CA1287543C - One-step process for transforming a water-in-oil emulsion into an oil-in-water emulsion - Google Patents
One-step process for transforming a water-in-oil emulsion into an oil-in-water emulsionInfo
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- CA1287543C CA1287543C CA000517675A CA517675A CA1287543C CA 1287543 C CA1287543 C CA 1287543C CA 000517675 A CA000517675 A CA 000517675A CA 517675 A CA517675 A CA 517675A CA 1287543 C CA1287543 C CA 1287543C
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- water
- oil
- emulsion
- emulsifier
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Abstract
ONE-STEP PROCESS FOR TRANSFORMING A WATER-IN-OIL
EMULSION INTO AN OIL-IN-WATER EMULSION
Abstract of the Disclosure There is provided a process for the formulation of an oil-in-water emulsion from a produced hydrocarbon crude which includes a water-in-oil emulsion. A surface-active chemical system is added with agitation to the crude when such crude is at a temperature of from about 100° to about 200°F, in a quantity sufficient to formulate and then sus-tain an oil-in-water emulsion at pipeline conditions of temperature and shear. Water-content is from about 15 percent to about 35 percent by weight. Viscosity is sufficiently low for pipeline transportation. Any excess water is separated from the formed oil-in-water emulsion prior to pipelining. The oil-in-water emulsion is one that can easily be dewatered and desalted to the neces-sary marketing specifications at the downstream end of the pipeline, using known technology.
EMULSION INTO AN OIL-IN-WATER EMULSION
Abstract of the Disclosure There is provided a process for the formulation of an oil-in-water emulsion from a produced hydrocarbon crude which includes a water-in-oil emulsion. A surface-active chemical system is added with agitation to the crude when such crude is at a temperature of from about 100° to about 200°F, in a quantity sufficient to formulate and then sus-tain an oil-in-water emulsion at pipeline conditions of temperature and shear. Water-content is from about 15 percent to about 35 percent by weight. Viscosity is sufficiently low for pipeline transportation. Any excess water is separated from the formed oil-in-water emulsion prior to pipelining. The oil-in-water emulsion is one that can easily be dewatered and desalted to the neces-sary marketing specifications at the downstream end of the pipeline, using known technology.
Description
~;~87S~3 16810:JPG:256 -1-ONE-STEP PROCESS FOR TRANSFORMING A WATER-IN-OIL
. EMULSION INTO AN OIL-IN-W~TER EHULSION
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Produced crude oil:~in~he field can have substantial quantlties~of~:water associated witb it. The water-cut or 20~ amount~of~water~associated with the oil can be as high as~ 95~:of the~ total~produced~ stream. This is especiall~ ~
true:~in heavy~oil~fiel:ds~where the;oil is being produced ~ -from reservoir~s):~ha~ing a~trong water drive. Usually, the:he:avy oil:~its~elf~ s so:vlscous at ambient tempera-25 :~tures~that it ~requlres:tremendous~pumpi~ng ener~y to wake it flow, if~ at all. ~me:water present ~n the produced stre;am:~c~a:n~be cl:assified:~into two categories: "bound"
water~and~-:fr;ee~ water~ ound"~water is~that water .
wh~ch~is~locked~up:~in~the oil as a water-in-oiI (W/O) emuls~ion.~ Separati`n~ this~water from the stream typi-cally~requires~:applying the appropriate combination of ;heat~ m~ix~in~and~a ch~emicàl demulsifier. "Free" water s~that~wate~r~:~which i~s rèlatively loosely held u~ by the ::oi:l~and~c~an be:~r~emoved: just by heatin~ the stream to the rlght~temp:erature. ~
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~2~37S~3 1 The above-mentioned produced water~in-oil ~W/O) emulsions usually have a higher viscosity than the dry oil which itself is very viscous. This high viscosity frequently limits the rate at which the W/O emulsion, and S hence the oil contained in it, can be pumped up a well-bore or through a pipeline. One method for handling this problem has been to formulate an oil-in~water (O/W) emulsion of the oil. Oil-in-water ~mulsions usually have a lower viscosity than the oil itself and ~o the oil in this form can be pumped at faster rates. Crude oil-in-water emuls$ons have been formulated in one of two ways:
One ap~roach has been to take the produced stream from the wellbore and separate out the water by subject-ing it to a combination of heat, mixing and at least one chemical demulsifier in a heater-treater. The ~dry" oil stream which may contain anywhere from 1-52 water by weight is then ~ixed with the right Emount of water and a chemical emulsifyin~agent to form a low viscosity, trans-portable oil-in-water~emulsion. me amount of water used is governed~by~the need~to obtain a low viscosity trans-port fluid and to~maximize the oil throughput. Normally, a transport O/W emulsion contains from about 15% to about 35~ water by weight.;
The other approach has been to attempt to fnrm an oil-in-water~emulsion within the well~ore itself. Water ~containing one or more emulsifying agentts) is usually ~added~either~down the annulus or the tubin~ to contact the~o~il and~water com~ing from the formation into the well-bore~before or as they enter the downhole pump. In this ~30~ way~ an~ O/W~emulsion of the crude is formed as the fluids pass~;thro~ugh~the downhole~pump. This downhole attempt at ~forminq~O/W~emul~sions presents considerable operational diffi~culties.~ Each well behaves independently of any ` ~ other~well.~; mere~are presented, therefore, a number ;35 of operational variables from well to well which must be ' , .,~
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75'~3 1 constantly combatted if a sultable O/W emulsion is to be formed. More serious is that, in order to produce the oil to ehe surface, it is necessary to use some artificial liftin~ device, and where water content is hi~h, energy requirements for the lifting devices are also high. m is will affect the chemical dosage used. For example, in the case of heavy oil wells with high water cuts wherein enormous amounts of total fluid (oil plus water) have to be lifted to get reasonable oil production rates, it is becoming common to use electrical 6ubmersible pumps (ESP) which can pump out these fluids at tremendous rates. The or~mation of an O/W emulsion is determined by the tempera-t~re, chemical emulsifier dosage and degree of shear or mixing. In a well using an ESP which generates a lot of shear~, an;excessive amount o~ chemical may be required to successfully formulate, if at all, an O/W emulsion.
~According to this invention, there is provided a method for fo m ulating a pipeline-transportable crude oil-in-water (o/W) emulsion by taking the output of one ~or~more crude oil~field~ well(s) and directl~ inverting the produced stream of a water~in-oil~(W/O) emulsion and "free" water, if any. The~formulated O/W emulsion con-~ tains~from~about lS%~to 35%~ by weight of water and hasthe~necessary low viscosity and stability to withstand ~long pipelining~periods~ and any pipeline shut-downs and Btart-ups:. ~ me~ ~o/w emulsion can easily be dewatered and ~de~sal~ted to the~necessa~ry marketing specifications at the ; ~30~ downst~rèam énd~of the pipeline, usin~ known technnology.
The met~hod involvcs usin~ one or more surface-active ` ` ~age~nt(s) and agitation at temperatures ranging from about 100~DF~to~about~200F to invert the produced W/O emulsion and~'lfree" water~in one process step to for~ the O/W
~emulsion. ~The~ purpose is to coalesce all the water :
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~ 87S~3 agent(s) and agitation at temperatures ranging from about 100F to about 200F to invert the produced W/O emulsion and "free" water in one process step to form the O/W
emulsion. The purpo~e ix to coalesce all the water contained in the produced stream of the W/0 emulsion and the "free" water into one continuous phase and simulta-neously disperse the oil in the form of small droplets in this continuous water phase.
There may be employed a ~ingle ~urface-active agent (emulsifier) if it is capable of forming and then sustaining the emulsion over a broad temperature range. A
mixture of surface-active agents may be desirably (emulsifier) employed. Depending on emulsifier, concen-tration may range from about 100 to about 5,000 ppm by weight, of the crude. Where the as-produced W/O emulsion is of high water-content, e.g., about 50% or more water, the amount of emulsifier employed is just sufficient to stabilize an O/W emulsion at a 15% to 35% water-content.
That water which is unnecessary to sustain the O/W
emulsion is allowed to separate from the O/W emulsion prior to introduction of the O/W emul~ion, at the desired water content, into a pipeline. Conversely, when the crude contains les3 water than i required to form a low-viscosity transportable O/W emulsion, water can be added to the W/O emulsion prior to or during transformation into the O/W emul~ion suitable for pipeline transportation.
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12~ 3 The invention is illustrated, by way of example, in the drawings, in which:
Figure 1 illustrates the presently preferred system for practice of the invention;
Figure 2 illustrates in block diagraml the two sequences for forming O/W emulsions in accordance with the invention.
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1;2~37543 The invention is directed towards formulati~g pipeline-transportable oil-in-water (~/W) emulsions by directly inverting a produced stream of a water-in-oil (W/0) emulsion with or without ~free" water, with the aid of an emulsifier ~surface-active chemical), nonmally a mixture of emulsifiers. Furthermore, the invention is also directed towards controllin~ the characteristics of the 0/W emulsion such that it is suitable for pipelining over long distances, e.g., the viscosity, water-content and stability of the emulsion. m e formulated 0/W
emulsion should be easily dewatered and d~esalted ~o the necessary marketing s~ecifications at the downstream end of the pipeline, using known technoloqy.
With reference to lIGS. 1 and 2, (the invention can be generalized~by considering a set of production wells in a heavy~oil field~where~the oil is~being produced from a ~ reservo~r~having a~strong water-drive. Consider that the water-cuts are high and that the welIs have the appropri-ate~artificlal lift syst~ems, e.~., electrical submersible pumps.~ me production streams~from the individual wells are taken~to~a central~point above the ground, where they are commingled.~ However`,~it should~be~ noted that the method~of~for~ulating~ the 0/W emulsion in accordance with the;inven~tîon~can be~carried out at an individual well-head~ At;~this c~entral locatio~n, the co~mingled production ~stream~will~usua~lly cons~îst of the following components:
à~W/~O~emul`sion~ n~free" water, and some associated gas ~îf 0~ anY)~ For~illustrative; purposes,~ we~will assume that ~these~wélls~have~low-producing qas-oil ratîos.
