CA2184191A1 - Method and apparatus for breaking hydrocarbon emulsions - Google Patents
Method and apparatus for breaking hydrocarbon emulsionsInfo
- Publication number
- CA2184191A1 CA2184191A1 CA002184191A CA2184191A CA2184191A1 CA 2184191 A1 CA2184191 A1 CA 2184191A1 CA 002184191 A CA002184191 A CA 002184191A CA 2184191 A CA2184191 A CA 2184191A CA 2184191 A1 CA2184191 A1 CA 2184191A1
- Authority
- CA
- Canada
- Prior art keywords
- oil
- water
- emulsion
- zone
- acoustic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G33/00—Dewatering or demulsification of hydrocarbon oils
- C10G33/06—Dewatering or demulsification of hydrocarbon oils with mechanical means, e.g. by filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
- B01D17/02—Separation of non-miscible liquids
- B01D17/0208—Separation of non-miscible liquids by sedimentation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
- B01D17/02—Separation of non-miscible liquids
- B01D17/04—Breaking emulsions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
- B01D17/02—Separation of non-miscible liquids
- B01D17/04—Breaking emulsions
- B01D17/047—Breaking emulsions with separation aids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J19/10—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing sonic or ultrasonic vibrations
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/34—Treatment of water, waste water, or sewage with mechanical oscillations
- C02F1/36—Treatment of water, waste water, or sewage with mechanical oscillations ultrasonic vibrations
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G33/00—Dewatering or demulsification of hydrocarbon oils
- C10G33/04—Dewatering or demulsification of hydrocarbon oils with chemical means
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
A method for breaking an emulsion comprising oil and water into oil and water phases comprising treating the emulsion with a chemical demulsifier and passing the mixture through a hollow chamber (22) having a uniform cross section and subjecting the mixture to acoustic energy in the frequency range of about 1.0 to 10.0 kHz, preferably 1.25 kHz, to enhance breaking the emulsion into a water phase and oil phase. The oil phase is then separated from the water phase by gravity separation and recovered. The sonic energy is generated by a transducer (64) attached to the mid-section of the upper or lower outer surface of the hollow chamber (22). For emulsions containing light oils having an ALI gravity greater than 20 and water, the emulsion can be broken by the use for acoustic energy in the frequency range of about 1.0 to 10.0 kHz without the addition of chemical demulsifiers.
Description
2 ~18 4191 PCTIUS95107604 METHOD AND APPARATUS FOR i3REAKING HYDROCARi30N EMULSIONS
This invention relates to a method and apparatus f or breaking hydrocarbon emulsions, particularly hydrocarbon 1 ci rn~ containing oil and water into separate phases . More 5 particularly, the present invention relates to a method and apparatus for PnhAnrinj the separation of water-in-oil ~ ,nc containing petroleum recovered from und~LyLoulld reservoirs into water and crude oil phases by employing sonic acoustic energy in the fre~uency range of about l. 0 to 10. 0 kHz whether alone 10 or in conjunction with chemical demulsifiers.
In oil fields, water usually is co-produced with crude oil and becomes entrained with the oil to become an l ~io~ . The crude oil must generally be free of water (0.5% or less) before it can be sold and LLalla~uL ~ed in pipelines. The complexity of 15 separating mixtures of water and oil depends upon the physical form of the water. Where the mixture has only "free" water, the water will separate readily from the oil because of the differences in gravities of the water and oil. This type of separation ~Lest:llL5 no problem other than providing a vessel in 20 which water-oil phase separation can occur. However, the water can be dispersed L1ILUU~11UUL the oil in very minute particles, usually with ~; i Prs less than 25 microns. This mixture may be termed an lr~i.,n and is very difficult to separate into water and oil phases.
In these emulsions, the small particles of water are dispersed in the oil in a stable condition for several reasons.
First, the area of the interface between oil and water in a stable emulsion is very substantial. For example, the interfacial area of one gallon (0.005 m3) of water dispersed within oil would range from about 1,000 to 300,000 s~uare feet (93 to 28000 m2). The interfacial area of the water in the oil is stabilized against rOAlPCrPnrP by two factors in a stable emulsion. The minute size of the dispersed water is one factor to provide an ai ,~-re nPcPC:cAry for emulsion stability. The 3~ second factor is the ~L~s~n-~ of emulsifying agents or surfactants which completely coat the interfacial area to form a protective high-viscosity film that :~uLLuul~ds and stabilizes Wo 95/34522 PCTn~Ss5/07604 218~gl , O
the dispersed water within the continuous oil phase- This film prevents the coalescence of the disper5ed water in the emulsion into separate water and oil phases.
The breaking of emulsions in which water is dispersed in 5 the continuous crude oil phase requires performing certain functions. Initially, the interfacial protective film ~uLLuul.ding the dispersed water within the : l cion must be weakened or dl::,LLuyed. Then, the particles of water must rn;l l ~ccP into droplets of water which can undergo settling 10 through the effects of gravity- Thereafter, the rn~ cce~
droplets of water àre separated as a water phase from the oil phase .
Breaking of emulsions may be achieved by physical and ~-h~ c~ l treatments, application of heat, and electrical 15 methods. Generally, the methods for breaking a water-in-oil emulsions usually employ a combination of these treatments. In many instances, rhPmir~l 1 lCi~iers may be employed for assisting in the breaking of the protective film which 2~ULLUUlldS
the dispersed water. The d lc;fiers are added to the: lc~n 20 to counter-act the effects of the emulsifiers which provide the 6tability of the dispersed water particles in the continuous oil phase. The demulsifier is uniformly distributed throughout the lci~-~ so as to be present at all interfaces between the water and oil before the emulsion is processed in a treating facility.
There are a multitude of complex ~!hf-rniCAl Compositions which serve as ~' lcifiers for breaking water-in-oil emulsions.
Surf ace-active materials have been used successfully as ,1 lcifiers. The ~ mlllc;fi~rs usually have a variety of polar ,- -ntS with a ~uLeLeLLad solubility ranging from 30 pre~' ;n~ntly oil-soluble to prP~ln~in~ntly water-soluble An emulsifying agent st~h; l; ~ec an ~ l ci ~ which effect can be counteracted by a demulsif ier .
The selection of a d l c; fier for breaking a particular emulsion may be based upon actual tests and trials performed in 35 the : 1 c; r~ . Several methods are available to screen the ~ lc;flers, Usually the type of the d lCif;.~.-, and its amount in use, are best est~hl;cho~ by e~perimentatiOn directly ~ 4~9~
at the facility used to separate the emulsion into water and oil phases .
Many types of organic and inorganic materials help stabilize emulsionS. Inorganic solids such as 5and, clays, iron 5 sulphide, rust, etc. stabilize water-in-oil - lc;~nc, In addition, organic solids such as asphaltenes and paraffin can also provide 5tability to lcinnc, Chemical6, for example cationic and anionic surfactants, are commonly added to ~Luduced f luids in order to break emulsions in the oil ~ield . Heat and 10 r-~h~n;rll methods are al50 commonly used alone, or in conjunction with chemicals to dest~h; 1 i 7e and break ~ 1 c jx~n~
into oil and water phases. Millions of dollars are 5pent each year in chemical treating and heating costs for control of cm1l1 ci nn~, US-A-3200567 flicrlosPc the use of ultra50nic treatment in the frequency range of 200 kHz to 400 kHz to break oil-water c lci~nc in a continuous flow treatment.
US-A-3594314 rliccl~c~c the use of ultrasonic treatment in the ~requency range o~ 10 to 200 kHz to break oil-in-water 20 emulsions.
