OA13264A

OA13264A - Method for reducing the viscosity of viscous fluids.

Info

Publication number: OA13264A
Application number: OA1200600112A
Authority: OA
Inventors: Michael John Crabtree; Nicholas John Crowther; Philip Fletcher; Donald Eagland
Original assignee: Proflux Systems Llp
Priority date: 2003-10-02
Filing date: 2004-09-27
Publication date: 2007-01-31
Also published as: EA015320B1; EA200600512A1; CA2931133C; CA2931133A1; CA2820427A1; GB0323067D0; GB0404051D0; CA2820427C

Abstract

The present invention relates to methods for reducing the viscosity of viscous fluids and, in particular, to reducing the viscosity of viscous fluids for easier pumping between two locations. A viscous fluid, such as heavy crude oil which is too viscous to enable it to be pumped from a flowing phase of a reservoir into and along a pipeline for delivery to a refinery or other storage facility, may be contacted with a formulation to reduce its viscosity. The formulation comprises a polymeric material AA which includes -O- moieties pendent from a polymeric backbone thereof and said material is optionally cross-linked. In one embodiment, the formulation may comprise polyvinyl alcohol. In an alternative embodiment, the formulation may comprise a cross-linked polymeric material, such as cross-linked polyvinyl alcohol. After the viscous composition has been transported to a desired location, it may be separated from the other components.

Description

1

Proflux Systems LLI

This invention relates to viscous fluids and particularly,although not e.xclusively, relates to the réduction of theviscosity of viscous fluids to facilitate their flowbetw'een two locations. Preferred embodiments relate tothe réduction of the viscosity of viscous petroleum tofacilitate its transport between a place where it isproduced and a point downstream thereof.

There are many known petroleum-containing formations fromwhich very little petroleum can be obtained by normalproduction techniques because the petroleum viscosity - isso high that 'the petroleum will not flow at formationconditions éven if a substantial pressure differential,either natural or artificially induced as by injectingwater or other fluids into the formation, is applied tothe petroleum. These petroleum formations are sometimesreferred to as heavy oil formations, and for the purposeof this disclosure, by heavy oil or viscous petroleum itis meant crude petroleum having an API gravity less thanabout 25° API at 75°F.

Various techniques hâve been disclosed for stimulating therecovery of viscous petroleum or heavy oil andfacilitating its transport along pipelines from aproduction facility to a refinery. However, there stillexists a problem, especially where the petroleum isextremely viscous such as that found in heavy oilréservoirs or tar sand deposits. 2

It is an object of the présent invention to addressproblems associated with the flow and/or transport ofviscous fluids.

According to a first aspect of the invention, there isprovided' a method of reducing the viscosity of a viscouscomposition which is arranged to flow along a fluid flowpath, said method comprising contacting the viscouscomposition with a treatment fluid formulation, saidtreatment fluid formulation comprising a polymericmatériel AA which includes -O- moieties pendent from apolymeric backbone thereof, wherein polymeric material AAis optionally cross-linked.

The ratio of the viscosity of the viscous compositionimmediately prior to contact with the .treatment fluidformulation to the viscosity after contact with thetreatment fluid formulation is preferably at least 1.2,more preferably at least 1.5.

The viscosity of the viscous composition after contactwith the treatment fluid formulation is preferably lessthan 300cP, more preferably less than 200cP, especiallyless than lOOcP measured at 25°C and 1000s'1 morepreferably when measured at 100s"1.

The viscosity of the viscous composition after contactwith the treatment fluid formulation is preferably lessthan 4000cP for ail shear rates in the range 20-lOOOs'1.

The viscous composition after contact with the treatmentfluid formulation preferably exhibits shear thinning -i.e. the viscosity preferably falls as the shear rate 3

Z. Λί*\< ί increases. This may advantageously improve the mobilityof the viscous composition. Said viscous composition mayexhibit shear thinning as aforesaid at least over theshear rate range 0.1 to 100s'1. The shear thinningproperty may facilitate the re-commencement of flow of theviscous composition after flow in the fluid path has beenstopped, for any reason. Advantageously, even if theviscous composition séparâtes from parts of the treatmentfluid formulation, for example during suspension of flowalong the fluid flow path, on commencement of flow, theviscous composition and treatment fluid formulation mayagain become intimately mixed and the viscosity may bereduced as described.