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The~water~present~in the produced stream can be c~lass~iied~ into~two~categories: "bound" water and "free"
~water. nBound~" water is that water which is locked up as a~W/0 emul~sion~ Separating this water from the strea~
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~287S9~3 1~10 _7_ 1 t~pically requires applying the appropriate combination of heat, mixing and chemical additive(s). ~Frse" water is that water which is relatively loosely held up by the oil and can be removed just by heating the stream to the right tem~erature. The amount of "free" water which can be removed will de~end upon the temperature to which the stream is heatedO
This mixture of produced W/o emulsion, "free" water and associsted gas, if any, is fed into a heated vessel, where a certain portion of the ~free" water may be dropped out, with separation of most, ~f not all, of the associated gas. me effluent from this vessel i5 then mixed with an appropriate concentration of an emulsifier, and is fed into an emulsification unit. Alternatively, depending upon the equipment available at the site, the stream may be fed directly to the emulsification unit without any "free" water separation.
e emulsification unit is e~uipped with a heatin~
; unit and a mixer. In the emulsification unit, the idea is to use thP emulsifier at the appropriate temperature, shear to coalesce substantially all the water (~boundn and "freen) present in the incomin~ stream into one con-tinuous phase, and simultaneously disperse the oil phase in the form of small dropIets in this newly-formed con-25 ~ tinuous water phase. The objective is to essentiallyinvert the stream of the W/0 emulsion and "free" water ~into~a~water-external 0/W emulsion. me degree of inver-sion sough;t is~close to~ 100~. The produced W/0 emulsion and~"free'i water mixture is essentially transformed into ~an O~W~;emulsion~in one step. The concentration and the nature~of the~emulsifier are chosen for the ability to achieve the~required deqree of inversion and also bind ; up and stabiIize only that amount of water in the newly-3~ ~
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~L2~7S ~3 16B10 _~_ 1 formed O/W emulsion as is necessary to obtain a low enough viscosity from a pipelining standpoint. Any extra water will be loosely bound and should separate out easily in a quiescent storage vessel.
The O~W emulsion containing excess water (over what is required from a pipelinin~ standpoint) is then fed into a large ~torage vessel, where i~ has enough xesidence time in a quiescent environment, so that the excess water that was not bound up by the emulsifier drops to the bottom of the vessel and can be drained out. In addition to con-taining the pro~er amount of water, the O/W emulsion should contain ~ust enough emulsiier to maintain its stability over long pipelining periods and withstand any pipeline shutdowns and startups. Finally, the emulsion is one that can be easily dewatered and desalted to the necessary marketing specifications at the downstream end of the pi~eline, using known methods and technology.
With specific reference to FIG. l, there is shown a schematic of a typical~facility for applying the invention in the field. The solid lines show equipment essential to the practice of the invention, and dashed lines indicate optional;equipment. Production from a series of producing wells is introduced via flowlines 10, 12 and 14 to a com-mon manifold 16. The commin~led production cominq into the common manifold will be a mixture of a W/~ emulsion, "free" wa;ter and some associated gas, if any. me produc-tion; from ~any well can be fed by manipulation of ~ate valves l8~and 20,~either;to the test facility for gau~ing ~the~oi~l~production rate and the water-content of the strea~, or directly throu~h line 24 to the "free" water knock-out unit ~FWKO) 26, which is an optional piece of ~equi;pment. ~
~ The~FWKO is operated under pressure and has a heat-ing unit~30 in it which allows the process strea~ to be heated to any pre-set temperature within the unit desi~n :
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~Z87S~3 l6sln _9 -1 constraints. This temperature is s0t at the level needed to formulate the O/W emulsion. In the FWK~ unit, depend-in~ upon the tem~erature, a portion, if not all, of the "free" water will drop out of the stream and can be drained off from the bottom throu~h line 32 to the water supply tank 34, which is also optional. The water from this tank can be used, if necessary, employin~ control system 36 to increase the water-content of the FWKO
effluent. Most of the co~produced gas should ~eparate out in the FWKO and is vented through valve 28 to the flare. The FWRO effluent is essentially a mixture of a W/O emulsion and residual "free" water, if any.
If the initial system for separatin~ out the "free"
water and/or heating the stream is not employed, all the equivalent steps may be employed in emulsification unit 51. IndeDendent of whether or not an optional system for water separation and/or heating of the stream for proper for~ation of an O/W emulsion is employed, the feed metered `by meter 3R with a~ cut ~onitor and a sampler, is combined with th~ ~roper~amount of the emulsifier from stora~e uni~t 40. The emulaifying a~ent is pumped out of the tank throu~h line 46~via a flow rate meter 44 and is combined with~the a.s-produced or preprocessed stream. The mix is passed~;through an in-line mixer 50 to the e~ulsification unit 51.~ The~emulsification a~nit has a heating unit;S4 and~an ag~itator 52, wh~ich is a back-up to the in-line mixer~and is optional.~ The objective in this unit is to coalesce~all the~water present in the feed stream as a W/O
~ ~emulsion and~as~"free~" water into one oontinuous phase and ~simùltaneously disperse all the oil in the form of small ~droplets in this con~inuous water Dhase. The idea is to ~invert~the~water-in-oil emulsion and "free" water into an oil-~in-water~emi~lsion in one ste~. The de~ree of inver-~ ~ sion souqht is 100~. me emulsion is formed at a tempera-35~ ture of~from~ahout 100 to about 20nF, preferably from ::
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12~37Si'~3 16~10 -10-1 about 130 to about 17UF. The amount of emulsifier used may ran~e from about 100 to about 5,000 ppm weight-to-weight o~ the hydrocarbon crude, typically from about 500 to about 2,50~ ppm by weight, desirably from about 700 to about 1,0~0 ppm by weight-to-weight.
The actual water-content of the W/O emulsion initially processed at this ~age may vary widely: It may contain up to 95% by volume water, or it may be a relatively dry oil containing less than the amount of water reguired to form a low-viscosity O/W emulsion tha~ is pipeline-pumpable. The object is to provide an O/W emulsion containing from about }5% to a~out 35~ by weight waterr preferably ~rom about 20%
to about 30% by weight water. To this end, tank 34 is used to proYide water externally derived and stored or recovered lS from the as-received wellhead production stream by separa-tion~in unit~26~to ad]ust~the water-content of the O/W
emulsion for it to have an optimum viscosity for pipeline ; pumping. Consequently, the omount of emulsifier added ~` from unit 40 is~oontrolled so as to form a stable O/W
~ emulsion of~a water concentration suited far low-viscosity pipeline pumping~ Any extra water will be loosely bound and~should separate easl~ly~on~keeping the stream quiescent.
~Excess emulsifier is,~therefore, to be avoided in order to prevent the~binding up and inclusion o~ too much water ~;in the~0/W;~emulslon and~lncrease thereby, despite low viscosity, energy requirements for transportation, or to preclude the introduction of too little emulsifier su~ch;~that,;~al~though there~is formed an initial complete O/W~;emulsion,~the amount of emulsifier present is too 30~ ;little~to~s~usta~in~the emulsion at an ambient-temperature v~iscosity level suitable~for pipeline transportation.
The effl~uent of;~the emulsification unit should essen~t~ially be~a~wate~r-external, O/~7 emulsion~ However, ~ ~this~O/W~emulsion may contain quite a bit of extra water ~rel~atlve~to~that required to achieve a certain pipeline :
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~Z~S~3 I viscosity. This effluent goes through a sampler 56 whereby the guality of the inversion achieved, can bs checked. If needed, it can be recycled through line 5~
and tank 53 back to the emulsification unit 51 to ensure formation of a proper o/w emulsion. me pro~erly formed o/W emulsion goes through a degassing boot 64 into ~he shipping tank 72. In the ~hipping tank the objective is to have enough residence time in a quiescent enough environment such that all of the extra water will settle down to the bottom of the tank so that the effluent 0/W
emulsion will contain the right amount of water necessary f~om a pipeline-viscosity standpoint. me extra water sett}ing to the bottom of t~nk 72 can be drained off to the sump. me quality of the oil-in-water e~ulsion is checked~by another meter with a cut monitor and sampler ?0 and, if satisfactory, it is sent to pipeline 80 for transportation to the desired destination.
If the effluent 0/W emulsion from the tank 72 is not suitable for pipel~ining, it can be recycled through line 76 and tank 82, back into shippin~ tank 72 or, if neces-sary, through line 66 back to the emulsification unit.
At this point, it should be noted that as long as thc amount of water in the effluent 0/W emulsion is ~reater than~what is needed, there should be no problem from a 25 ~ pipeline-viscosity standpoint. However, the excess can-not be too large because there may be limitations in the pi~eline~from a pumping-capacity standpoint. There will definitely be a problem if the amount of water in the ~;e~ffluent 0/W emulsion~is less than what is required from - 30 an~effective~pipeline-viscosity standpoint.
As indicated, in the practice of the invention the objective is to~take a produced stream of a mixture of water-in-oil emulsion and "free" water; optionally drop out a~portion o~ the "~free" water, if necessary, or add 3~ some water as the case may be; mix the remaining stream :
~2~7~3 with the appropriate concentration of an emulsifying agent ~mixture of surface-active chemicals); and then invert the same into an oil-in-water emulsion in one step. The idea is to coale~ce all the water present in the feed stream a~
a W/0 emulsion and as "free" water into one continuous phase, and simultaneously disperse all the oil in the foxm of small droplets in the newly-formed continuous water phase. The concentration of the emul ifier used is tailored such that during the procesR of inversion the amount of water which is bound up strongly in the oil-in--water emul~ion will be very clo~e to what is required from a viscosity standpoint. Any extra water, as opposed to "free" water, which i~ loo~ely held up in the oil-in-water emulsion is then removed by pas~ing it through a quie~cent storage unit and the effluent stream iR transportéd through the pipeline.
All supplying systems used to form the 0/W emul~ions are catered to the effluent of the wells. Generally, unless a broad-based emulsifying agent is used, a mixture of at least two emul~ifying agents is employed. Surface -active agents used to form 0/W emulsions may be anionic, `~ cationic, nonionic, amphoteric, and the like. A desired and preferred characteristic is a high degree of oil insolubility. Preferably, the surface active agents are substantially insoluble in oil. Mo~t of the inexpensive and efficient candidate~ for forming crude 0/W emulsion are either anionic or nonionic. Nonionic~ are presently preferred because they are generally cheaper and not ~affected by the salinity of the water.
The be t known of all the anionic-active emulsifying agents~are the soap~ which are the salts of the long chain fatty acids,~derived from naturally occurring fats and oils, in which the acids are found as triglycerides. The soaps used as emul~ifying agents may be obtained from natural oil~, in which ca~e they will consist of a mixture : :
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121~7~3 1 of fatty acids, the precise nature of the mixture depend-ing on the fat or oil employed. The mixed fatty acids o~
tallow, coconut oil, palm oil, and the like, are those commonly employed. The acids derived fro~ tallow, for instance, may be partially separated by filtration or by pressing into "red oil" tprincipally oleic acid) and the the so-called 'Istearic acid" of commerce, which is sold as single-, double-, or triple-pressed, depending on the exten~ to which oleic acid is separated. Such stearic acid is actually a mixture of stearic and palmitic acids.