US-A-2257997 also shows the use of ultrasonics in breaking oil-water emulsions. Sonic waves have been used in a hollow chamber of uniform cross-section to separate components of a fluid mixture as described in US-A-4280823.
US-A-4339247 describes the use of an acoustic LL~ j,C~
attached to a hollow chamber that generates acoustic energy which separates dissolved gases from liquids i~lLLuluced into the hollow chamber.
US-A-4411814 teaches the use of polyamines and/or polyamine 30 salts as d 1 c; ~ ers.
US-A-4737265 teaches the use of oxyalkylated alkyl-phenol fnrr~ hyde resins as demulsifiers.
The present invention provides an effective and ec~nf-ic;ll method to enhance brealcing 1 c j ~-nC containing oil and water.
According to one aspect of the present invention there is provided a method for breaking an ~ 1 ci ~n comprising oil and water into oil and water phases, comprising subjecting the W0 95/34522 21 8 ~ PCT/US95/07604 emulsion to sonic acoustic energy in the frequency range of about l. 0 to 10 . 0 kHz to enhance breaking the emulsion into a water phase and an oil phase.
Advantageously, the method further comprises adding a 5 rhr~m;~Al ~ l~ifi~r to the ~llq;on, preferably before subjecting it to the sonic acoustic energy.
The rh~m;r::ll Cll lR;f;er is desirably selected from the group consisting of quaternary ;I~m chloride/polyolsr cationic quaternary amines and polyoxylated phenolic 10 resinls~llrhnnAteslpolyols.
The rh~m;C~l demulsifier may be present at ~ull~e~lLL~ltions up to 0.1 percent by volume based on the volume of the emulsion.
The 1 c; nn is prefer2bly heated to a predetPrm; n~d temperature prior to step adding the demulsifier.
Advantageously, the method further comprises separating the water from the oil phase. The separation of the water phase and the oil phase is preferably r~nhAnrr~A by heating the mixture to a t~ ~LUL'2 in the range 20C to 82C: when the oil is a light oil having an API gravity greater than 20, this temperature is 20 preferably in the range 20C ~o 65OC; when the oil is a heavy oil having an API gravity of 20 or less, this temperature is preferably in the range 45C to 82C.
The method works best using when the frequency of the sonic acoustic energy is 1.25 kHz.
The l cio~ may be a water-in-oil emulsion or an oil-in-water 1 c; .~
In a particularly preferred r~mhorl;~ ~ the emulsion is injected into a hollow chamber of uniform cross-section having upper and lower flat surfaces and a pair of sides wherein the 30 distance between the upper and lower surface is substantially less than the distance between the pair of sides, and the sonic energy is produced in the hollow chamber by means of an acoustic tr~nc~llr~r attached to the upper or lower outer surface of the hollow chamber thereby r'nhAnC; nq the breaking of the emulsion 35 into a water phase and an oil phase.
Preferably, the ~Leuuen-.y of the acoustic trAncrl~lrr~r is the resonant ~ ~uut:nuy. Preferably also, the acoustic tr?nc-l-lr~r is Wogsl34s22 ~ $4Ig1 r~ 604 attached to the mid-section of the outer upper or lower surface of the chamber.
According to another aspect of the present invention there i5 provided apparatus for separating an: 1 c; nll comprising oil 5 and water into oil and water phases, comprising:
(a) a hollow chamber having an entrance port, said ~ L ~Ilce port having upper and lower surf aces and a pair of side6 wherein the distance between the upper and lower surfaces taper to a fixed distance and wherein the distance between the 5ide5 increase to a fixed distance forming an ~ LL~nCe zone;
(b) an acoustic zone ~ ;rAting with the entrance zone having upper and lower flat surfaces and a pair of sides, said distance between the upper and lower surfaces being substantially less than the distance between the pair of sides, said acoustic zone having a uniform cross-E~ctinnAl area substantially equal to the cross-sectional area of the e:~lLL-~lce port;
(c) an exit zone communicating with the acoustic zone and an exit port ~_ ; cating with the exit zone, said exit zone and exit port being a mirror image of the ~LL~ port and entrance zone; and d) a trAnc~ r~r attached to the upper or lower outer surface of the acoustic zone to generate sonic energy in the frequency range of about 1. O to lO . O kllz .
Preferably, the acoustic zone is generally rectangular in shape. The trAnC~ r is preferably attached to the mid-section of the upper or lower outer surface of the acoustic zone.
Desirably, the area of the upper and lower surfaces of the acoustic zone is substantially 48 sguare inches (0.03 m2). The th;rl~n~c~:: of the acoustic zone is preferably in the range of 0.125" (0.3 cm) to 0.75" (l.9 cm).
It is preferred that the entrance port, the entrance zone, the acoustic zone, the exit zone and the exit port are welded 35 together. It is also preferred that the apparatus is formed by f lattening the tube in the centre portion thereof .
Reference is now made to the ~' ~ ying drawings, in wo 9s/34522 PcrluS9sl0760~
which: ~
Fig. 1 is a f low sheet schematically illustrating a preferred ~Loct:duLe for treating a petroleum well stream in accordance with the inYention;
Fig. 2 is a side elevation view of a preferred ~mhc~q;r of the acoustic chamber;
Fig. 3 is a top elevation view of the acoustic chamber of Fig. 2; and Fig. 4 is a diagram of the acoustic tranRr~ r.
Referring to Fig~ 1, an emulsion of the water-in-oil type containing heavy crude oil having an API gravity of 20 or less and water is produced from a production well or wells and is introduced through line 10 into a free water knock out (FWK0) drum 12 where it is allowed to settle to separate the free water 15 by gravity separation from the water-in-oil emulsions. The water in the heavy oil is generally present in the form of a water-in-oil l ~i nn and ~ree water. Usually such 1 Ri~lnR
will contain from about 10 to 90% wt% water based on the weight of the lR;~n. Just prior to the FWK0 drum 12, a small volume 20 (about 2%) of recycled light hydrocarbon cnn~lPnR~te is injected into line 10 via line 14 to improve the flow properties of the heavy oil/~ ; nn .
About 40% of the free water is separated from the water-in-oil emulsion in the FW~C0 drum 12 by gravity separation and 25 recovered as a lower phase through line 16. The upper phase water-in-oil emulsion is removed from the FWK0 drum 12 through line 18 and a ~h~m;c~l demulsifier additive is injected into the water-in-oil 1c;or~ through line 20 to break the ~m--lRi~-n.
The additive may be used in any effective amount up to about 0.1 30 vol% of the emulsion: preferably about 0.0125 to about 0.075 vol% .
The mixture is then fed through an acoustic chamber 22 wherein the water-in-oil lRin~/additive mixture is subjected to a low frequency within the sonic range of about 1.0 to lO.0, 35 preferably 1.25 kHz, that increases or Pnh~nc~R the rate of breaking the emulsion. The flow rate into the acoustic chamber is about 1000 to 3000 barrels per day, preferably 2000 barrels wo 95/34~22 PCTiUS95/07604 2~8~g~ ~
per day. The acoustic, or sonic, energy needed to enhance breaking the water-in-oil emulsion is in the low frequency sound spectrum. Drn~l;n~ on the resonant frequency of the sonic power, the required frequency may range from 500 hertz ~Hz) to 5 lO kilohertz ~kHz). Operating at the resonant frequency of the sonic source is desirable, because maximum amplitude, or power, is maintained at this frequency. Typically, this frequency is from 1. 0 kHz to lO. 0 kHz for the desired equipment, preferably 1. 25 kHz .