The method may be used to reduce the viscosity of manytypes of viscous compositions provided that the viscouscompositions can be caused to form a dispersion whencontacted with said treatment fluid formulation. Saidviscous composition is preferably organic. It ispreferably a viscous fluid. It is preferably an oil. Itpreferably comprises Petroleum. It preferably comprises aviscous petroleum.

Said viscous composition may be derived from a heavy oilréservoir and/or from tar sand deposits. It may bederived from a deep well wherein the composition may besufficiently warm down the well to enable it to flow; butthe viscosity rises as the composition is withdrawn fromthe well (and cools) making it more difficult to flow.

Said treatment fluid formulation preferably comprises ahydrogel, 4 13264

Said treatment fluid formulation is preferably notinjected into an injection well of a subterraneanformation in order to contact said viscous composition.

Said treatment fluid formulation is preferably initiallycontacted with said viscous composition at or downstreamof a production means, for example at or downstream of aproducing face of a subterranean formation. In oneembodiment, said treatment fluid formulation may beinitially contacted with said viscous composition belowground (for example at. or adjacent to a producing face ofa subterranean formation) to reduce the viscosity of saidviscous composition below ground and facilitate itstransport to the surface. In another embodiment, saidtreatment fluid formulation may be contacted with saidviscous composition at or adjacent the surface of theground after the viscous composition has been transportedto the surface, for example using heavy pumps.

Said treatment fluid formulation is preferably not used todrive the viscous composition through a subterraneanformation.

Said fluid flow path is preferably defined by a conduitmeans.

Said conduit means preferably includes a first conduitpart (e.g. a pipeline) which is arranged downstream of aproduction means, preferably above ground level. Saidfirst conduit part preferably contains said viscouscomposition after contact with the treatment fluidformulation. 5 •η' Π Λ h ο ζο4

Said first conduit part may be circular in cross-section.Said part may hâve a cross-sectional area for at leastpart of its length of at least 5cm, preferably at least10cm. In sonie cases, the cross-section may hâve adiameter of up to 0.5m. Said first conduit partpreferably extends away from a position where the viscouscomposition is produced, suitably in a transversedirection to the vertical. Said first conduit part mayhâve a length of at least 5m, preferably at least 20m,especially at least 100m. In some cases, said firstconduit part may hâve a length of more than 1,000m, morethan 5,000m, more than 10,000m, even more than 500km.Long pipes may be arranged to deliver petroleum to- arefinery; such pipes may extend partly above and partlybelow ground.

Said fluid flow path (e.g. said conduit means) may extendbetween a first point, remote from the point of productionof the viscous composition, and a second point doser to,for example at or adjacent to, the point of production ofthe viscous composition. Said first point may be aboveground and may be, for example, a refinery; said secondpoint may be doser to the producing face of asubterranean formation. It may be at or adjacent to theproducing face.

Said fluid flow path may be defined, in part, by a secondconduit part which extends upwardly from below ground toabove ground. Said second conduit part may be a riserpipe. Said second conduit part may contain said viscouscomposition after contact with the treatment fluidformulation.

6

Said treatment fluid formulation is preferably arranged todisperse and/or emulsify said viscous composition oncontact therewith. Said viscous composition, may not besubstantially particulate prior to contact with saidtreatment fluid formulation - it may be in the form of asubstantially homogenous fluidic mass. Preferably, flowalong said fluid flow path is turbulent, at least in part,thereby to facilitate formation of said dispersion and/orémulsion. Preferably, flow is turbulent at the point ofinitial contact of said viscous composition with saidtreatment fluid formulation so that said composition isdispersed and/or emulsified on contact with saidformulation.

In the method, a delivery flow path is preferably definedwhich is arranged to communicate with said fluid flow pathwherein said treatment fluid formulation is dosed intosaid viscous composition in said fluid flow path via saiddelivery flow path. Said delivery flow path preferablycommunicates with said fluid flow path at or downstream ofa producing face of the subterranean formation.

The ratio of the flow rate (in weight per unit time) oftreatment fluid formulation in said delivery flow path tothe flow rate (in the same units) of viscous compositionin said fluid flow path may be in the range 0.1 to 2.5,preferably in the range 0.2 to 1, more preferably in therange 0.4 to 0.8, especially in the range 0.6 to 0.7.

The mass fraction of viscous composition in said fluidflow path after contact with said treatment fluidformulation is preferably in the range 0.4 to 0.8.