The nonionic surface-active agents can be classified into five~types, namely, ether linkage, ester linkage, amide linkage, miscellaneous linkages, and multiple linkage. ~he preferred nonionic emulsifiers are selected ~from the compoùnds having the general formula:
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, R ~ O - tCH2CH2O)nH
and ~ R
x ~ o - ~ CH2CH20 ) nH
~ where~R~Is~any hydrocarbon group and n is the number of~
25 ~ ~poIyGxethyIene~groups ranging`~rom about 4 to about 100, ;preferab~ly about 30 to about'7100, and substantially oil ~insoluble.
The most prominent members o this class are those campounds~ formed by the reaction of a hydrophobic ~30~ hydroxyI-sonta~Inlng compound, e.g., an alcohol or phenol, with~et~hylene oxide, or, to a lesser extent, propylene oxlde.~ ~The ethyle~ne oxide groups, for example, may be added~to a~ny~d;esi~red extent.~
Nonlonic~surface-active agents hav~ins an ester link-35 ~ ~age~include~compounds of the following general formula:
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~Z8~S~3 R - C - 0 - (CH2CH20~nH
where R and n are as defined above.
The esters formed by the reaction of the fatty acid with polyhydric alcohols are a particularly interesting group of nonionic emulsifiers, in that, depending on the nature of the alcohol used, they may be predominantly hydrophilic and are especially suitable as 0/W emulsiiers.
An example of an ester-linkage surfactant which is a good emulsifier i5:
; C17H35 - C - 0 - (CH2cH20)5oH
;~ The presently.preferred ester linkage surfactants are of the formula~
CgHlg ~ 0 - (CH2CH2oj~
;wherein~y~is from~abou~t~9 to about 100 wlth at least a :: . :port:ion of:the agent;:being compounds wherein y is at : l~east~about~40 to ensure a~subs:tantial:degree of oil insolubllity.~
~Z5~ Nonionic emulsifiers with~amide linkages are com-pounds of~:the~ge~ner~al formula:
(CH2CH20)nH
~ \ (CH2CH20)nH
~ wher~e~R and~n are~as defined~above.
u~ Th~e~emul~s1fier~system~used in the practice of the invention~;must enable:formation of the Q/W emulsion at 35~ e~1evat:ed temperatures~and retention of stability at JL;Z ~7S ~;~
1681~ -15-1 smbient temperatures. Unless broad-based ~or ~uch func-tionality, a mixture o~ two or more emulsifiers is employed, and is particularly preferred.
There are several advantages for applying the inven-tion for formulating oil-in-water emulsions in the field:
a) It would be particularly useful in the initial stages of developing a new field or in a ~ield where there are only about one or two wells and it is not economical to construct a large production ~acility. In such instances, the invention reduces the number and the size of the mechanical facilities to be installed. This is because inverting in one stage the mixture of the pro-duced W~O emulsion and the ~frée" water, if any, elimi-nates the need to have one unit for demulsification and one unit for emulsification. As mentioned earlier, the process may;be op~imized by separating, i~ necessary, some~ of the "free" water out of the produced stream :
before making the emuIsion; however, this is not essen-~tial.;~Por e~x~ample, in a~new flçld where there is no ~roduction facility, the total stream of the produced W/0 emuls~lon~and;all~the "~ree' water can be inverted into an O/W em~ulsion in~one stage. There would be~employed an ~ppropriate concentration of the right emulsifier mixture to bind~up only that porti~on of the water required for obtaining the~effective;viscosity needed for pipelining.
Broad~ly speak~ing, applying the invention would really ~involve h~a~vlng a mixing device, an emulsification unit, and~a~aettllng ta~nk~for~dropping off the excess water.
th~is new~field is~close to an existing field with a 30~; 1a~rge~production~faci}ity, the 0/W emulsion containing excess~-water can be injected directly into a short pipe-~line~to~this~;neighboring facility. In this event, the settling tank can be eliminated.
In~summary~,~ o~rmulatlng an 0/W emulsion by this 3S ~method~can~potentially decrease the capital cost o~ a :
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~2~ 3 1 production facility to be installed in a new heavy-oil field. Furthermore, since the produced stream is not demulsified first, it can also potentially reduce the chemical cost.
b) If the wells have high water-cuts, there will be a lot of co-produced water. Using the co-produced - water to form the emulsion will alleviate the water-disposal problem.
c) It has been observed during pipelining of an O/W emulsion formulated by mixing water and an emulsifying agent with a dried oil stream, that some of the water is transferred from the external, continuous phase into the oil drop}ets. This can, depending upon the extent of the water lost to the oil, increase the effective viscosity of the O/W emulsion, which can lead to problcms if it is necessary to stop and restart the pipeline. The amount of water lost to~the oil during the transport o~ the O/W
emulsion~is less if the oil is not treated and dried ~ bef~ore it is emulsified. Hence, formulating an O/W
emulsion by invert1ng~the produced W/O emulsion in one step, as outlined in the; invention, would be better for long-dlstance pipeline~applications.
~ Without limiting,~the following Examples illustrate, the 1nstant Invention in part.
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Example 1 The~o11 samples used for these investigations were rom~;the~Jibaro Fi~eld in the Peru Oriente, and were pro-; v1ded;~i~n 5-gallon~containers. Karl Fisher water analyses 30~ ;were~performed, revea1ing that the four samples each con-~tai;ne~d~514, plus or minus 2%, total water. The samples we~re~heated to~65C ~149F) for 4 hours, and any "free"
water~that~separated out, was removed. Only 2% of the ~water~in~ the~sampIes dropped out on heating to this ~temperatu~re. The~warm W/O emulsion was then mixed with . :; ~ :
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128~S'~3 the appropriate amount of emulsifier in a mixer. Mixin~
energies and times were kept to a minimum. The O/U emul-sions formed were then allowed to stand for 30 minutes and viscosities were measured. ~mulsifier was added, either directly to the W/O emulsion or dissolved in 5 weight-percent produced water which had been separately made available. The emulsifying agent was a mixture of two surface-active chemicals, manufactured and sold by Tetrolite, of St. Louis, MO, a division of Petrolite Corporation. The reversal of emulsion phases was found ~o be more delicate than emulsifying relatively dry oil into water. Adding demulsifier to the W/O emulsion such that some water was dropped out before Adding the emulsi-fier, did not appear to be as effective as operating on the provided W/O emulsion, in that the system was very limited in allowable temperatures, mixing times and treating rates.
The results of forming O/W emulsions by directly inverting the produced ~l/O emulsions at an emulsifier concentration~of~2,000ppm, based on the weight of the treated W/O emulsion, are~shown in Tables I and II.
Table I
~ 70F Viscosity vs._Shear Rate : : ;
;~ As-Formed Shear Rate sec.~l Viscosity, cp 200 ~ 22 600 ~ 18 1 0 0 0 :~
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~2~7S~3 ' Table II
70~ Viscosity vs. Shear Rate Upper Phase after Water Separation Shear Rate sec.-l Viscosity, cp .
10 400 1~0 Stability~of the O/U emulsions was measured by allow-ing the emulsions to s~and quiescent~ overnight. About 24 by~volume extra water dropped out. This indicates that the~upper emulsifled pbase contained about 33~ water by volume.~ Based on this information, it is believed fea-sible to invert, in one step, a ~/O emulsion containin~
~50% or more~water using from 1000 to 2000 ppm o~ the emul-~si~fl~er,~based~on the weight of the tre;ted~/O emulsion.
~The;stability of~these~emulsions is such that, from 25%~
to 35%~wa~ter~is indefinitely stable. ~ased on viscosity ~;datà,~ it~ s~es;timated~that the upper-phase emulsion, wh~ch contains a nominal 33~ water, actually contains from about -~28%~to~30%~wat~er as a~continuous phase and from 3% to 5%
wate~ as~dlspersed~droplets.
~30 ~ Example 2 Add1ti~onal~studles were~ performed using another batch o~producéd Jibaro~W/O;~emul ion containing 50% water. The sa~pl~e~bad~been~in storage for several months after being collected~ n the;fle~ld~and was old. No water had dropped :
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The emulsifiers u~ed in the testing series were the ethoxylated nonylphenols. They are all members of the general family of nonionic ~urface active agents of the formula:
C9Hl9 ~ 0 - (CH2CH20)yH
The ethoxylated nonylphenols ~NP series) are characterized by y = 4-100.
The following member~ of the NP family were tested:
NP No. y The required emulsifier concentration was found to depend strongly on the age of the produced W/0 emulsion, the emulsification temperature and the mixing efficiency.
In using an old W/0 emul ion sample, only qualitative trends can be drawn about the behaviour of the system3 te~ted.
All the te ts were conducted by shearing the mixture of the W/0 emulslon and the added emulsifier using a rotor- tator mixing device. In some ca~es, a small dose of a demuls~ifying agent,~also produced by Tretolite, was added along with the emulsifier. The rotor-stator gap and the speed were adju~ted to generate about 10-4 sec-l of ~` 30 ~hear. Each mixture was ~heared at this ~ame rate for about~40 seconds. No attempt was made to vary the manner ln~whlch the~shear was~applied. After shearing, the resulting mixture was stored under quiescent condition~
~for~about 24 hours. It was then evaluated to determine 3S whether it ,~ ' , :
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~LZi~7S'~3 was oil-continuous ~W/O) or water-continuou~ ~O/W~ by ~eeing if a sample of the emulsion dispersed easily in xylene or in water, Thereafter, it was placed under active storage for another 24 hourg. The objective of the active storage test was to characterize the ability of the emulsifier to maintain the emul~ion's integrity. Thig te~t is made to qualitatively simulate the dynamic phenomenon of droplet collison when the O/W emulsion is flowing through a pipeline. About 200 grams of the formulated mixture was placed in a ghak0r bath at 80F.
The shaker bath has a linear travel of l-inch and was operated at 150 cycles/minute, After about 24 hours, the amount of water retained in the emulsion is determined by a 3imple mea~urement of the clear water volume. The higher the water content of the emul~ion after the te~t, the more ~table the emulsion.
Once again, the re~ulting emul~ion was tested as before, to determine whether it was oil-continuous or water-continuous. The re~ults of these p~eliminary tests are shown in Table III.
The following observation~ may be made from the data in Table III~
Water continuous O/W emulsions could not be made with thi~ particular W/O emul~ion cample under the particular experimental test condition~ using 1000 ppm of the emulsifier. No attempt, however, was made to determine the minimum emulsifier dosage required to formulate stable O/W emulsions under the particular te~t conditions.