Sonic energy in the low frequency range onhAnroq separation of the water-in-oil emulsions by the following r- Ani~
efficient mixing of ~-h~iCAl demulsifiers without re-emulsification of the water and oil resulting in reduced interfacial tension; 2) violent mixing action is exerted on the 15 individual water droplets resulting in the droplets of water ~-oAlo~c;n~ at a greater rate into a water phase; 3) lowering interfacial tension and viscosity; 4) fast llo~Accin r of fluid;
5) separating solids and water by difference in density; 6) dispersing and oil wetting solids which remain in or, diffused 20 into the oil phase; and, 7) destabili2ing the oil/waterlsolids interf ace to promote separation .
The broken emulsion cnntA;n;n~ the water phase and oil phase exiting the acoustic flow chamber 22 is then fed into an oil-water separator tank 24 via line 26 where the emulsion is 25 heated to a t~ "~UL~: in the range of 45C to 82C, and is allowed to settle to separate the water phase from the oil phase by gravity separation. The oil-water separator tank 24 is essentially a large vessel wherein an emulsion is heated by ae.l heater tubes and travels over trays or through a 30 filtering medium to separate oil and water. Water is recovered from the separator tank 24 as a lower phase and withdrawn through line 28. Oil is recuv~led from the separator tank 24 as an upper phase and withdrawn through line 30.
The oil recovered from ~ettl; n~ tank 24 contains about 1 35 to 5 wt% water. If desired, a plurality of separator tanks may be used in parallel to separate the oil from the water. Average rocj~lonl~e time of oil in a separator tank is in the order of W0 9S/34522 P~ Ya/u l6û~
~f ~lg` I
about 1. 5 to 4 hours.
The oil is then passed through line 30 to a series of flash drums 32 where the oil is heated to a temperature of about 125C. In the flash drums 32 any r ;ning water and light 5 hydrocarbons are flashed off to an oil/water separatOr (not shown) where they are cnnrlPnced and separated by gravity separation. The resulting recovered light llyd~uuaLLull are then recycled into the heavy water-in-oil emulsion in line 10 to improve the flow properties of the heavy oil/emulsion.
The heavy oil, containing less than 0.5 wt% water, is withdrawn from the fla5h drums 32 via line 34 and fed to a shipping tank 3 6 .
Figs. 2 and 3 depicts the acoustic chamber 22: it consists of an entrance port 38 with external screw threads 40 for 15 connection with line 18. Referring to Fig. 2, the distance between the upper and lower surf aces 4 2 and 4 4 of the entrance port 38 taper to a fixed distance 46. Referring to Fig. 3, the distance between both sides 48 of the entrance port 38 increase to the fixed position 46 to form an entrance zone 50. EIILL~ C~
20 zone 50 is connected to an acoustic zone 52. Referring to Fig.
2, acoustic zone 52 is enclosed by upper and lower flat surfaces 54 and 56 and as shown in Fig. 3, a pair of sides 58. The sides 58 of the acoustic zone 52 may, ~or example, be flat, arcuate or pointed.
Acoustic zone 52 is of uniform cross-section and the cross-sectional area is substantially equal to the cross-sectional area of entrance port 38 to prevent any chance of turbulence and r~ lcion of the oil and water. The thi~-knf~cc of the. acoustic zone 52 is substantially less than the width of the upper and 30 lower surfaces 54 and 56.
The other end of the acoustic chamber 22 is provided with an exit zone 60 and an exit port 62 which are mirror images of entrance zone 50 and entrance port 38. Exit port 62 is also provided with external screw threads 64 for rrlnnPct;on to line 35 26.
A transducer 64 is attached to the upper surface 54 of the acoustic zone 52, preferably in the mid-section of the upper _ _ _ _ _ _ _ _ _ _ _ _ _ WO 95/34522 218 4 ~ 9 1 ; PCT/US95/0760~
surface. The dimensions of the acoustic zone 52 are nominal, but are proportionate to the size and power output of the driving tr;lnc~ r 64. R~ 'Fd dimensions of the upper and lower surfaces 54 and 56 of the acoustic zone 52 are about 6l' 5 to 8" (15 cm to 20 cm~ length and about 6 to 8" (15 cm to 20 cm) width; and the L~ '^1 thickness of the acoustic zone 52 is about 0.125" to 0.75" (0.3 cm to 1.9 cm), preferably 0.375"
( o . 95cm) -The length of the entrance zone 50 and exit zone 60 is 10 proportional to the outside diameter (OD) of the entrance port 38 and the width 47 of the acoustic zone 52 to maintain laminar f low. The diameter of the entrance port 38 will vary ~l~.r~nfl i n~
upon the diameter of the existing piping in the plant connected to the acoustic chamber 22.
The acoustic chamber 22 may be fabricated from stainless steel or other materials by conventional means or formed by flattening metal tubing.
The sonic energy is y~n~:Lc~ted by a tr In~dllr~r 64 of the electrical-aCOUStiC type adapted to convert electrical energy 20 into -nif~l vibrations that are introduced into the acoustic zone 52. The upper and lower flat surfaces 54 2nd 56 of the acoustic zone 52 function as plates that contain the acoustic energy. The tr~nc~ r 64 is a magnetostrictive LL~ c~
A suitable trAnC~l~lcPr is manufactured under the trade 25 designation "T"-Motor by Sonic Research Corporation, Moline, T~l;nn;~, that generates sonic vibrations having a frequency within the range of about 1. 0 to 10 . O kHz .
In the ~mho~ t of Fig . 4, the LL r~ ~ r consists of a r-~nPtostrictive material in the form of rods 66 . æssed 30 together and wrapped with a wire coil 68. The opposite ends 70 and 72 of rod 66 abut p~rr-n.ont magnets 74 and 76 respectively.
The end 76 of rod 66 is abutted hy a pre-stress washer 78 and connected to actuator rod 80. The coil 68, magnet 74 and pre-stress washer 78 are encased in a casing 82. The rods 66 35 comprise 90% iron, 5~ terbium and 596 dysprosium sold under the trade designation "Terfenol-D" by Edge Technologies, Inc., Ames, Iowa. The Terfenol-D rod is the only ma~erial known that can Wo 95/34s22 PcrluS9S/07604 ~184~1 0 produce variable f requency, and withstand hi;gh temperature and pressure .
The rods vibrate lengthwise when a DC current flows through the coil 68. The induced magnetic field causes the rods to 5 expand and contract, i.e- maynetostrictive motion. This motion, or vibration, generates an acoustic wave or sonic energy having a frequency in the range of 0. 5 to 10 . O kHz which extends forward from the tr~n~ rPr for some distarlce. The tr~n~ r~r is powered by a 5tandard frequency generator and a power 10 amplifier. A suitable transducer for use in the present invention is disclosed in US-A-4907209.
The rhPmir~l demulsifier may be any one selected from those which can be employed to assist in the breaking and separating of water and oil phase from 1~; nnc:, Preferably, the 15 ~ ;fier is selected from the group consisting of quaternary ill~ chloride/polyols sold by Baker Performance Chemicals Inc. of Hou8ton, TX, under the tradename AQUANOX 9EB-371, cationic quaternary amines sold by Baker Performance Ch~mir~
Inc., of Houston, TX, under the tradename AQUANOX 9EB-272 and 20 polyoxylated phenolic resin/~ulrhnnilte/polyols 501d by Baker PerformanCe ('h~mir~lq, Inc., o~ Houston, TX, under the tradename AQUANOX 9 EB- 3 9 5 .