7

Preferably, immediately after contact between said viscouscomposition and said treatment fluid formulation, thecomposition in said fluid flow path includes 30 to 80 wt%(preferably 40 to 80wt%, more preferably 50 to 70 wt%) ofmaterial derived from said viscous composition and 20 to70wt%, (preferably 20 to 60wt%, more preferably 30 to50wt%, especially 30 to 45wt%) of material derived fromsaid treatment fluid formulation.

Suitably, immediately after contact between said viscouscomposition and said treatment. fluid formulation, thecomposition in said fluid flow path includes at least20wt%, preferably at least 25wt%, more preferably at least30wt%, water; and at least 40wt%, preferably at least50wt%, more preferably at least 55wt% of said viscouscomposition, especially of oil.

The amount of water in the composition in said fluid flowpath immediately after contact between said viscouscomposition and said treatment fluid formulation ispreferably less than 70wt%, more preferably less than60wt%, especially less than 50wt%, more preferably 40wt%or less. The amount of water may be in the range 2 0 to50wt%.

Said treatment fluid formulation suitably has a viscosityat 25°C and 1000s"1 of greater than lcP, preferablygreater than 2cP. Said treatment fluid formulationpreferably has a viscosity under the conditions describedof not greater than 50cP, preferably of lOcP-.or less.

Said treatment fluid formulation is preferably aqueous.It may include at least 70wt%, preferably at least 80wt%,

8 more preferably at least 90wt%, especially at least 95wt%water. The amount of water may be less than 99.6wt%. Saidtreatment fluid formulation preferably includes 90 to99.6wt% water.

Said treatment fluid formulation suitably includes atleast 0.2wt%, preferably at least 0.4wt%, especially atleast 0.5wt% of said polymeric material AA. Saidformulation preferably includes less than l0wt%, morepreferably less than 8wt%, especially less than 5.5wt% ofsaid polymeric material AA. 'In a preferred embodiment, said treatment fluidformulation includes 94.5 to 99.6wt% water and 0.4 to 5.5.wt% of said polymeric material AA; and the ratio of thewt% of said treatment fluid formulation to the wt% of saidviscous composition contacted in the method is in therange 0.4 to 0.9.

Water for use in the treatment fluid formulation may bederived from any convenient source. It may be potablewater, surface water, sea water, aquifer water, deionisedproduction water and filtered water derived from any ofthe aforementioned sources. The water may be treated sothat it is suitable for use in the method. For example,it may be treated by addition of oxygen scavengers,biocides, corrosion inhibitors, scale ,inhibitors, anti-foaming agents and flow improvers. Sea water and/or waterfrom other sources may be deoxygenated and/orde sulphonated.

Said polymeric material AA is preferably soluble in waterat 25°C. Preferably, when said polymeric material AA is 9 13284 not cross-linked, polymeric material AA in said treatmentïluid formulation is wholly or partially dissolved thereinto define a solution or dispersion.

Whilst the applicant does not wish to be bound by anytheory, said optionally cross-linked polymeric material AAmay be arranged to coat particles of the viscouscomposition, whereby the coated particles may then be moreeasily dispersed compared to uncoated particles such asoil. Said polymeric material AA may be arranged to beabsorbed onto the viscous composition, for example oil, toenable said particles to form. Said polymeric material AAis preferably not a conventional surfactant having. ahydrophobie portion, for example a hydrophobie tail and ahydrophilic portion, for example an ionic head. Thus, it is believed 1 that formation of said coated particles preferably does not involve a hydrophobie tail part interacting with, for example oil, and a hydrophilic part interacting with, for example water. According to theapplicant's theory, the polymeric material AA may form"balls" made up of "threads" of the polymeric material.It is believed that a multiplicity of such balls associatewith the surface of oil droplets formed in the method, tosurround the droplets and thereby stabilise them. Whenthe polymeric material AA is cross-linked the cross-linksmay formalise the shape of the balls and make them robust.

Said polymeric backbone of polymeric material AApreferably includes carbon atoms. Said carbon atoms arepreferably part of -CH2- moieties. Preferably, a repeatunit of said polymeric backbone includes carbon to carbonbonds, preferably C-C single bonds. Preferably, saidpolymeric material AA includes a repeat unit which 1326 10 includes a -CH2- moiety. Preferably, said polymericËackbone does not include any -O- moieties, for examples -C-O- moieties such as are found in an alkyleneoxy polymer,such as polyethyleneglycol. Said polymeric backbone ispreferably not defined by an aromatic moiety such as aphenyl moiety such as is found in polyethersulphones.Said polymeric backbone preferably does not include any -S- moieties. Said polymeric backbone preferably does notinclude any nitrogen atoms. Said polymeric backbonepreferably consists essentially of carbon atoms,preferably in the form of C-C single bonds.

