisfactory tr%atinq. W@t? .:@ , . ....- ~fi~h ‘commerc~ally &e-pt&)e’ “m-inimurn-“time of ““

retention. There are &o reasons for this tenet.

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The first, the direct one, is the actual saving in

fuel cost. This is particularly important now when

gas is a valuable commodity, and is true whether

the gas js available or whether it has to be pur-

chased. If the gas is not available and cannot be

purchased, the cost of other fuels may be pro-

hibitively high.

The second reason is indirect, and pertains to

the savings: in gravity and volume of oil as a

result of use of low treating temperature. Curves

A in Figure No. 1 show gravity and volume losses

with ‘increase in temperature in an atmospheric

treating system in which the stream from a 55

psia separator is heated to the treating tempera-

ture in, or enroute to, a wash tank type treating

unit. The data shown in the chart have been ~

calculated for a ,specific crude of known stream

composition. The advantage of ability to treat at

lower temperature, both from the point of view

of income to the prducer and from the conserva-

tion standpoint is quite apparent from the chart.

Actually, savings in. oil gravity and volume

can be attained also in properly designed thermo-

chemical treating installations, operating under”

pressure in which the gas evolved in heating is

condensed and returned” to the treated oil and ‘

proper cooling is provided for the oil ,before it

is flashed into atmospheric storage (Curves B, Fig-

ure No, 1). Saying” of fuel cost, however, is an

advantage unique to the electrical dehydration.

The second advantage, the rapidity of coales- ~

cerfce of water d~oplets is’.illustrated in Figure

No. 2. The photographs in this figure were taken

under microscope with a high speed “mot(on pie-

ture film, Figure 2-A shows the emulsion immedi-

ately prior to the application of the current, Fig-

ure 2-B shows the same emulsions 0,005 sec. after

the voltage was applied. Figure 2-C was taken

1/60 sec. after current application, Translated

into pI actical terms, the rapidity of coalescence,

quite apparent from the photographs, means. a

high freafing capacity; for an electric dehydrati-

ng vessel of “given size under given set of

chndifions..’

f

ECONOMiCS OF ELECTRIC~L’ DEHYDRATION:

hydration was applied under two handicaps.

First was of course the low degree of electrifica-

tion of the oil fields during this period. The sec-

ond reason was economic.

Any well planned control of The co~t of a treat-

ing operation must take into consideration the

per-barrel cost of labor, chemical, fuel, and

depreciation of treating equipment. The per bar-

rel labor and chemical costs are under the con-

trol of the operator. In his attempt to reduce the

overall cost of the treating operations, he can

make an effort to reduce these two co{fs, when

using the thermo-cherhical method of trdatment.

the manner in which electrical dehydration was

fhen offered fo fhe user introduced into this per-

barrel cosf an “additional component which was

fixed and beyond the control of the operator.

Also, the important advantage of electrical de-

hydration, the reduction of fuel cost was during

fhis early period and up until quite recently of

no particular co’r~equence. Gas was an expend-

able cornmodify and fuel cost was frequently not

even considered. [t is not surprising, therefore,

that for field use the electrical ,dehydrafion could

notcompefe with highly efficient fhermo-chemical

freating equipmenf which app~ared in the 1930’s.

The sifuation has now changed considerably,

As stated, fhe fuel cost has bdco~e an important

‘facfor in freating operations. ,E!lectricdehydrators

are sold directly, which ieavtis ‘in the hands of

the; operafor fhe treating cost controi. A new,

additional advantage is the ~acf fhat eiectric

dehydration fits very weii into the present definite

trend toward automation of oii ‘production. Eiec-

tric dehydrators are weii adapfed to unattended

operation and to remote supervision and controi.

Also, because of high treating co~~city of an -

electrical dehydrator it is particularly weii adapt-

ed to use in consolidated fank batteries where

one LACT unit and one treating piant handie

in any given fieid the commingled production of -

ieasps with different royaity accounts. The num-

ber;of this type of batte~es is on a rapid increase.

Because “of the qbove and becuuse of the

inher~nt advantages of electrical dehydration,

theyehqs been a need to re-int~oduce this _mefh,od --

to” the” practice of “’~i ‘-field emulsion”‘treahn~..’ - “. --

.During 1963 the’ efforts in this direction. were.,, .,

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given substantial assistance by combining tbe

elements of the electrical dehydrator with a

highly efficient thermo-chemical treating unit de-

veloped during the past few years, The method

utilizing this new type ‘of a unit is referred to as

Chemelectric Treating.

THE CHEMELECTRIC DEHYDRATOR:

Since the basic principle of treating of oil field

emulsions is separation through gravity separa-tion, it is only natural’ that treating vessels were

and still “are built with the vertical flow pattern

, to assure long vertidal travel for the fluid being

treated. This would include the “hay tanksfl the

“gun barrels” and the ‘conventional, verticalheater-treater. However, it is only in the last

several years that horizontal treaters have beendeveloped, which, with all the advantages of

horizontal vessels, retain the required vertical

flow pattern,

Briefly, the treater of this type is divided into

several chambers. Through each one of them the

fluid is flowing in vertical direction. Ample op-

portunity is provided for degassing of the fluid

I from the moment it enters the first chamber of

the treater, This results in qtiiescent flow of the

fluid through the settling and coalescing cham-

‘ hers, a condition essential to efficient separation.