In an alternate ~mho~l;r t of the invention, if the emulsion contains light oil having an API gravity greater than 25 20, the ~ inn can be broken by subjecting it to acoustic energy in the fre~uency range of about 1. 0 to 10_ 0 kHz, preferably 1.25 kHz, without the addition of a rh~m;cll d l~;fier. In the practice of this alternate ~ L, the steps of the method would be the same as previously described 30 except for the step of adding a chemical demulsifier and heating the broken emulsion in the oil-water separator tank 24 to a lower t~ L~LUl~ in the range of about 200C to about 650C.
The present invention results in at least a reduction of 75% of chemical d l~ifier normally used to break water-in-oil 35 emulsions produced from oil fields in addition to reducing heating costs. The present invention provides a very effective method for Pnh~rlrin~ breaking water-in-oil emulsions that is WO 95/34522 2 ~ g ~ /U~ ,~ /604 more er-nnn-ir-~l and efficient than other methods presently in use. For example, 1, 570 barrels of a produced water-in-oil l1~inn containing 50% water using a ~-hPm;cAl demulsifier additive Pnh~n~P~l with acoustic energy in the low frequency 5 range re~uired 37.5 litres per day less of the chemical additive to break the emulsion than when using conventional mean6.
Decreasing the amount of additives required to break water-in-oil: 1 cinnC saves mi l l i nnC of dollars each year. In addition, the use of low frequency sonic acoustic energy to enhance 10 breaking water-in-oil lcion~- also significantly reduces the amount of heat required to separate the oil phase from the water phase after the: l cinn ha5 been broken since the emulsion is more ef f iciently coalesced and broken in the presence of low frequency sonic energy. Therefore, the present invention 15 significantly reduces rhemi~l treating and heating costs for breaking water-in-oil emulsions.
The following example describes more fully the present method. However, this example is given for illustration and are not intended to limit the invention.
Exam~le Example for Emulsion Treating with Acoustic Energy at 1.25 kHz:
First Day: Acoustic energy unit installed and system equilibrated; an oil field water-in-oil Pmlll cj nn containing 25 about 90% water was fed into a free water knock out (FWKO) drum.
In the FWK0 drum the e~ inn was allowed to settle to separate the free water from the emulsion by gravity separation. The water-in-oil lr^inn fluid flow from the free-water knock out (FW~O) drum was heated to a temperature of about 40C to about 30 42C and then fed into an oil-water separator tank at the rate of 1,510 barrels/day (B/D); AQUANOX 272 dc . lc;fier chemical additive was injected into the water-in-oil emulsion at the rate of 50 litres/day (L/D) prior to the separator tank. The chemically treated emulsion injected into the separator tank 35 was heated to about 80 to 82C and the average rPci-lPn, e time in the s~phLrlt.uL tank was 4.8 hours for the water phase and 13.4 hours for the oil phase.
WO 95134522 , ` P~ /60~
21841gl j Y o Second Day~ n flow from the FWKO drum (heated to 40 to 42C) was maintained at 1,510 barrels/day, chemical addition (AQUANOX 272) was reduced to 25 litres/day and the water-in-oil n was subj ected to acoustic energy at 1. 25 kHz prior to 5 the separator. Separated water was clean in the separator tank and oil was free of water.
Third day: Acoustic energy unit turned off and ~h~m;~
additive (AQUANOX 272) rate had to be increased to 50 litres/day to break the: l ~1 on. The water in the separator tank was 10 dirty and the separation of water and oil in the separator tank was ~;ffiC-llt with water l ;n;n~ in the emulsion.
Fourth day: Acoustic energy unit turned back on at a frequency of 1. 25 kHz which allowed the chemical additive (AQUANOX 272) rate to be reduced to 15 litres/day to break the 15 emulsion. This resulted in clean water and a clean oil/water separation in the separator tank. Basic sediment and water ~BS&W) analysis was zero with a small amount of solids in the oil. Chemical additive injection was then discontinued for 8 hours. BSfiW indicated a small amount of water in the separated 20 oil; ~ ed rh~m;cAl additi~e (AQUANOX 272) injection to 25 litres/day .
Fift_ day: The water/oil interface in the separator tank was clean and free of solids; l-h~m~c~l additive (AQUANOX 272) rate maintained at 25 litres/day and emulsion subjected to 25 acoustic energy at a frequency of 1-25 kHz. Observed clean water in separator tank, good oil/water separation and no water present in BSfiW tests. solids were oil-wet and carried over with the oil to the f lash drum.
In the above example, the average amount of residual water 30 in the oil recovered from the separator tank without acoustic treatment was about 1-5 wt%, but when acoustic energy was applied at a frequency of 1.25 kHz, residual water was not detectable in the oil Le. uv~red from the separator tank. The above example shows that when the f~h~;C;~l demulsifier additive 35 is reduced and acoustic energy is not applied the water-in-oil emulsion was not efficiently broken, but when acoustic energy was applied in conjunction with a reduced amount of chemical Wo ssl34s22 2 ~ 8 ~19 1 r~ /60~
lPm~ ier additive, breaking of the emulsion was efficient.
Also, the residence time of the fluids in the separator tank was signif icantly reduced with the application of acoustic energy at a frequency of l. 25 kHz in conjunction with the addition of 5 a reduced amount of the ~h~mi~ l d~ lci~ier additive. In fact the oil entering the separator tank was normally free of water and the water was also free of solids.
This invention relates to a method and apparatus f or breaking hydrocarbon emulsions, particularly hydrocarbon 1 ci rn~ containing oil and water into separate phases . More 5 particularly, the present invention relates to a method and apparatus for PnhAnrinj the separation of water-in-oil ~ ,nc containing petroleum recovered from und~LyLoulld reservoirs into water and crude oil phases by employing sonic acoustic energy in the fre~uency range of about l. 0 to 10. 0 kHz whether alone 10 or in conjunction with chemical demulsifiers.
In oil fields, water usually is co-produced with crude oil and becomes entrained with the oil to become an l ~io~ . The crude oil must generally be free of water (0.5% or less) before it can be sold and LLalla~uL ~ed in pipelines. The complexity of 15 separating mixtures of water and oil depends upon the physical form of the water. Where the mixture has only "free" water, the water will separate readily from the oil because of the differences in gravities of the water and oil. This type of separation ~Lest:llL5 no problem other than providing a vessel in 20 which water-oil phase separation can occur. However, the water can be dispersed L1ILUU~11UUL the oil in very minute particles, usually with ~; i Prs less than 25 microns. This mixture may be termed an lr~i.,n and is very difficult to separate into water and oil phases.
In these emulsions, the small particles of water are dispersed in the oil in a stable condition for several reasons.
First, the area of the interface between oil and water in a stable emulsion is very substantial. For example, the interfacial area of one gallon (0.005 m3) of water dispersed within oil would range from about 1,000 to 300,000 s~uare feet (93 to 28000 m2). The interfacial area of the water in the oil is stabilized against rOAlPCrPnrP by two factors in a stable emulsion. The minute size of the dispersed water is one factor to provide an ai ,~-re nPcPC:cAry for emulsion stability. The 3~ second factor is the ~L~s~n-~ of emulsifying agents or surfactants which completely coat the interfacial area to form a protective high-viscosity film that :~uLLuul~ds and stabilizes Wo 95/34522 PCTn~Ss5/07604 218~gl , O
the dispersed water within the continuous oil phase- This film prevents the coalescence of the disper5ed water in the emulsion into separate water and oil phases.
The breaking of emulsions in which water is dispersed in 5 the continuous crude oil phase requires performing certain functions. Initially, the interfacial protective film ~uLLuul.ding the dispersed water within the : l cion must be weakened or dl::,LLuyed. Then, the particles of water must rn;l l ~ccP into droplets of water which can undergo settling 10 through the effects of gravity- Thereafter, the rn~ cce~
droplets of water àre separated as a water phase from the oil phase .