Said treatment fluid formulation may include a hydrogelwhich may be an optionally cross-linked polysaccharide,polyvinylalcohol or polyvinylacetate.

Said -0- moieties are preferably directly bonded to thepolymeric backbone.

Said polymeric material AA preferably includes, onaverage, at least 10, more preferably at least 50, -0-moieties pendent from the polymeric backbone thereof.Said -0- moieties are preferably a part of a repeat unitof said polymeric material AA.

Preferably, said -0- moieties are directly bonded to acarbon atom in said polymeric backbone of polymericmaterial AA, suitably so that said polymeric material AAincludes a moiety (which is preferably part of a repeatunit) of formula: 11 G3

I

Gx--C--G2 II

I o

I where G1 and G2 are other parts of the polymeric backboneand G3 is another moiety pendent from the polymericbackbone. Preferably, G3 represents a hydrogen atom.

Preferably, said polymeric material AA includes a moiety

-CH-CH2- III

I

O

I

Said moiety III is preferably part of a repeat unit. Saidmoiety III may be part of a copolymer which includes arepeat unit which includes a moiety of a different typecompared to moiety III. Suitably, at least S0 mole%,preferably at least 80 mole%, more preferably at least 90mole% of polymeric material AA comprises repeat unitswhich comprise (preferably consists of) moieties III.Preferably, said polymeric material AA consistsessentially of repeat units which comprise (preferablyconsist of) moieties III.

Suitably, 60 mole%, preferably 80 mole%, more preferably90 mole%, especially substantially ail of said polymeric 12 material AA comprises vinyl moieties which are optionallycross-linked.

Preferably, the free bond to the oxygen atom in the -O-moiety pendent from the polymeric backbone of polymericmaterial AA (and preferably also in moieties II and III)is bonded to a group R10 (so that the moiety pendent fromthe polymeric backbone of polymeric material AA is offormula -O-R10) . Preferably group R10 comprises fewer than10, more preferably fewer than 5, especially 3 or fewercarbon atoms. It preferably only includes atoms selectedfrom carbon, hydrogen and oxygen atoms. R10 is preferablyselected from a hydrogen atom and an alkylcarbonyl,especially a methylcarbonyl group. Preferably moiety -O-R10 in said polymeric material AA is an hydroxyl oracetate group.

Said polymeric material , AA may include a plurality,preferably a multiplicity, of functional groups (whichincorporate the -0- moieties described) selected fromhydroxyl and acetate groups. Said polymeric material AApreferably includes a multiplicity of hydroxyl groupspendent from said polymeric backbone. Said polymericmaterial AA preferably includes a multiplicity of acetategroups pendent from the polymeric backbone.

Preferably, each free bond to the oxygen atoms in -0-moieties pendent from the polymeric backbone in polymericmaterial AA, except for any free bonds which are involvedin cross-linking the polymeric material AA, is of formula-O-R10 wherein each group -OR10 is selected from hydroxyland acetate. 13 1

Preferably, said polymeric material AA includes a vinylàlcohol moiety, especially a vinyl alcohol repeat unit.Said polymeric material AA preferably includes a vinylacetate moiety, especially a vinylacetate repeat unit.Polyvinylalcohol is generally made by hydrolysis ofpolyvinylacetate. Said polymeric material AA may comprisea 0-100% hydrolysed, preferably a 5 to 95% hydrolysed,more preferably a 50 to 90wt%, especially a 70 to 85wt%hydrolysed polyvinylacetate

Said polymeric material AA may hâve a number averagemolecular weight (Mn) of at least 10,000, preferably atleast 50,000, especially at least 75,000. Mn may be lessthan 500,000, preferably less than 400,000. Said polymericmaterial AA is preferably a polyvinyl polymer. Saidpolymeric material AA may be a copolymer.

Said polymeric material AA is preferably a polyvinylalcohol polymer or copolymer.

Preferably, said polymeric material AA includes at leastone vinyl alcohol/vinyl acetate copolymer which may includegreater than 5%, suitably includes greater than 30wt%,preferably greater than 65%, more preferably greater than80wt% of vinyl alcohol moieties.

Said polymeric material AA may be a random or blockcopolymer.