Large numbers of treaters of this type have been

in use for several years, treating some of the

most difficult emulsions in the oil fields of this

country and abroad.

It is into this type of large volume, vertical

flow pattern, horizontal treater that the’appropri-

“ate elements of an electric dehydrator have been

incorporated, forming what is”called Chemelectric

Treating Unit. Figure No. 3 is the schematic dia-

gram of such a unit.

The qmulsion erttersthe. first chamber from the

top where initial preheating, degassing and sep-

aration of free water’ takes place. It then enters

the second chamber for final heating, more de-

gassing and water separation, The emulsion then

enters the bottom of the third chamber and,

through a spreader, the coalescing space. The. . “con~.entjonal excelsior, pack-i.;. replaced..by two

grid-type electrodes which completely ‘“ill the

cross-sectional areq of the coalescing section.,’

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Clean oil is removed after passing through the

electrodes. Liquid interface control and devices

for safe unattended operation are provided.

220 or 440 vc,lts, 60 cycle, single phase power

is the normal requirement. Transformers are of

the step-up type, with built in internal reactance.

Maximum voltage of the” system is 16,500 volts.

Power consumption depends on a number of

factors, but is generally low. For instance, on

units with 3,000 barrels per day capacity, daily

power costs have been reported to be from $0.25

to $1.00 per day.

Cost data have been presented on three instal-

lations in which thermo-chemical treating was

replaced by Chemelectdc units.6Savings in treat-

ing costs were substantial, ranging up to $104

per day for one installation. They were brought

about -by savings in fuel consumption ranging

from 50 to 61 percent, because of lower treating

temperatures used, and by improvement in grav-

ity and increased volume ,of the stock tank oil.

Chemelect~c ‘ nits of design here described

rhave been in ac iJal field operation only a year

or so. The prelirn~iary reports are very encour-

aging. For instance, one of these units replaced

in Oklahoma a heater-treater, in an installation

handling 45 bbls./hr. of oil of 22° API of asphal-

tic base and emulsion. Fuel consurnpfion of the

installation has been r,educed from 70 to less

than 30 MCF per day by use of the Chemelectric

Unit.

APPLICATION CONSIDERATIONS;

It has been stated in this paper that electrical

dehydration is here not to replace but to supple-

ment the conventional treating under appropriateconditions, Discussion of the method presented in

this paper suggests the conditions under which

the method would be particularly applicable. In

working out the preliminary economics both the. expected savings and the initial ,cost of Chem-

electric Unit compared with conventional treater

of equivalent capacity have to be taken ‘into con-

sideration. Conditions particularly favorable for

Chemelectric Treating would be as follows:

1) _Any case ifl which the cost of, _fbeI may—.-. +. ...- .. ... .become excessive either ‘because”&f ‘loss of- ‘” ‘“-”

/ gas for which market is available, or be- ,,’

, ,,

r f 3,,

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2)

3)

cause of need for purchase of gas or

other fuel. ,

Cases in which reduced treating tempera- 4)

tures may result in improvement in quality

and quantity of stock tank oil.

Cases in which sand or solids in the pro-

.-

ch.reed fluid result in operating problems

with conventional excelsior pack. .

Certain cases of automated leases, and

most cases of consolidated tank batteries,

where high capacity treating equipment is

required.

I l~Hi~tory of petroleum Engineering” AmericanP@trOleunlInstitute,Division of Production, 1961.

z ~~~mul~ion~ Theory and Practice#” Paul Becher, Ameri-can Chemical Society Monograph Series, Reinhold Pub-lishing Corp., New York, 19571

~l~c[ayton~s, The Theory of Emulsions and

nical Treatment,” C. G. Sumner, Fifth EditionChurchili Ltd. London.

dI/The Technology Of Resoiving petroieim

Louis T. Monson and Richard W. Stenzei,Chemistry” Jerome ~iexander Ed, Voi, Vi,New Yark, 1946.

Their Tech-‘i954, J & A

Emulsions,”in “CoiloidReinhoid –

5“Correlation of Factors Affecting the Gravity Separationof Crude Oii-Water Mixtures~’ J. M, Campbeii and J. L,Johnston. A paper presented before the Mcirch 1957

f

REFERENCES

,’

Daiias, Texas meetingof the SouthwesternDistrictAPiDivision of prodvctiorr.

~//The origins of Eiecfricai Precipitation,” Myron RObin-son, “Eiectricai Engineering” September, 1963.

r F. G. Cottreil and J. B. Speed, U.S. Patent 987,1 T5March 21, 1911.

e“Chemicai-Electr/cai Dehydration Pracessfl H. R. Jarvisand J. R. Moecheil. A paper presented during the West -Texas Oii Lifting Short Course, Lubbock, Texas, Aprii1962.

9 //The Role of ~iectrostatic Precipitation in the ResoiufiOn

of lnd&triai Emulsions,” R. W. Stenzei and W. F. Eberz.A paper presented before the Division of PetroieumChemistry American Chemicai Society, New York, ,Sep-tember 1960.

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COMPARATIVE RECOVERIES AND GRAVITIES-

FOR VARIOUS TREATING COMPONENT ARRANGEMENTSco-1wmaem 96C

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