Breaking of emulsions may be achieved by physical and ~-h~ c~ l treatments, application of heat, and electrical 15 methods. Generally, the methods for breaking a water-in-oil emulsions usually employ a combination of these treatments. In many instances, rhPmir~l 1 lCi~iers may be employed for assisting in the breaking of the protective film which 2~ULLUUlldS
the dispersed water. The d lc;fiers are added to the: lc~n 20 to counter-act the effects of the emulsifiers which provide the 6tability of the dispersed water particles in the continuous oil phase. The demulsifier is uniformly distributed throughout the lci~-~ so as to be present at all interfaces between the water and oil before the emulsion is processed in a treating facility.
There are a multitude of complex ~!hf-rniCAl Compositions which serve as ~' lcifiers for breaking water-in-oil emulsions.
Surf ace-active materials have been used successfully as ,1 lcifiers. The ~ mlllc;fi~rs usually have a variety of polar ,- -ntS with a ~uLeLeLLad solubility ranging from 30 pre~' ;n~ntly oil-soluble to prP~ln~in~ntly water-soluble An emulsifying agent st~h; l; ~ec an ~ l ci ~ which effect can be counteracted by a demulsif ier .
The selection of a d l c; fier for breaking a particular emulsion may be based upon actual tests and trials performed in 35 the : 1 c; r~ . Several methods are available to screen the ~ lc;flers, Usually the type of the d lCif;.~.-, and its amount in use, are best est~hl;cho~ by e~perimentatiOn directly ~ 4~9~
at the facility used to separate the emulsion into water and oil phases .
Many types of organic and inorganic materials help stabilize emulsionS. Inorganic solids such as 5and, clays, iron 5 sulphide, rust, etc. stabilize water-in-oil - lc;~nc, In addition, organic solids such as asphaltenes and paraffin can also provide 5tability to lcinnc, Chemical6, for example cationic and anionic surfactants, are commonly added to ~Luduced f luids in order to break emulsions in the oil ~ield . Heat and 10 r-~h~n;rll methods are al50 commonly used alone, or in conjunction with chemicals to dest~h; 1 i 7e and break ~ 1 c jx~n~
into oil and water phases. Millions of dollars are 5pent each year in chemical treating and heating costs for control of cm1l1 ci nn~, US-A-3200567 flicrlosPc the use of ultra50nic treatment in the frequency range of 200 kHz to 400 kHz to break oil-water c lci~nc in a continuous flow treatment.
US-A-3594314 rliccl~c~c the use of ultrasonic treatment in the ~requency range o~ 10 to 200 kHz to break oil-in-water 20 emulsions.
US-A-2257997 also shows the use of ultrasonics in breaking oil-water emulsions. Sonic waves have been used in a hollow chamber of uniform cross-section to separate components of a fluid mixture as described in US-A-4280823.
US-A-4339247 describes the use of an acoustic LL~ j,C~
attached to a hollow chamber that generates acoustic energy which separates dissolved gases from liquids i~lLLuluced into the hollow chamber.
US-A-4411814 teaches the use of polyamines and/or polyamine 30 salts as d 1 c; ~ ers.
US-A-4737265 teaches the use of oxyalkylated alkyl-phenol fnrr~ hyde resins as demulsifiers.
The present invention provides an effective and ec~nf-ic;ll method to enhance brealcing 1 c j ~-nC containing oil and water.
According to one aspect of the present invention there is provided a method for breaking an ~ 1 ci ~n comprising oil and water into oil and water phases, comprising subjecting the W0 95/34522 21 8 ~ PCT/US95/07604 emulsion to sonic acoustic energy in the frequency range of about l. 0 to 10 . 0 kHz to enhance breaking the emulsion into a water phase and an oil phase.
Advantageously, the method further comprises adding a 5 rhr~m;~Al ~ l~ifi~r to the ~llq;on, preferably before subjecting it to the sonic acoustic energy.
The rh~m;r::ll Cll lR;f;er is desirably selected from the group consisting of quaternary ;I~m chloride/polyolsr cationic quaternary amines and polyoxylated phenolic 10 resinls~llrhnnAteslpolyols.
The rh~m;C~l demulsifier may be present at ~ull~e~lLL~ltions up to 0.1 percent by volume based on the volume of the emulsion.
The 1 c; nn is prefer2bly heated to a predetPrm; n~d temperature prior to step adding the demulsifier.
Advantageously, the method further comprises separating the water from the oil phase. The separation of the water phase and the oil phase is preferably r~nhAnrr~A by heating the mixture to a t~ ~LUL'2 in the range 20C to 82C: when the oil is a light oil having an API gravity greater than 20, this temperature is 20 preferably in the range 20C ~o 65OC; when the oil is a heavy oil having an API gravity of 20 or less, this temperature is preferably in the range 45C to 82C.
The method works best using when the frequency of the sonic acoustic energy is 1.25 kHz.
The l cio~ may be a water-in-oil emulsion or an oil-in-water 1 c; .~
In a particularly preferred r~mhorl;~ ~ the emulsion is injected into a hollow chamber of uniform cross-section having upper and lower flat surfaces and a pair of sides wherein the 30 distance between the upper and lower surface is substantially less than the distance between the pair of sides, and the sonic energy is produced in the hollow chamber by means of an acoustic tr~nc~llr~r attached to the upper or lower outer surface of the hollow chamber thereby r'nhAnC; nq the breaking of the emulsion 35 into a water phase and an oil phase.
Preferably, the ~Leuuen-.y of the acoustic trAncrl~lrr~r is the resonant ~ ~uut:nuy. Preferably also, the acoustic tr?nc-l-lr~r is Wogsl34s22 ~ $4Ig1 r~ 604 attached to the mid-section of the outer upper or lower surface of the chamber.
According to another aspect of the present invention there i5 provided apparatus for separating an: 1 c; nll comprising oil 5 and water into oil and water phases, comprising:
(a) a hollow chamber having an entrance port, said ~ L ~Ilce port having upper and lower surf aces and a pair of side6 wherein the distance between the upper and lower surfaces taper to a fixed distance and wherein the distance between the 5ide5 increase to a fixed distance forming an ~ LL~nCe zone;
(b) an acoustic zone ~ ;rAting with the entrance zone having upper and lower flat surfaces and a pair of sides, said distance between the upper and lower surfaces being substantially less than the distance between the pair of sides, said acoustic zone having a uniform cross-E~ctinnAl area substantially equal to the cross-sectional area of the e:~lLL-~lce port;
(c) an exit zone communicating with the acoustic zone and an exit port ~_ ; cating with the exit zone, said exit zone and exit port being a mirror image of the ~LL~ port and entrance zone; and d) a trAnc~ r~r attached to the upper or lower outer surface of the acoustic zone to generate sonic energy in the frequency range of about 1. O to lO . O kllz .
Preferably, the acoustic zone is generally rectangular in shape. The trAnC~ r is preferably attached to the mid-section of the upper or lower outer surface of the acoustic zone.
Desirably, the area of the upper and lower surfaces of the acoustic zone is substantially 48 sguare inches (0.03 m2). The th;rl~n~c~:: of the acoustic zone is preferably in the range of 0.125" (0.3 cm) to 0.75" (l.9 cm).
It is preferred that the entrance port, the entrance zone, the acoustic zone, the exit zone and the exit port are welded 35 together. It is also preferred that the apparatus is formed by f lattening the tube in the centre portion thereof .