Both NP-40 and a l-to-l mixture of NP-40 and NP-100 when u~ed~in concentrations greater than or equal to 3000 ppm, under~the particular experimental conditions, produced O/W emulsions with ~ufficient integrity to withstand the active ~torage te~t for 24 hourY.
The presence of the Tretolite demulsifier did not appe~r to aefec~ ~be proae~n, ~` ' .;
~, 8~5~3 1 ~ABLE III
More Data on the Single Step Inversion of Jibaro W/O Emulsions Containinq 50~ Water -- _ _ Nature of Formulated Emulsion hfter After Active Emulsification Emulsifier DenLlsifier(A) Quiescent storage(BJ Water lemp. Conc. Cbnc. Storage for for Rnother Content SF) (pPm)* _(Ppm~* 24 Hrs. 24 Hrs. _ Emulsifier: NP'40 14~ 1000 0 W/O W/O 35 1~9 1000 0 W/O W/O 19 140 1000 200 W/O ~/O 35 165 3000~ 1~0 O/W O~ 32 165~ ~ 3000 1~ O~W O/W 35 140 ~ 500~ ~ 0 O/W O/W 39 189~ ~ ~ 5000 0 ~ O/W O/W 39 ~140 ~ 500~ ~ 2~0 ~ O/W O/W 37 ~189 ~ 50~0~ ~; 200 O/W otw 32 Emulsifier: NP-40/NP-100 - `140~ 1000; ~; ~ 0 ~ W/O W/O 19 ~189~ ~ 1000 ~ ~ ~ W/O W/O 15 ~140 1000~ ; 200 W/O W/O ~ 22 ; 5 ~ ~ IB9~ 1000 200 W/~ W/O 13 -165 ~ 3000~ 100 ~ O/~ O/W 39 165 ~ 3000~ 100 O~ ofw 37 140~ ; 5000 O O~W O/W 42 ;189~ 5~00 ~ O~W O/W 39 ~3 ~ l40~ 500~ 200 O/W O/W 37 189~ 5aoo : ~ ~oo~ o/w o/w 32 *Basèd-on~the~weight~of~the~W/O emulsion A)~ Tretolite Pr~uct. ~
(B)~Put in~Active Storage~a~ter being stor~d under quiescent conditions for ~ 30~ 24~hrs~
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~287~
~BLE III (Cont'd) More Data on the ~ingle Step Inversion of Jibaro W Emulsions Containing 50% Water Nature of Fonmulated Emulsion After A~ter Active Emulsification Emulsifier Demulsifier(A) Quiescent Storage(B) Water Te~p. obnc. Conc. 5torage.for for Another Content 1 ~F) ~ {Pe~)* _ ~ppm)~ 24 Hrs. 24 Hrs. (%) _ EmulsiPier: NP-100 ~ :
140 ~ 1000 ~ o w/o w/o 37 1~9 1~)00 O W/O W/O 13 140 ~ 1000: : ~200 w/o w/o 29 189: ~ ~1000 ~ 200 ~J/O w/o 15 ~ ~ 165 ~ 3000 ~ 10~ w/O w/o 19 165 ~ ; 3000 - ~ ~:100 w/o w/o 15 140~ sooO ~ 0 ; o/w w/o 38 ~189 ~ 5000 ~ o : o/w ~/o 21 40~ sooO ~ ; 20u ~ o~ ~ w/o 32 ;~ 20 ~189 ~ 5000 ~ :200 o/w w/o 19 ~nulsif ier. Np-s~4o:
140; ~ ~ ~ 1000~ 0;~ : ; w/o w/o 26 189~ 1000~ : U; : ~jo : wjo 6 140 ~ 1000~ :20;0 ~ ~ W/O ~ W/O ~ 7 5~ 189~ 10~00~ :200:~ : W/O~ W/O ~ 6 165:~: ~:::::~3000.~ 100 ~ ~ O/W W/O : 6 .~.
165~ 3000 ~ 100 ~ O/W W/O 3 140~ ; 5000~ O/W W/O 13 :189~ 50~0 ~: ~ O O/W W/O 8 ` 30 ~ ;140`~ 5000 : :~ 200 OfW W/O 7 189:~ 5000 _ _~: :200 ~ O/W W/O 13 :
Based~on.~the weight~:of the W/O:emulsion (A)~ ~ tolite~Product.
B)~P t in ~ctive~Storag~ aiter being stored under quiescent conditions ~or 3LZ8~S4~
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Other studie~ have established that the phase inversion temperature, or the temperature above which a water continuou~ emul~ion cannot be formed, i~ a mea~ure of effectivene~s or oil insolubility of the emulsiier. In general, it i~ de~ired that the sy~tem have a phase inver~ion temperature of at lea~t about 185F.
.
It has al~o been ob~erved that the temperature of preparation of the emul~ion will affect phase inversion temperature, the latter increasing with an increase in the temperature Oe emul ion preparation.
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. EMULSION INTO AN OIL-IN-W~TER EHULSION
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Produced crude oil:~in~he field can have substantial quantlties~of~:water associated witb it. The water-cut or 20~ amount~of~water~associated with the oil can be as high as~ 95~:of the~ total~produced~ stream. This is especiall~ ~
true:~in heavy~oil~fiel:ds~where the;oil is being produced ~ -from reservoir~s):~ha~ing a~trong water drive. Usually, the:he:avy oil:~its~elf~ s so:vlscous at ambient tempera-25 :~tures~that it ~requlres:tremendous~pumpi~ng ener~y to wake it flow, if~ at all. ~me:water present ~n the produced stre;am:~c~a:n~be cl:assified:~into two categories: "bound"
water~and~-:fr;ee~ water~ ound"~water is~that water .
wh~ch~is~locked~up:~in~the oil as a water-in-oiI (W/O) emuls~ion.~ Separati`n~ this~water from the stream typi-cally~requires~:applying the appropriate combination of ;heat~ m~ix~in~and~a ch~emicàl demulsifier. "Free" water s~that~wate~r~:~which i~s rèlatively loosely held u~ by the ::oi:l~and~c~an be:~r~emoved: just by heatin~ the stream to the rlght~temp:erature. ~
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~2~37S~3 1 The above-mentioned produced water~in-oil ~W/O) emulsions usually have a higher viscosity than the dry oil which itself is very viscous. This high viscosity frequently limits the rate at which the W/O emulsion, and S hence the oil contained in it, can be pumped up a well-bore or through a pipeline. One method for handling this problem has been to formulate an oil-in~water (O/W) emulsion of the oil. Oil-in-water ~mulsions usually have a lower viscosity than the oil itself and ~o the oil in this form can be pumped at faster rates. Crude oil-in-water emuls$ons have been formulated in one of two ways:
One ap~roach has been to take the produced stream from the wellbore and separate out the water by subject-ing it to a combination of heat, mixing and at least one chemical demulsifier in a heater-treater. The ~dry" oil stream which may contain anywhere from 1-52 water by weight is then ~ixed with the right Emount of water and a chemical emulsifyin~agent to form a low viscosity, trans-portable oil-in-water~emulsion. me amount of water used is governed~by~the need~to obtain a low viscosity trans-port fluid and to~maximize the oil throughput. Normally, a transport O/W emulsion contains from about 15% to about 35~ water by weight.;
The other approach has been to attempt to fnrm an oil-in-water~emulsion within the well~ore itself. Water ~containing one or more emulsifying agentts) is usually ~added~either~down the annulus or the tubin~ to contact the~o~il and~water com~ing from the formation into the well-bore~before or as they enter the downhole pump. In this ~30~ way~ an~ O/W~emulsion of the crude is formed as the fluids pass~;thro~ugh~the downhole~pump. This downhole attempt at ~forminq~O/W~emul~sions presents considerable operational diffi~culties.~ Each well behaves independently of any ` ~ other~well.~; mere~are presented, therefore, a number ;35 of operational variables from well to well which must be ' , .,~
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75'~3 1 constantly combatted if a sultable O/W emulsion is to be formed. More serious is that, in order to produce the oil to ehe surface, it is necessary to use some artificial liftin~ device, and where water content is hi~h, energy requirements for the lifting devices are also high. m is will affect the chemical dosage used. For example, in the case of heavy oil wells with high water cuts wherein enormous amounts of total fluid (oil plus water) have to be lifted to get reasonable oil production rates, it is becoming common to use electrical 6ubmersible pumps (ESP) which can pump out these fluids at tremendous rates. The or~mation of an O/W emulsion is determined by the tempera-t~re, chemical emulsifier dosage and degree of shear or mixing. In a well using an ESP which generates a lot of shear~, an;excessive amount o~ chemical may be required to successfully formulate, if at all, an O/W emulsion.
~According to this invention, there is provided a method for fo m ulating a pipeline-transportable crude oil-in-water (o/W) emulsion by taking the output of one ~or~more crude oil~field~ well(s) and directl~ inverting the produced stream of a water~in-oil~(W/O) emulsion and "free" water, if any. The~formulated O/W emulsion con-~ tains~from~about lS%~to 35%~ by weight of water and hasthe~necessary low viscosity and stability to withstand ~long pipelining~periods~ and any pipeline shut-downs and Btart-ups:. ~ me~ ~o/w emulsion can easily be dewatered and ~de~sal~ted to the~necessa~ry marketing specifications at the ; ~30~ downst~rèam énd~of the pipeline, usin~ known technnology.
The met~hod involvcs usin~ one or more surface-active ` ` ~age~nt(s) and agitation at temperatures ranging from about 100~DF~to~about~200F to invert the produced W/O emulsion and~'lfree" water~in one process step to for~ the O/W
~emulsion. ~The~ purpose is to coalesce all the water :
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~ 87S~3 agent(s) and agitation at temperatures ranging from about 100F to about 200F to invert the produced W/O emulsion and "free" water in one process step to form the O/W
emulsion. The purpo~e ix to coalesce all the water contained in the produced stream of the W/0 emulsion and the "free" water into one continuous phase and simulta-neously disperse the oil in the form of small droplets in this continuous water phase.
There may be employed a ~ingle ~urface-active agent (emulsifier) if it is capable of forming and then sustaining the emulsion over a broad temperature range. A
mixture of surface-active agents may be desirably (emulsifier) employed. Depending on emulsifier, concen-tration may range from about 100 to about 5,000 ppm by weight, of the crude. Where the as-produced W/O emulsion is of high water-content, e.g., about 50% or more water, the amount of emulsifier employed is just sufficient to stabilize an O/W emulsion at a 15% to 35% water-content.
That water which is unnecessary to sustain the O/W
emulsion is allowed to separate from the O/W emulsion prior to introduction of the O/W emul~ion, at the desired water content, into a pipeline. Conversely, when the crude contains les3 water than i required to form a low-viscosity transportable O/W emulsion, water can be added to the W/O emulsion prior to or during transformation into the O/W emul~ion suitable for pipeline transportation.
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12~ 3 The invention is illustrated, by way of example, in the drawings, in which:
Figure 1 illustrates the presently preferred system for practice of the invention;
Figure 2 illustrates in block diagraml the two sequences for forming O/W emulsions in accordance with the invention.
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1;2~37543 The invention is directed towards formulati~g pipeline-transportable oil-in-water (~/W) emulsions by directly inverting a produced stream of a water-in-oil (W/0) emulsion with or without ~free" water, with the aid of an emulsifier ~surface-active chemical), nonmally a mixture of emulsifiers. Furthermore, the invention is also directed towards controllin~ the characteristics of the 0/W emulsion such that it is suitable for pipelining over long distances, e.g., the viscosity, water-content and stability of the emulsion. m e formulated 0/W
emulsion should be easily dewatered and d~esalted ~o the necessary marketing s~ecifications at the downstream end of the pipeline, using known technoloqy.
With reference to lIGS. 1 and 2, (the invention can be generalized~by considering a set of production wells in a heavy~oil field~where~the oil is~being produced from a ~ reservo~r~having a~strong water-drive. Consider that the water-cuts are high and that the welIs have the appropri-ate~artificlal lift syst~ems, e.~., electrical submersible pumps.~ me production streams~from the individual wells are taken~to~a central~point above the ground, where they are commingled.~ However`,~it should~be~ noted that the method~of~for~ulating~ the 0/W emulsion in accordance with the;inven~tîon~can be~carried out at an individual well-head~ At;~this c~entral locatio~n, the co~mingled production ~stream~will~usua~lly cons~îst of the following components:
à~W/~O~emul`sion~ n~free" water, and some associated gas ~îf 0~ anY)~ For~illustrative; purposes,~ we~will assume that ~these~wélls~have~low-producing qas-oil ratîos.
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The~water~present~in the produced stream can be c~lass~iied~ into~two~categories: "bound" water and "free"
~water. nBound~" water is that water which is locked up as a~W/0 emul~sion~ Separating this water from the strea~
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~287S9~3 1~10 _7_ 1 t~pically requires applying the appropriate combination of heat, mixing and chemical additive(s). ~Frse" water is that water which is relatively loosely held up by the oil and can be removed just by heating the stream to the right tem~erature. The amount of "free" water which can be removed will de~end upon the temperature to which the stream is heatedO
This mixture of produced W/o emulsion, "free" water and associsted gas, if any, is fed into a heated vessel, where a certain portion of the ~free" water may be dropped out, with separation of most, ~f not all, of the associated gas. me effluent from this vessel i5 then mixed with an appropriate concentration of an emulsifier, and is fed into an emulsification unit. Alternatively, depending upon the equipment available at the site, the stream may be fed directly to the emulsification unit without any "free" water separation.
e emulsification unit is e~uipped with a heatin~
; unit and a mixer. In the emulsification unit, the idea is to use thP emulsifier at the appropriate temperature, shear to coalesce substantially all the water (~boundn and "freen) present in the incomin~ stream into one con-tinuous phase, and simultaneously disperse the oil phase in the form of small dropIets in this newly-formed con-25 ~ tinuous water phase. The objective is to essentiallyinvert the stream of the W/0 emulsion and "free" water ~into~a~water-external 0/W emulsion. me degree of inver-sion sough;t is~close to~ 100~. The produced W/0 emulsion and~"free'i water mixture is essentially transformed into ~an O~W~;emulsion~in one step. The concentration and the nature~of the~emulsifier are chosen for the ability to achieve the~required deqree of inversion and also bind ; up and stabiIize only that amount of water in the newly-3~ ~
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~L2~7S ~3 16B10 _~_ 1 formed O/W emulsion as is necessary to obtain a low enough viscosity from a pipelining standpoint. Any extra water will be loosely bound and should separate out easily in a quiescent storage vessel.
The O~W emulsion containing excess water (over what is required from a pipelinin~ standpoint) is then fed into a large ~torage vessel, where i~ has enough xesidence time in a quiescent environment, so that the excess water that was not bound up by the emulsifier drops to the bottom of the vessel and can be drained out. In addition to con-taining the pro~er amount of water, the O/W emulsion should contain ~ust enough emulsiier to maintain its stability over long pipelining periods and withstand any pipeline shutdowns and startups. Finally, the emulsion is one that can be easily dewatered and desalted to the necessary marketing specifications at the downstream end of the pi~eline, using known methods and technology.
With specific reference to FIG. l, there is shown a schematic of a typical~facility for applying the invention in the field. The solid lines show equipment essential to the practice of the invention, and dashed lines indicate optional;equipment. Production from a series of producing wells is introduced via flowlines 10, 12 and 14 to a com-mon manifold 16. The commin~led production cominq into the common manifold will be a mixture of a W/~ emulsion, "free" wa;ter and some associated gas, if any. me produc-tion; from ~any well can be fed by manipulation of ~ate valves l8~and 20,~either;to the test facility for gau~ing ~the~oi~l~production rate and the water-content of the strea~, or directly throu~h line 24 to the "free" water knock-out unit ~FWKO) 26, which is an optional piece of ~equi;pment. ~
~ The~FWKO is operated under pressure and has a heat-ing unit~30 in it which allows the process strea~ to be heated to any pre-set temperature within the unit desi~n :
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~Z87S~3 l6sln _9 -1 constraints. This temperature is s0t at the level needed to formulate the O/W emulsion. In the FWK~ unit, depend-in~ upon the tem~erature, a portion, if not all, of the "free" water will drop out of the stream and can be drained off from the bottom throu~h line 32 to the water supply tank 34, which is also optional. The water from this tank can be used, if necessary, employin~ control system 36 to increase the water-content of the FWKO
effluent. Most of the co~produced gas should ~eparate out in the FWKO and is vented through valve 28 to the flare. The FWRO effluent is essentially a mixture of a W/O emulsion and residual "free" water, if any.
If the initial system for separatin~ out the "free"
water and/or heating the stream is not employed, all the equivalent steps may be employed in emulsification unit 51. IndeDendent of whether or not an optional system for water separation and/or heating of the stream for proper for~ation of an O/W emulsion is employed, the feed metered `by meter 3R with a~ cut ~onitor and a sampler, is combined with th~ ~roper~amount of the emulsifier from stora~e uni~t 40. The emulaifying a~ent is pumped out of the tank throu~h line 46~via a flow rate meter 44 and is combined with~the a.s-produced or preprocessed stream. The mix is passed~;through an in-line mixer 50 to the e~ulsification unit 51.~ The~emulsification a~nit has a heating unit;S4 and~an ag~itator 52, wh~ich is a back-up to the in-line mixer~and is optional.~ The objective in this unit is to coalesce~all the~water present in the feed stream as a W/O
~ ~emulsion and~as~"free~" water into one oontinuous phase and ~simùltaneously disperse all the oil in the form of small ~droplets in this con~inuous water Dhase. The idea is to ~invert~the~water-in-oil emulsion and "free" water into an oil-~in-water~emi~lsion in one ste~. The de~ree of inver-~ ~ sion souqht is 100~. me emulsion is formed at a tempera-35~ ture of~from~ahout 100 to about 20nF, preferably from ::
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12~37Si'~3 16~10 -10-1 about 130 to about 17UF. The amount of emulsifier used may ran~e from about 100 to about 5,000 ppm weight-to-weight o~ the hydrocarbon crude, typically from about 500 to about 2,50~ ppm by weight, desirably from about 700 to about 1,0~0 ppm by weight-to-weight.
The actual water-content of the W/O emulsion initially processed at this ~age may vary widely: It may contain up to 95% by volume water, or it may be a relatively dry oil containing less than the amount of water reguired to form a low-viscosity O/W emulsion tha~ is pipeline-pumpable. The object is to provide an O/W emulsion containing from about }5% to a~out 35~ by weight waterr preferably ~rom about 20%
to about 30% by weight water. To this end, tank 34 is used to proYide water externally derived and stored or recovered lS from the as-received wellhead production stream by separa-tion~in unit~26~to ad]ust~the water-content of the O/W
emulsion for it to have an optimum viscosity for pipeline ; pumping. Consequently, the omount of emulsifier added ~` from unit 40 is~oontrolled so as to form a stable O/W
~ emulsion of~a water concentration suited far low-viscosity pipeline pumping~ Any extra water will be loosely bound and~should separate easl~ly~on~keeping the stream quiescent.
~Excess emulsifier is,~therefore, to be avoided in order to prevent the~binding up and inclusion o~ too much water ~;in the~0/W;~emulslon and~lncrease thereby, despite low viscosity, energy requirements for transportation, or to preclude the introduction of too little emulsifier su~ch;~that,;~al~though there~is formed an initial complete O/W~;emulsion,~the amount of emulsifier present is too 30~ ;little~to~s~usta~in~the emulsion at an ambient-temperature v~iscosity level suitable~for pipeline transportation.
The effl~uent of;~the emulsification unit should essen~t~ially be~a~wate~r-external, O/~7 emulsion~ However, ~ ~this~O/W~emulsion may contain quite a bit of extra water ~rel~atlve~to~that required to achieve a certain pipeline :
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~Z~S~3 I viscosity. This effluent goes through a sampler 56 whereby the guality of the inversion achieved, can bs checked. If needed, it can be recycled through line 5~
and tank 53 back to the emulsification unit 51 to ensure formation of a proper o/w emulsion. me pro~erly formed o/W emulsion goes through a degassing boot 64 into ~he shipping tank 72. In the ~hipping tank the objective is to have enough residence time in a quiescent enough environment such that all of the extra water will settle down to the bottom of the tank so that the effluent 0/W
emulsion will contain the right amount of water necessary f~om a pipeline-viscosity standpoint. me extra water sett}ing to the bottom of t~nk 72 can be drained off to the sump. me quality of the oil-in-water e~ulsion is checked~by another meter with a cut monitor and sampler ?0 and, if satisfactory, it is sent to pipeline 80 for transportation to the desired destination.
If the effluent 0/W emulsion from the tank 72 is not suitable for pipel~ining, it can be recycled through line 76 and tank 82, back into shippin~ tank 72 or, if neces-sary, through line 66 back to the emulsification unit.