Reference is now made to the ~' ~ ying drawings, in wo 9s/34522 PcrluS9sl0760~
which: ~
Fig. 1 is a f low sheet schematically illustrating a preferred ~Loct:duLe for treating a petroleum well stream in accordance with the inYention;
Fig. 2 is a side elevation view of a preferred ~mhc~q;r of the acoustic chamber;
Fig. 3 is a top elevation view of the acoustic chamber of Fig. 2; and Fig. 4 is a diagram of the acoustic tranRr~ r.
Referring to Fig~ 1, an emulsion of the water-in-oil type containing heavy crude oil having an API gravity of 20 or less and water is produced from a production well or wells and is introduced through line 10 into a free water knock out (FWK0) drum 12 where it is allowed to settle to separate the free water 15 by gravity separation from the water-in-oil emulsions. The water in the heavy oil is generally present in the form of a water-in-oil l ~i nn and ~ree water. Usually such 1 Ri~lnR
will contain from about 10 to 90% wt% water based on the weight of the lR;~n. Just prior to the FWK0 drum 12, a small volume 20 (about 2%) of recycled light hydrocarbon cnn~lPnR~te is injected into line 10 via line 14 to improve the flow properties of the heavy oil/~ ; nn .
About 40% of the free water is separated from the water-in-oil emulsion in the FW~C0 drum 12 by gravity separation and 25 recovered as a lower phase through line 16. The upper phase water-in-oil emulsion is removed from the FWK0 drum 12 through line 18 and a ~h~m;c~l demulsifier additive is injected into the water-in-oil 1c;or~ through line 20 to break the ~m--lRi~-n.
The additive may be used in any effective amount up to about 0.1 30 vol% of the emulsion: preferably about 0.0125 to about 0.075 vol% .
The mixture is then fed through an acoustic chamber 22 wherein the water-in-oil lRin~/additive mixture is subjected to a low frequency within the sonic range of about 1.0 to lO.0, 35 preferably 1.25 kHz, that increases or Pnh~nc~R the rate of breaking the emulsion. The flow rate into the acoustic chamber is about 1000 to 3000 barrels per day, preferably 2000 barrels wo 95/34~22 PCTiUS95/07604 2~8~g~ ~
per day. The acoustic, or sonic, energy needed to enhance breaking the water-in-oil emulsion is in the low frequency sound spectrum. Drn~l;n~ on the resonant frequency of the sonic power, the required frequency may range from 500 hertz ~Hz) to 5 lO kilohertz ~kHz). Operating at the resonant frequency of the sonic source is desirable, because maximum amplitude, or power, is maintained at this frequency. Typically, this frequency is from 1. 0 kHz to lO. 0 kHz for the desired equipment, preferably 1. 25 kHz .
Sonic energy in the low frequency range onhAnroq separation of the water-in-oil emulsions by the following r- Ani~
efficient mixing of ~-h~iCAl demulsifiers without re-emulsification of the water and oil resulting in reduced interfacial tension; 2) violent mixing action is exerted on the 15 individual water droplets resulting in the droplets of water ~-oAlo~c;n~ at a greater rate into a water phase; 3) lowering interfacial tension and viscosity; 4) fast llo~Accin r of fluid;
5) separating solids and water by difference in density; 6) dispersing and oil wetting solids which remain in or, diffused 20 into the oil phase; and, 7) destabili2ing the oil/waterlsolids interf ace to promote separation .
The broken emulsion cnntA;n;n~ the water phase and oil phase exiting the acoustic flow chamber 22 is then fed into an oil-water separator tank 24 via line 26 where the emulsion is 25 heated to a t~ "~UL~: in the range of 45C to 82C, and is allowed to settle to separate the water phase from the oil phase by gravity separation. The oil-water separator tank 24 is essentially a large vessel wherein an emulsion is heated by ae.l heater tubes and travels over trays or through a 30 filtering medium to separate oil and water. Water is recovered from the separator tank 24 as a lower phase and withdrawn through line 28. Oil is recuv~led from the separator tank 24 as an upper phase and withdrawn through line 30.
The oil recovered from ~ettl; n~ tank 24 contains about 1 35 to 5 wt% water. If desired, a plurality of separator tanks may be used in parallel to separate the oil from the water. Average rocj~lonl~e time of oil in a separator tank is in the order of W0 9S/34522 P~ Ya/u l6û~
~f ~lg` I
about 1. 5 to 4 hours.
The oil is then passed through line 30 to a series of flash drums 32 where the oil is heated to a temperature of about 125C. In the flash drums 32 any r ;ning water and light 5 hydrocarbons are flashed off to an oil/water separatOr (not shown) where they are cnnrlPnced and separated by gravity separation. The resulting recovered light llyd~uuaLLull are then recycled into the heavy water-in-oil emulsion in line 10 to improve the flow properties of the heavy oil/emulsion.
The heavy oil, containing less than 0.5 wt% water, is withdrawn from the fla5h drums 32 via line 34 and fed to a shipping tank 3 6 .
Figs. 2 and 3 depicts the acoustic chamber 22: it consists of an entrance port 38 with external screw threads 40 for 15 connection with line 18. Referring to Fig. 2, the distance between the upper and lower surf aces 4 2 and 4 4 of the entrance port 38 taper to a fixed distance 46. Referring to Fig. 3, the distance between both sides 48 of the entrance port 38 increase to the fixed position 46 to form an entrance zone 50. EIILL~ C~
20 zone 50 is connected to an acoustic zone 52. Referring to Fig.
2, acoustic zone 52 is enclosed by upper and lower flat surfaces 54 and 56 and as shown in Fig. 3, a pair of sides 58. The sides 58 of the acoustic zone 52 may, ~or example, be flat, arcuate or pointed.
Acoustic zone 52 is of uniform cross-section and the cross-sectional area is substantially equal to the cross-sectional area of entrance port 38 to prevent any chance of turbulence and r~ lcion of the oil and water. The thi~-knf~cc of the. acoustic zone 52 is substantially less than the width of the upper and 30 lower surfaces 54 and 56.
The other end of the acoustic chamber 22 is provided with an exit zone 60 and an exit port 62 which are mirror images of entrance zone 50 and entrance port 38. Exit port 62 is also provided with external screw threads 64 for rrlnnPct;on to line 35 26.
A transducer 64 is attached to the upper surface 54 of the acoustic zone 52, preferably in the mid-section of the upper _ _ _ _ _ _ _ _ _ _ _ _ _ WO 95/34522 218 4 ~ 9 1 ; PCT/US95/0760~
surface. The dimensions of the acoustic zone 52 are nominal, but are proportionate to the size and power output of the driving tr;lnc~ r 64. R~ 'Fd dimensions of the upper and lower surfaces 54 and 56 of the acoustic zone 52 are about 6l' 5 to 8" (15 cm to 20 cm~ length and about 6 to 8" (15 cm to 20 cm) width; and the L~ '^1 thickness of the acoustic zone 52 is about 0.125" to 0.75" (0.3 cm to 1.9 cm), preferably 0.375"
( o . 95cm) -The length of the entrance zone 50 and exit zone 60 is 10 proportional to the outside diameter (OD) of the entrance port 38 and the width 47 of the acoustic zone 52 to maintain laminar f low. The diameter of the entrance port 38 will vary ~l~.r~nfl i n~
upon the diameter of the existing piping in the plant connected to the acoustic chamber 22.
The acoustic chamber 22 may be fabricated from stainless steel or other materials by conventional means or formed by flattening metal tubing.