At this point, it should be noted that as long as thc amount of water in the effluent 0/W emulsion is ~reater than~what is needed, there should be no problem from a 25 ~ pipeline-viscosity standpoint. However, the excess can-not be too large because there may be limitations in the pi~eline~from a pumping-capacity standpoint. There will definitely be a problem if the amount of water in the ~;e~ffluent 0/W emulsion~is less than what is required from - 30 an~effective~pipeline-viscosity standpoint.
As indicated, in the practice of the invention the objective is to~take a produced stream of a mixture of water-in-oil emulsion and "free" water; optionally drop out a~portion o~ the "~free" water, if necessary, or add 3~ some water as the case may be; mix the remaining stream :
~2~7~3 with the appropriate concentration of an emulsifying agent ~mixture of surface-active chemicals); and then invert the same into an oil-in-water emulsion in one step. The idea is to coale~ce all the water present in the feed stream a~
a W/0 emulsion and as "free" water into one continuous phase, and simultaneously disperse all the oil in the foxm of small droplets in the newly-formed continuous water phase. The concentration of the emul ifier used is tailored such that during the procesR of inversion the amount of water which is bound up strongly in the oil-in--water emul~ion will be very clo~e to what is required from a viscosity standpoint. Any extra water, as opposed to "free" water, which i~ loo~ely held up in the oil-in-water emulsion is then removed by pas~ing it through a quie~cent storage unit and the effluent stream iR transportéd through the pipeline.
All supplying systems used to form the 0/W emul~ions are catered to the effluent of the wells. Generally, unless a broad-based emulsifying agent is used, a mixture of at least two emul~ifying agents is employed. Surface -active agents used to form 0/W emulsions may be anionic, `~ cationic, nonionic, amphoteric, and the like. A desired and preferred characteristic is a high degree of oil insolubility. Preferably, the surface active agents are substantially insoluble in oil. Mo~t of the inexpensive and efficient candidate~ for forming crude 0/W emulsion are either anionic or nonionic. Nonionic~ are presently preferred because they are generally cheaper and not ~affected by the salinity of the water.
The be t known of all the anionic-active emulsifying agents~are the soap~ which are the salts of the long chain fatty acids,~derived from naturally occurring fats and oils, in which the acids are found as triglycerides. The soaps used as emul~ifying agents may be obtained from natural oil~, in which ca~e they will consist of a mixture : :
, .. ,~ ' ' . .
.
', , , - ' . .
-~
121~7~3 1 of fatty acids, the precise nature of the mixture depend-ing on the fat or oil employed. The mixed fatty acids o~
tallow, coconut oil, palm oil, and the like, are those commonly employed. The acids derived fro~ tallow, for instance, may be partially separated by filtration or by pressing into "red oil" tprincipally oleic acid) and the the so-called 'Istearic acid" of commerce, which is sold as single-, double-, or triple-pressed, depending on the exten~ to which oleic acid is separated. Such stearic acid is actually a mixture of stearic and palmitic acids.
The nonionic surface-active agents can be classified into five~types, namely, ether linkage, ester linkage, amide linkage, miscellaneous linkages, and multiple linkage. ~he preferred nonionic emulsifiers are selected ~from the compoùnds having the general formula:
`
, R ~ O - tCH2CH2O)nH
and ~ R
x ~ o - ~ CH2CH20 ) nH
~ where~R~Is~any hydrocarbon group and n is the number of~
25 ~ ~poIyGxethyIene~groups ranging`~rom about 4 to about 100, ;preferab~ly about 30 to about'7100, and substantially oil ~insoluble.
The most prominent members o this class are those campounds~ formed by the reaction of a hydrophobic ~30~ hydroxyI-sonta~Inlng compound, e.g., an alcohol or phenol, with~et~hylene oxide, or, to a lesser extent, propylene oxlde.~ ~The ethyle~ne oxide groups, for example, may be added~to a~ny~d;esi~red extent.~
Nonlonic~surface-active agents hav~ins an ester link-35 ~ ~age~include~compounds of the following general formula:
.
.
.
:. " , `: :
. ~
~Z8~S~3 R - C - 0 - (CH2CH20~nH
where R and n are as defined above.
The esters formed by the reaction of the fatty acid with polyhydric alcohols are a particularly interesting group of nonionic emulsifiers, in that, depending on the nature of the alcohol used, they may be predominantly hydrophilic and are especially suitable as 0/W emulsiiers.
An example of an ester-linkage surfactant which is a good emulsifier i5:
; C17H35 - C - 0 - (CH2cH20)5oH
;~ The presently.preferred ester linkage surfactants are of the formula~
CgHlg ~ 0 - (CH2CH2oj~
;wherein~y~is from~abou~t~9 to about 100 wlth at least a :: . :port:ion of:the agent;:being compounds wherein y is at : l~east~about~40 to ensure a~subs:tantial:degree of oil insolubllity.~
~Z5~ Nonionic emulsifiers with~amide linkages are com-pounds of~:the~ge~ner~al formula:
(CH2CH20)nH
~ \ (CH2CH20)nH
~ wher~e~R and~n are~as defined~above.
u~ Th~e~emul~s1fier~system~used in the practice of the invention~;must enable:formation of the Q/W emulsion at 35~ e~1evat:ed temperatures~and retention of stability at JL;Z ~7S ~;~
1681~ -15-1 smbient temperatures. Unless broad-based ~or ~uch func-tionality, a mixture o~ two or more emulsifiers is employed, and is particularly preferred.
There are several advantages for applying the inven-tion for formulating oil-in-water emulsions in the field:
a) It would be particularly useful in the initial stages of developing a new field or in a ~ield where there are only about one or two wells and it is not economical to construct a large production ~acility. In such instances, the invention reduces the number and the size of the mechanical facilities to be installed. This is because inverting in one stage the mixture of the pro-duced W~O emulsion and the ~frée" water, if any, elimi-nates the need to have one unit for demulsification and one unit for emulsification. As mentioned earlier, the process may;be op~imized by separating, i~ necessary, some~ of the "free" water out of the produced stream :
before making the emuIsion; however, this is not essen-~tial.;~Por e~x~ample, in a~new flçld where there is no ~roduction facility, the total stream of the produced W/0 emuls~lon~and;all~the "~ree' water can be inverted into an O/W em~ulsion in~one stage. There would be~employed an ~ppropriate concentration of the right emulsifier mixture to bind~up only that porti~on of the water required for obtaining the~effective;viscosity needed for pipelining.
Broad~ly speak~ing, applying the invention would really ~involve h~a~vlng a mixing device, an emulsification unit, and~a~aettllng ta~nk~for~dropping off the excess water.
th~is new~field is~close to an existing field with a 30~; 1a~rge~production~faci}ity, the 0/W emulsion containing excess~-water can be injected directly into a short pipe-~line~to~this~;neighboring facility. In this event, the settling tank can be eliminated.
In~summary~,~ o~rmulatlng an 0/W emulsion by this 3S ~method~can~potentially decrease the capital cost o~ a :
: ~ : :
, .
:` : : :
~2~ 3 1 production facility to be installed in a new heavy-oil field. Furthermore, since the produced stream is not demulsified first, it can also potentially reduce the chemical cost.
b) If the wells have high water-cuts, there will be a lot of co-produced water. Using the co-produced - water to form the emulsion will alleviate the water-disposal problem.
c) It has been observed during pipelining of an O/W emulsion formulated by mixing water and an emulsifying agent with a dried oil stream, that some of the water is transferred from the external, continuous phase into the oil drop}ets. This can, depending upon the extent of the water lost to the oil, increase the effective viscosity of the O/W emulsion, which can lead to problcms if it is necessary to stop and restart the pipeline. The amount of water lost to~the oil during the transport o~ the O/W
emulsion~is less if the oil is not treated and dried ~ bef~ore it is emulsified. Hence, formulating an O/W
emulsion by invert1ng~the produced W/O emulsion in one step, as outlined in the; invention, would be better for long-dlstance pipeline~applications.
~ Without limiting,~the following Examples illustrate, the 1nstant Invention in part.
:: : : : : :
Example 1 The~o11 samples used for these investigations were rom~;the~Jibaro Fi~eld in the Peru Oriente, and were pro-; v1ded;~i~n 5-gallon~containers. Karl Fisher water analyses 30~ ;were~performed, revea1ing that the four samples each con-~tai;ne~d~514, plus or minus 2%, total water. The samples we~re~heated to~65C ~149F) for 4 hours, and any "free"
water~that~separated out, was removed. Only 2% of the ~water~in~ the~sampIes dropped out on heating to this ~temperatu~re. The~warm W/O emulsion was then mixed with . :; ~ :
.
, , :, :
128~S'~3 the appropriate amount of emulsifier in a mixer. Mixin~
energies and times were kept to a minimum. The O/U emul-sions formed were then allowed to stand for 30 minutes and viscosities were measured. ~mulsifier was added, either directly to the W/O emulsion or dissolved in 5 weight-percent produced water which had been separately made available. The emulsifying agent was a mixture of two surface-active chemicals, manufactured and sold by Tetrolite, of St. Louis, MO, a division of Petrolite Corporation. The reversal of emulsion phases was found ~o be more delicate than emulsifying relatively dry oil into water. Adding demulsifier to the W/O emulsion such that some water was dropped out before Adding the emulsi-fier, did not appear to be as effective as operating on the provided W/O emulsion, in that the system was very limited in allowable temperatures, mixing times and treating rates.
The results of forming O/W emulsions by directly inverting the produced ~l/O emulsions at an emulsifier concentration~of~2,000ppm, based on the weight of the treated W/O emulsion, are~shown in Tables I and II.
Table I
~ 70F Viscosity vs._Shear Rate : : ;
;~ As-Formed Shear Rate sec.~l Viscosity, cp 200 ~ 22 600 ~ 18 1 0 0 0 :~
::: ~: :
, ~
~2~7S~3 ' Table II
70~ Viscosity vs. Shear Rate Upper Phase after Water Separation Shear Rate sec.-l Viscosity, cp .
10 400 1~0 Stability~of the O/U emulsions was measured by allow-ing the emulsions to s~and quiescent~ overnight. About 24 by~volume extra water dropped out. This indicates that the~upper emulsifled pbase contained about 33~ water by volume.~ Based on this information, it is believed fea-sible to invert, in one step, a ~/O emulsion containin~
~50% or more~water using from 1000 to 2000 ppm o~ the emul-~si~fl~er,~based~on the weight of the tre;ted~/O emulsion.