The sonic energy is y~n~:Lc~ted by a tr In~dllr~r 64 of the electrical-aCOUStiC type adapted to convert electrical energy 20 into -nif~l vibrations that are introduced into the acoustic zone 52. The upper and lower flat surfaces 54 2nd 56 of the acoustic zone 52 function as plates that contain the acoustic energy. The tr~nc~ r 64 is a magnetostrictive LL~ c~
A suitable trAnC~l~lcPr is manufactured under the trade 25 designation "T"-Motor by Sonic Research Corporation, Moline, T~l;nn;~, that generates sonic vibrations having a frequency within the range of about 1. 0 to 10 . O kHz .
In the ~mho~ t of Fig . 4, the LL r~ ~ r consists of a r-~nPtostrictive material in the form of rods 66 . æssed 30 together and wrapped with a wire coil 68. The opposite ends 70 and 72 of rod 66 abut p~rr-n.ont magnets 74 and 76 respectively.
The end 76 of rod 66 is abutted hy a pre-stress washer 78 and connected to actuator rod 80. The coil 68, magnet 74 and pre-stress washer 78 are encased in a casing 82. The rods 66 35 comprise 90% iron, 5~ terbium and 596 dysprosium sold under the trade designation "Terfenol-D" by Edge Technologies, Inc., Ames, Iowa. The Terfenol-D rod is the only ma~erial known that can Wo 95/34s22 PcrluS9S/07604 ~184~1 0 produce variable f requency, and withstand hi;gh temperature and pressure .
The rods vibrate lengthwise when a DC current flows through the coil 68. The induced magnetic field causes the rods to 5 expand and contract, i.e- maynetostrictive motion. This motion, or vibration, generates an acoustic wave or sonic energy having a frequency in the range of 0. 5 to 10 . O kHz which extends forward from the tr~n~ rPr for some distarlce. The tr~n~ r~r is powered by a 5tandard frequency generator and a power 10 amplifier. A suitable transducer for use in the present invention is disclosed in US-A-4907209.
The rhPmir~l demulsifier may be any one selected from those which can be employed to assist in the breaking and separating of water and oil phase from 1~; nnc:, Preferably, the 15 ~ ;fier is selected from the group consisting of quaternary ill~ chloride/polyols sold by Baker Performance Chemicals Inc. of Hou8ton, TX, under the tradename AQUANOX 9EB-371, cationic quaternary amines sold by Baker Performance Ch~mir~
Inc., of Houston, TX, under the tradename AQUANOX 9EB-272 and 20 polyoxylated phenolic resin/~ulrhnnilte/polyols 501d by Baker PerformanCe ('h~mir~lq, Inc., o~ Houston, TX, under the tradename AQUANOX 9 EB- 3 9 5 .
In an alternate ~mho~l;r t of the invention, if the emulsion contains light oil having an API gravity greater than 25 20, the ~ inn can be broken by subjecting it to acoustic energy in the fre~uency range of about 1. 0 to 10_ 0 kHz, preferably 1.25 kHz, without the addition of a rh~m;cll d l~;fier. In the practice of this alternate ~ L, the steps of the method would be the same as previously described 30 except for the step of adding a chemical demulsifier and heating the broken emulsion in the oil-water separator tank 24 to a lower t~ L~LUl~ in the range of about 200C to about 650C.
The present invention results in at least a reduction of 75% of chemical d l~ifier normally used to break water-in-oil 35 emulsions produced from oil fields in addition to reducing heating costs. The present invention provides a very effective method for Pnh~rlrin~ breaking water-in-oil emulsions that is WO 95/34522 2 ~ g ~ /U~ ,~ /604 more er-nnn-ir-~l and efficient than other methods presently in use. For example, 1, 570 barrels of a produced water-in-oil l1~inn containing 50% water using a ~-hPm;cAl demulsifier additive Pnh~n~P~l with acoustic energy in the low frequency 5 range re~uired 37.5 litres per day less of the chemical additive to break the emulsion than when using conventional mean6.
Decreasing the amount of additives required to break water-in-oil: 1 cinnC saves mi l l i nnC of dollars each year. In addition, the use of low frequency sonic acoustic energy to enhance 10 breaking water-in-oil lcion~- also significantly reduces the amount of heat required to separate the oil phase from the water phase after the: l cinn ha5 been broken since the emulsion is more ef f iciently coalesced and broken in the presence of low frequency sonic energy. Therefore, the present invention 15 significantly reduces rhemi~l treating and heating costs for breaking water-in-oil emulsions.
The following example describes more fully the present method. However, this example is given for illustration and are not intended to limit the invention.
Exam~le Example for Emulsion Treating with Acoustic Energy at 1.25 kHz:
First Day: Acoustic energy unit installed and system equilibrated; an oil field water-in-oil Pmlll cj nn containing 25 about 90% water was fed into a free water knock out (FWKO) drum.
In the FWK0 drum the e~ inn was allowed to settle to separate the free water from the emulsion by gravity separation. The water-in-oil lr^inn fluid flow from the free-water knock out (FW~O) drum was heated to a temperature of about 40C to about 30 42C and then fed into an oil-water separator tank at the rate of 1,510 barrels/day (B/D); AQUANOX 272 dc . lc;fier chemical additive was injected into the water-in-oil emulsion at the rate of 50 litres/day (L/D) prior to the separator tank. The chemically treated emulsion injected into the separator tank 35 was heated to about 80 to 82C and the average rPci-lPn, e time in the s~phLrlt.uL tank was 4.8 hours for the water phase and 13.4 hours for the oil phase.
WO 95134522 , ` P~ /60~
21841gl j Y o Second Day~ n flow from the FWKO drum (heated to 40 to 42C) was maintained at 1,510 barrels/day, chemical addition (AQUANOX 272) was reduced to 25 litres/day and the water-in-oil n was subj ected to acoustic energy at 1. 25 kHz prior to 5 the separator. Separated water was clean in the separator tank and oil was free of water.
Third day: Acoustic energy unit turned off and ~h~m;~
additive (AQUANOX 272) rate had to be increased to 50 litres/day to break the: l ~1 on. The water in the separator tank was 10 dirty and the separation of water and oil in the separator tank was ~;ffiC-llt with water l ;n;n~ in the emulsion.
Fourth day: Acoustic energy unit turned back on at a frequency of 1. 25 kHz which allowed the chemical additive (AQUANOX 272) rate to be reduced to 15 litres/day to break the 15 emulsion. This resulted in clean water and a clean oil/water separation in the separator tank. Basic sediment and water ~BS&W) analysis was zero with a small amount of solids in the oil. Chemical additive injection was then discontinued for 8 hours. BSfiW indicated a small amount of water in the separated 20 oil; ~ ed rh~m;cAl additi~e (AQUANOX 272) injection to 25 litres/day .
Fift_ day: The water/oil interface in the separator tank was clean and free of solids; l-h~m~c~l additive (AQUANOX 272) rate maintained at 25 litres/day and emulsion subjected to 25 acoustic energy at a frequency of 1-25 kHz. Observed clean water in separator tank, good oil/water separation and no water present in BSfiW tests. solids were oil-wet and carried over with the oil to the f lash drum.
In the above example, the average amount of residual water 30 in the oil recovered from the separator tank without acoustic treatment was about 1-5 wt%, but when acoustic energy was applied at a frequency of 1.25 kHz, residual water was not detectable in the oil Le. uv~red from the separator tank. The above example shows that when the f~h~;C;~l demulsifier additive 35 is reduced and acoustic energy is not applied the water-in-oil emulsion was not efficiently broken, but when acoustic energy was applied in conjunction with a reduced amount of chemical Wo ssl34s22 2 ~ 8 ~19 1 r~ /60~
lPm~ ier additive, breaking of the emulsion was efficient.