~The;stability of~these~emulsions is such that, from 25%~
to 35%~wa~ter~is indefinitely stable. ~ased on viscosity ~;datà,~ it~ s~es;timated~that the upper-phase emulsion, wh~ch contains a nominal 33~ water, actually contains from about -~28%~to~30%~wat~er as a~continuous phase and from 3% to 5%
wate~ as~dlspersed~droplets.
~30 ~ Example 2 Add1ti~onal~studles were~ performed using another batch o~producéd Jibaro~W/O;~emul ion containing 50% water. The sa~pl~e~bad~been~in storage for several months after being collected~ n the;fle~ld~and was old. No water had dropped :
: :
. ~ :
, ~ , ~8~S~3 out of the sample even though it had been stored for several months. This indicate~ that the sample was unduly refractory and les3 representative of fresh oil-field W~0 emulsions.
The emulsifiers u~ed in the testing series were the ethoxylated nonylphenols. They are all members of the general family of nonionic ~urface active agents of the formula:
C9Hl9 ~ 0 - (CH2CH20)yH
The ethoxylated nonylphenols ~NP series) are characterized by y = 4-100.
The following member~ of the NP family were tested:
NP No. y The required emulsifier concentration was found to depend strongly on the age of the produced W/0 emulsion, the emulsification temperature and the mixing efficiency.
In using an old W/0 emul ion sample, only qualitative trends can be drawn about the behaviour of the system3 te~ted.
All the te ts were conducted by shearing the mixture of the W/0 emulslon and the added emulsifier using a rotor- tator mixing device. In some ca~es, a small dose of a demuls~ifying agent,~also produced by Tretolite, was added along with the emulsifier. The rotor-stator gap and the speed were adju~ted to generate about 10-4 sec-l of ~` 30 ~hear. Each mixture was ~heared at this ~ame rate for about~40 seconds. No attempt was made to vary the manner ln~whlch the~shear was~applied. After shearing, the resulting mixture was stored under quiescent condition~
~for~about 24 hours. It was then evaluated to determine 3S whether it ,~ ' , :
:
~LZi~7S'~3 was oil-continuous ~W/O) or water-continuou~ ~O/W~ by ~eeing if a sample of the emulsion dispersed easily in xylene or in water, Thereafter, it was placed under active storage for another 24 hourg. The objective of the active storage test was to characterize the ability of the emulsifier to maintain the emul~ion's integrity. Thig te~t is made to qualitatively simulate the dynamic phenomenon of droplet collison when the O/W emulsion is flowing through a pipeline. About 200 grams of the formulated mixture was placed in a ghak0r bath at 80F.
The shaker bath has a linear travel of l-inch and was operated at 150 cycles/minute, After about 24 hours, the amount of water retained in the emulsion is determined by a 3imple mea~urement of the clear water volume. The higher the water content of the emul~ion after the te~t, the more ~table the emulsion.
Once again, the re~ulting emul~ion was tested as before, to determine whether it was oil-continuous or water-continuous. The re~ults of these p~eliminary tests are shown in Table III.
The following observation~ may be made from the data in Table III~
Water continuous O/W emulsions could not be made with thi~ particular W/O emul~ion cample under the particular experimental test condition~ using 1000 ppm of the emulsifier. No attempt, however, was made to determine the minimum emulsifier dosage required to formulate stable O/W emulsions under the particular te~t conditions.
Both NP-40 and a l-to-l mixture of NP-40 and NP-100 when u~ed~in concentrations greater than or equal to 3000 ppm, under~the particular experimental conditions, produced O/W emulsions with ~ufficient integrity to withstand the active ~torage te~t for 24 hourY.
The presence of the Tretolite demulsifier did not appe~r to aefec~ ~be proae~n, ~` ' .;
~, 8~5~3 1 ~ABLE III
More Data on the Single Step Inversion of Jibaro W/O Emulsions Containinq 50~ Water -- _ _ Nature of Formulated Emulsion hfter After Active Emulsification Emulsifier DenLlsifier(A) Quiescent storage(BJ Water lemp. Conc. Cbnc. Storage for for Rnother Content SF) (pPm)* _(Ppm~* 24 Hrs. 24 Hrs. _ Emulsifier: NP'40 14~ 1000 0 W/O W/O 35 1~9 1000 0 W/O W/O 19 140 1000 200 W/O ~/O 35 165 3000~ 1~0 O/W O~ 32 165~ ~ 3000 1~ O~W O/W 35 140 ~ 500~ ~ 0 O/W O/W 39 189~ ~ ~ 5000 0 ~ O/W O/W 39 ~140 ~ 500~ ~ 2~0 ~ O/W O/W 37 ~189 ~ 50~0~ ~; 200 O/W otw 32 Emulsifier: NP-40/NP-100 - `140~ 1000; ~; ~ 0 ~ W/O W/O 19 ~189~ ~ 1000 ~ ~ ~ W/O W/O 15 ~140 1000~ ; 200 W/O W/O ~ 22 ; 5 ~ ~ IB9~ 1000 200 W/~ W/O 13 -165 ~ 3000~ 100 ~ O/~ O/W 39 165 ~ 3000~ 100 O~ ofw 37 140~ ; 5000 O O~W O/W 42 ;189~ 5~00 ~ O~W O/W 39 ~3 ~ l40~ 500~ 200 O/W O/W 37 189~ 5aoo : ~ ~oo~ o/w o/w 32 *Basèd-on~the~weight~of~the~W/O emulsion A)~ Tretolite Pr~uct. ~
(B)~Put in~Active Storage~a~ter being stor~d under quiescent conditions for ~ 30~ 24~hrs~
- ;~ ; ' . . :
: .. - . :
-. ' :
~287~
~BLE III (Cont'd) More Data on the ~ingle Step Inversion of Jibaro W Emulsions Containing 50% Water Nature of Fonmulated Emulsion After A~ter Active Emulsification Emulsifier Demulsifier(A) Quiescent Storage(B) Water Te~p. obnc. Conc. 5torage.for for Another Content 1 ~F) ~ {Pe~)* _ ~ppm)~ 24 Hrs. 24 Hrs. (%) _ EmulsiPier: NP-100 ~ :
140 ~ 1000 ~ o w/o w/o 37 1~9 1~)00 O W/O W/O 13 140 ~ 1000: : ~200 w/o w/o 29 189: ~ ~1000 ~ 200 ~J/O w/o 15 ~ ~ 165 ~ 3000 ~ 10~ w/O w/o 19 165 ~ ; 3000 - ~ ~:100 w/o w/o 15 140~ sooO ~ 0 ; o/w w/o 38 ~189 ~ 5000 ~ o : o/w ~/o 21 40~ sooO ~ ; 20u ~ o~ ~ w/o 32 ;~ 20 ~189 ~ 5000 ~ :200 o/w w/o 19 ~nulsif ier. Np-s~4o:
140; ~ ~ ~ 1000~ 0;~ : ; w/o w/o 26 189~ 1000~ : U; : ~jo : wjo 6 140 ~ 1000~ :20;0 ~ ~ W/O ~ W/O ~ 7 5~ 189~ 10~00~ :200:~ : W/O~ W/O ~ 6 165:~: ~:::::~3000.~ 100 ~ ~ O/W W/O : 6 .~.
165~ 3000 ~ 100 ~ O/W W/O 3 140~ ; 5000~ O/W W/O 13 :189~ 50~0 ~: ~ O O/W W/O 8 ` 30 ~ ;140`~ 5000 : :~ 200 OfW W/O 7 189:~ 5000 _ _~: :200 ~ O/W W/O 13 :
Based~on.~the weight~:of the W/O:emulsion (A)~ ~ tolite~Product.
B)~P t in ~ctive~Storag~ aiter being stored under quiescent conditions ~or 3LZ8~S4~
, .
Other studie~ have established that the phase inversion temperature, or the temperature above which a water continuou~ emul~ion cannot be formed, i~ a mea~ure of effectivene~s or oil insolubility of the emulsiier. In general, it i~ de~ired that the sy~tem have a phase inver~ion temperature of at lea~t about 185F.
.
It has al~o been ob~erved that the temperature of preparation of the emul~ion will affect phase inversion temperature, the latter increasing with an increase in the temperature Oe emul ion preparation.
:
:: :
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. - , .
Claims (25)
1. A process for the production of an oil-in-water emulsion for pipeline transmission which comprises:
a) producing a hydrocarbon crude including a water-in-oil emulsion;
b) adding to said hydrocarbon crude when said crude is at a temperature of from about 100° to about 200°F, an emulsifier system which is capable of forming and sustaining an oil-in-water emulsion at said temperature and at ambient pipeline transmission temperatures, the amount of emulsifier system added being sufficient to form and sustain an oil-in-water emulsion having a selected water content of from about 15 percent to about 35 percent by weight water and a viscosity sufficiently low for pipeline transmission;
c) agitating the hydrocarbon crude including a water-in-oil emulsion and the added emulsifier system, to form an oil-in-water emulsion; and d) separating any excess water from the formed oil-in-water emulsion.
a) producing a hydrocarbon crude including a water-in-oil emulsion;
b) adding to said hydrocarbon crude when said crude is at a temperature of from about 100° to about 200°F, an emulsifier system which is capable of forming and sustaining an oil-in-water emulsion at said temperature and at ambient pipeline transmission temperatures, the amount of emulsifier system added being sufficient to form and sustain an oil-in-water emulsion having a selected water content of from about 15 percent to about 35 percent by weight water and a viscosity sufficiently low for pipeline transmission;
c) agitating the hydrocarbon crude including a water-in-oil emulsion and the added emulsifier system, to form an oil-in-water emulsion; and d) separating any excess water from the formed oil-in-water emulsion.
2. A process for the production of an oil-in-water emulsion for pipeline transmission which comprises:
a) producing a hydrocarbon crude including a water-in-oil emulsion and containing in excess of 35 percent by weight water.
b) elevating the temperature of the hydrocarbon crude including a water-in-oil emulsion from about 100°
to about 200°F and adding an emulsifier system capable of forming and then sustaining an oil-in-water emulsion:
at said temperature and at ambient pipeline transmission temperatures, the amount of emulsifier system added being sufficient to form and sustain an oil-in-water emulsion having a selected water content of from about 15 percent to about 35 percent by weight and a viscosity sufficiently low for pipeline transportation;
c) agitating the hydrocarbon crude including a water-in-oil emulsion and the added emulsifier system, to form an oil-in-water emulsion; and d) separating excess water from the formed oil-in-water emulsion.
a) producing a hydrocarbon crude including a water-in-oil emulsion and containing in excess of 35 percent by weight water.
b) elevating the temperature of the hydrocarbon crude including a water-in-oil emulsion from about 100°
to about 200°F and adding an emulsifier system capable of forming and then sustaining an oil-in-water emulsion:
at said temperature and at ambient pipeline transmission temperatures, the amount of emulsifier system added being sufficient to form and sustain an oil-in-water emulsion having a selected water content of from about 15 percent to about 35 percent by weight and a viscosity sufficiently low for pipeline transportation;
c) agitating the hydrocarbon crude including a water-in-oil emulsion and the added emulsifier system, to form an oil-in-water emulsion; and d) separating excess water from the formed oil-in-water emulsion.
3. A process as claimed in claim 1 in which the temperature of the hydrocarbon crude, including a water-in-oil emulsion, is from about 130° to about 170°F during formation of the oil-in-water emulsion.
4. A process as claimed in any one of claims 1 to 3 n which the emulsifier system contains at least one emulsifier capable of sustaining the oil-in-water emulsion at the elevated temperature and at least one emulsifier capable of sustaining the formed oil-in-water emulsion at ambient temperatures of pipeline transmission.
5. A process as claimed in any one of claims 1 to 3 which the emulsifier system is provided in a concentration of from about 100 to about 5000 ppm by weight of the hydrocarbon crude.
6. A process as claimed in any one of claims 1 to 3 in which the emulsifier system is provided in a concentration of from about 500 to about 2500 ppm by weight of the hydrocarbon crude.
7. A process as claimed in any one of claims 1 to 3 in which the hydrocarbon crude, including a water-in-oil emulsion, contains less than 15 percent by weight water, and water is added for formation of the oil-in water emulsion.
8. A process as claimed in any one of claims 1 to 3 in which the hydrocarbon crude contains bound and free water, and at least a portion of the free water is separated from the hydrocarbon crude prior to forming the oil-in-water emulsion.
9. A process as claimed in claim 1 in which the emulsifier system comprises at-least one substantially oil insoluble emulsifier which is a nonyl phenol compound of the formula:
wherein y is from about 9 to about 100.
wherein y is from about 9 to about 100.
10. A process as claimed in claim 9 in which the emulsifier system comprises at least one nonyl phenol compound in which y is from about 40 to about 100.
11. A process as claimed in claim 1 in which the hydrocarbon crude including a water-in-oil emulsion con-tains up to 95 percent by weight water,
12. A process as claimed in claim 1 in which the emulsifier system contains at least one emulsifier capable of sustaining the oil-in-water emulsion at the temperature of formation and at ambient temperatures of pipeline transmission.
13. A process for the production of an oil-in-water emulsion for pipeline transmission which comprises:
a) producing a hydrocarbon crude including a water-in-oil emulsion and containing more than 35 percent by weight water in the form of "bound" and "free" water;
b) separating at least a portion of the "free"
water from the hydrocarbon crude;
c) elevating the temperature of the hydrocarbon crude including a water-in-oil emulsion from about 100°
to about 200°F, and adding an emulsifier system capable of forming then sustaining an oil-in-water emulsion at said temperature and at ambient pipeline transmission temperatures, the amount of emulsifier system added being sufficient to form and sustain an oil-in-water emulsion having a selected water content of from about 15 percent to about 35 percent by weight water and a viscosity sufficiently low for pipeline transportation;
d) agitating the hydrocarbon crude including a water-in-oil emulsion and the added emulsifier system, to form an oil-in-water emulsion; and e) separating any excess water from the formed water-in oil emulsion.
a) producing a hydrocarbon crude including a water-in-oil emulsion and containing more than 35 percent by weight water in the form of "bound" and "free" water;
b) separating at least a portion of the "free"
water from the hydrocarbon crude;
c) elevating the temperature of the hydrocarbon crude including a water-in-oil emulsion from about 100°
to about 200°F, and adding an emulsifier system capable of forming then sustaining an oil-in-water emulsion at said temperature and at ambient pipeline transmission temperatures, the amount of emulsifier system added being sufficient to form and sustain an oil-in-water emulsion having a selected water content of from about 15 percent to about 35 percent by weight water and a viscosity sufficiently low for pipeline transportation;
d) agitating the hydrocarbon crude including a water-in-oil emulsion and the added emulsifier system, to form an oil-in-water emulsion; and e) separating any excess water from the formed water-in oil emulsion.
14. A process as claimed in claim 13 in which the temperature of the crude is from about 130° to about 170°F
during formation of the oil-in-water emulsion.
during formation of the oil-in-water emulsion.
15. A process as claimed in claim 13 in which the emulsifier system contains at least one emulsifier capable of sustain in the oil-in-water emulsion at the temperature of formation and at least one emulsifier capable of sustaining the formed oil-in-water emulsion at ambient temperatures of pipeline transmission.
16. An emulsifier for use in transforming a water-in-oil emulsion into an oil-in-water emulsion which comprises a 1:1 mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
17. An oil-in-water emulsion which contains an emulsifier system to sustain the emulsion at a concentration of at least 3,000 p.p.m. said emulsifier system being of a 1:1 mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
18. An emulsifier comprising a 1:1 mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
19. An emulsifier comprising a mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
20. A composition comprising an oil-in-water emulsion and an emulsifier comprising a mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent, the emulsifier being present in an amount sufficient to stabilize the emulsion at a water concentration suited for low-viscosity pipeline pumping.
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent, the emulsifier being present in an amount sufficient to stabilize the emulsion at a water concentration suited for low-viscosity pipeline pumping.
21. A composition comprising an oil-in-water emulsion and an emulsifier comprising a mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent, the emulsifier being present in an amount sufficient to sustain the emulsion at an ambient-temperature viscosity level suitable for pipeline transportation.
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent, the emulsifier being present in an amount sufficient to sustain the emulsion at an ambient-temperature viscosity level suitable for pipeline transportation.
22. A process for maintaining an oil-in-water emulsion which including in said emulsion and emulsifier system in an amount sufficient to sustain the emulsion, said emulsifier system being of a 1:1 mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
wherein y is 40 for one of the nonionic surface active agents and y is 100 for the other nonionic surface active agent.
23. A process as claimed in claim 22 in which emulsifier concentration is at least 3,000 p.p.m.
24. A process for the production of an oil-in-water emulsion for pipeline transmission which comprises:
(a) producing a hydrocarbon crude including a water-in-oil emulsion;
(b) adding to said hydrocarbon crude when said crude is at a temperature of from about 100° to about 200° F, an emulsifier system comprising a 1:1 mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents, and y is 100 for the other nonionic surface active agent provided in an amount sufficient to form and sustain an oil-in-water emulsion at said temperature and at ambient pipeline transmission temperatures, said formed and sustained oil-in-water emulsion having a viscosity sufficiently low for pipeline transmission;
(c) agitating the hydrocarbon crude including a water-in-oil emulsion and the added emulsifier system to form an oil-in-water emulsion; and (d) separating any excess water from the formed oil-in-water emulsion.
(a) producing a hydrocarbon crude including a water-in-oil emulsion;
(b) adding to said hydrocarbon crude when said crude is at a temperature of from about 100° to about 200° F, an emulsifier system comprising a 1:1 mixture of nonionic surface active agents of the formula:
wherein y is 40 for one of the nonionic surface active agents, and y is 100 for the other nonionic surface active agent provided in an amount sufficient to form and sustain an oil-in-water emulsion at said temperature and at ambient pipeline transmission temperatures, said formed and sustained oil-in-water emulsion having a viscosity sufficiently low for pipeline transmission;
(c) agitating the hydrocarbon crude including a water-in-oil emulsion and the added emulsifier system to form an oil-in-water emulsion; and (d) separating any excess water from the formed oil-in-water emulsion.
25. A process for the production of an oil-in-water emulsion for pipeline transmission which comprises:
(a) producing a hydrocarbon crude including a water-in-oil emulsion and containing in excess of 35 percent by weight water;
(b) elevating the temperature of the hydrocarbon crude including a water-in-oil emulsion to a temperature from about 100° to about 200° F., and adding an emulsifier system comprising a 1:1 mixture of oil insoluble nonyl phenol compound surface active agents of the formula:
wherein y is 40 for one of the surface active agents and y 100 is for the other surface active agent to form and then sustain an oil-in-water emulsion at said temperature and at ambient pipeline transmission temperature, the amount of emulsifier system added being sufficient to form and sustain an oil-in-water emulsion having a selected water content of from about 15 percent to about 35 percent by weight and a viscosity sufficiently low for pipeline transportation;
(c) agitating the hydrocarbon crude, including a water-in-oil emulsion and the added emulsifier system, to form an oil-in-water emulsion; and (d) separating excess water from the formed oil-in-water emulsion.
(a) producing a hydrocarbon crude including a water-in-oil emulsion and containing in excess of 35 percent by weight water;
(b) elevating the temperature of the hydrocarbon crude including a water-in-oil emulsion to a temperature from about 100° to about 200° F., and adding an emulsifier system comprising a 1:1 mixture of oil insoluble nonyl phenol compound surface active agents of the formula:
wherein y is 40 for one of the surface active agents and y 100 is for the other surface active agent to form and then sustain an oil-in-water emulsion at said temperature and at ambient pipeline transmission temperature, the amount of emulsifier system added being sufficient to form and sustain an oil-in-water emulsion having a selected water content of from about 15 percent to about 35 percent by weight and a viscosity sufficiently low for pipeline transportation;
(c) agitating the hydrocarbon crude, including a water-in-oil emulsion and the added emulsifier system, to form an oil-in-water emulsion; and (d) separating excess water from the formed oil-in-water emulsion.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/802,849 US4646771A (en) | 1984-03-02 | 1985-11-27 | One-step system for transforming a water-in-oil emulsion into an oil-in-water emulsion |
| US06/802,851 US4627458A (en) | 1984-03-02 | 1985-11-27 | One-step process for transforming a water-in-oil emulsion into an oil-in-water emulsion |
| US802,849 | 1985-11-27 | ||
| US802,851 | 1985-11-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1287543C true CA1287543C (en) | 1991-08-13 |
Family
ID=27122496
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000517675A Expired - Lifetime CA1287543C (en) | 1985-11-27 | 1986-09-08 | One-step process for transforming a water-in-oil emulsion into an oil-in-water emulsion |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1287543C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113171720A (en) * | 2021-04-28 | 2021-07-27 | 宿迁明江化工股份有限公司 | Feeding device of demulsifier and use method |
-
1986
- 1986-09-08 CA CA000517675A patent/CA1287543C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113171720A (en) * | 2021-04-28 | 2021-07-27 | 宿迁明江化工股份有限公司 | Feeding device of demulsifier and use method |
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