Also, the residence time of the fluids in the separator tank was signif icantly reduced with the application of acoustic energy at a frequency of l. 25 kHz in conjunction with the addition of 5 a reduced amount of the ~h~mi~ l d~ lci~ier additive. In fact the oil entering the separator tank was normally free of water and the water was also free of solids.
Claims (25)
1. A method for breaking an emulsion comprising oil and water into oil and water phases, comprising subjecting the emulsion to sonic acoustic energy in the frequency range of about 1.0 to 10.0 kHz to enhance breaking the emulsion into a water phase and an oil phase.
2. A method according to claim 1, further comprising adding a chemical demulsifier to the emulsion.
3. A method according to claim 2, wherein the demulsifier is added prior to subjecting the emulsion to sonic acoustic energy.
4. A method according to claim 2 or 3, wherein the chemical demulsifier is selected from the group consisting of quaternary ammonium chloride/polyols, cationic quaternary amines and polyoxylated phenolic resin/sulphonates/polyols.
5. A method according to claim 1, 2, 3 or 4, wherein the chemical demulsifier is present at concentrations up to 0.1 percent by volume based on the volume of the emulsion.
6. A method according to any one of claims 2 to 5, wherein the emulsion is heated to a predetermined temperature prior to adding the demulsifier.
7. A method according to any preceding claim, further comprising separating the water from the oil phase.
8. A method according to claim 7, wherein the separation of the water phase and the oil phase is enhanced by heating the mixture to a temperature in the range 20°C to 82°C.
9. A method according to any preceding claim, wherein the oil is a light oil having an API gravity greater than 20.
10. A method according to claim 9, when dependent upon claim 7, wherein during the separation of the water phase and the oil phase is enhanced by heating the mixture to a temperature in the range 20°C to 65°C.
11. A method according to any one of claims 1 to 8, wherein the oil is a heavy oil having an API gravity of 20 or less.
12. A method according to claim 11, when dependent upon claim 7, wherein during the separation of the water phase and the oil phase is enhanced by heating the mixture to a temperature of about 45°C to about 82°C.
13. A method according to any preceding claim, wherein the frequency of the sonic acoustic energy is 1.25 kHz.
14. A method according to any preceding claim, wherein the emulsion is a water-in-oil emulsion.
15. A method according to any one of claims 1 to 13, wherein the emulsion is an oil-in-water emulsion.
16. A method according to any preceding claim, wherein the emulsion is injected into a hollow chamber of uniform cross-section having upper and lower flat surfaces and a pair of sides wherein the distance between the upper and lower surface is substantially less than the distance between the pair of sides, and the sonic energy is produced in the hollow chamber by means of an acoustic transducer attached to the upper or lower outer surface of the hollow chamber thereby enhancing the breaking of the emulsion into a water phase and an oil phase.
17. A method according to claim 16, wherein the frequency of the acoustic transducer is the resonant frequency.
18. A method according to claim 16 or 17, wherein the acoustic transducer is attached to the mid-section of the outer upper or lower surface of the chamber.
19. Apparatus for separating an emulsion comprising oil and water into oil and water phases, comprising:
(a) a hollow chamber having an entrance port, said entrance port having upper and lower surfaces and a pair of sides wherein the distance between the upper and lower surfaces taper to a fixed distance and wherein the distance between the sides increase to a fixed distance forming an entrance zone;
(b) an acoustic zone communicating with the entrance zone having upper and lower flat surfaces and a pair of sides, said distance between the upper and lower surfaces being substantially less than the distance between the pair of sides, said acoustic zone having a uniform cross-sectional area substantially equal to the cross-sectional area of the entrance port;
(c) an exit zone communicating with the acoustic zone and an exit port communicating with the exit zone, said exit zone and exit port being a mirror image of the entrance port and entrance zone; and (d) a transducer attached to the upper or lower outer surface of the acoustic zone to generate sonic energy in the frequency range of about 1.0 to 10.0 kHz.
(a) a hollow chamber having an entrance port, said entrance port having upper and lower surfaces and a pair of sides wherein the distance between the upper and lower surfaces taper to a fixed distance and wherein the distance between the sides increase to a fixed distance forming an entrance zone;
(b) an acoustic zone communicating with the entrance zone having upper and lower flat surfaces and a pair of sides, said distance between the upper and lower surfaces being substantially less than the distance between the pair of sides, said acoustic zone having a uniform cross-sectional area substantially equal to the cross-sectional area of the entrance port;
(c) an exit zone communicating with the acoustic zone and an exit port communicating with the exit zone, said exit zone and exit port being a mirror image of the entrance port and entrance zone; and (d) a transducer attached to the upper or lower outer surface of the acoustic zone to generate sonic energy in the frequency range of about 1.0 to 10.0 kHz.
20. Apparatus according to claim 19, wherein the acoustic zone is generally rectangular in shape.
21. Apparatus according to claim 19 or 20, wherein the transducer is attached to the mid-section of the upper or lower outer surface of the acoustic zone.
22. Apparatus according to claim 19, 20 or 21, wherein the area of the upper and lower surfaces of the acoustic zone is substantially 48 square inches (0.03 m2).
23. Apparatus according to claim 19, 20, 21 or 22, wherein the thickness of the acoustic zone is in the range of 0.125" (0.3 cm) to 0.75" (1.9 cm).
24. Apparatus according to any one of claims 19 to 23, wherein the entrance port, the entrance zone, the acoustic zone, the exit zone and the exit port are welded together.
25. Apparatus according to any one of claims 19 to 24, wherein the apparatus is formed by flattening the tube in the centre portion thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US26043094A | 1994-06-15 | 1994-06-15 | |
| US08/260,430 | 1994-06-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2184191A1 true CA2184191A1 (en) | 1995-12-21 |
Family
ID=22989133
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002184191A Abandoned CA2184191A1 (en) | 1994-06-15 | 1995-06-14 | Method and apparatus for breaking hydrocarbon emulsions |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2184191A1 (en) |
| WO (1) | WO1995034522A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9708984D0 (en) * | 1997-05-03 | 1997-06-25 | Univ Cardiff | Particle manipulation |
| CN1164344C (en) * | 1999-07-26 | 2004-09-01 | 国际壳牌研究有限公司 | Breaking of oil/water emulsion |
| US7014773B2 (en) * | 2003-02-21 | 2006-03-21 | Exxonmobil Research And Engineering Company | Demulsification of emulsions by socillatory mixing |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2257997A (en) * | 1940-11-27 | 1941-10-07 | American Cyanamid Co | Breaking petroleum emulsions |
| US3200567A (en) * | 1956-09-07 | 1965-08-17 | Black Sivalls & Bryson Inc | System for the sonic treatment of emulsions and for resolving the same into their constituent parts |
| US3594314A (en) * | 1969-02-12 | 1971-07-20 | James R Bilhartz | Method of separating oil,water and solids by ultrasonic treatment |
| US4280823A (en) * | 1979-11-13 | 1981-07-28 | Honeywell Inc. | Method and apparatus for sonic separation and analysis of components of a fluid mixture |
| US5344532A (en) * | 1990-03-09 | 1994-09-06 | Joseph Adrian A | Ultrasonic energy producing device |
-
1995
- 1995-06-14 WO PCT/US1995/007604 patent/WO1995034522A1/en active Application Filing
- 1995-06-14 CA CA002184191A patent/CA2184191A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1995034522A1 (en) | 1995-12-21 |
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| Date | Code | Title | Description |
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| FZDE | Dead |