As described above, polymeric material AA is optionallycross-linked. A cross-linked material may be used in themethod when the Chemical or physical conditions to whichthe treatment fluid formulation may be subjected during theréduction in viscosity of the viscous composition and/or ί 14

during flow in a conduit means, for example in said firstconduit part (when provided) as described above, may berelatively harsh. In many applications, it is not benecessary to cross-link polymeric material AA. A cross-linked material as described is preferably ahydrogel. Such a hydrogel may be selected from a cross-linked natural or synthetic polysaccharide,polyvinylalcohol or polyvinylacetate.

When a. cross-linked material is used in the method, saidmethod preferably comprises selecting a said polymericmaterial AA; selecting a material BB which includes- afunctional group which is able to react in the presence ofsaid polymeric material AA to cross-link polymericmaterial TVA and form a polymeric material CC; and causingthe formation of said polymeric material CC by a reactioninvolving said polymeric material AA and material BB.

The ratio of the wt% of said material BB to the wt% ofsaid polymeric material AA selected for préparation ofsaid polymeric material CC is suitably less than 0.15,preferably less than 0.10, more preferably less than 0.05,especially less than 0.035. Said ratio may be at least0.005, preferably at least 0.01, more preferably at least0.015, especially at least 0.02.

The sum of the wt% of the polymeric material AA andmaterial BB selected for préparation of said polymericmaterial CC may be at least 0.4 wt%. The sum may be lessthan 5 wt%, preferably less than 4 wt%, more preferablyless than 3 wt%, especially less than 2.5 wt%. 1 3264 15

Suitably, the amounts of "polymeric material AA" and^material BB" described refer to the sum of the amounts ofpolymeric materials AA (if more than one type is provided)and the sum of the amounts of materials BB (if more thanone type is provided).

Preferably, formation of said polymeric material CC fromsaid polymeric material AA and material BB involves acondensation reaction. Preferably, formation of saidpolymeric material CC involves an acid catalysed reaction.Preferably, said polymeric material AA and material BBinclude functional groups which are arranged to react, forexample to undergo a condensation reaction, thereby - toform said polymeric material CC. Preferably, saidpolymeric material AA and material'BB include functionalgroups which are arranged to react for example to undergoan acid catalysted reaction thereby to form said polymericmaterial CC.

Said material BB may be an aldéhyde, carboxylic acid,urea, acroleine, isocyanate, vinyl sulphate or vinylchloride of a diacid or include any functional groupcapable of condensing with one or more groups on said polymeric material AA.include formaldéhyde,

Examples . of the aforementionedacetaldehyde, glyoxal andglutaraldehyde, as well as maleic acid, oxalic acid,dimethylurea, polyacroleines, diisocyanates, divinylsulphate and the chlorides of diacids.

Said material BB is preferably an aldéhyde containing orgenerating compound. Preferably, material BB is analdéhyde containing compound. 16

Material BB may include one or more aldéhyde groupe.Whilst it could be a monoaldehyde such as formaldéhyde itpreferably includes a plurality of aldéhyde groups. 5 Material BB may hâve a general formula

CHO

I

Gs

ίο I

CHO where G5 represents a direct link or a linking moiety. 15 G5 may be arranged to space apart the -CHO groups therebyto affect the spacing of the cross-linking of polymericmaterial AA.

In one embodiment, group G5 may be a -{CH2)y- moiety 20 wherein y represents 0 to 8, and one or more of the Hatoms may be replaced by (but preferably are not replacedby) another atom or group. Preferably, y represents 0 to6, more preferably 0 to 4, especially 0 to 2. 25 Group G5 may be arranged to introduce some rigidity intothe cross-linking of polymeric material AA. For example,group G5 may include at least some covalent bonds whichare not freely rotatable. For example, group G5preferably does not consist ex'clusively of a -CH2- chain 30 wherein each carbon-carbon bond will be freely rotatablebut preferably includes an atom or group or other meanswhich restricts free rotation compared to a case wherein 17

ΐ ο χ, tS A G5 consists of a -CH2- chain. For example G5 mayïncorporate bulky atoms or groups; and/or unsaturatedatoms or groups; and/or atoms or groups which hinder freerotation due to electronic effects.

Group Gs may include at least 1, preferably at least 2,more preferably at least 3, especially at least 4, carbonatoms in a chain extending between the two -CHO groups.

In one embodiment, group G5 incorporâtes one or morearomatic or heteroaromatic groups. Such groups may bearranged to restrict rotation as described. Preferredheteroaromatic groups include N-containing heteroaromaticgroups. Preferred aromatic and heteroaromatic groups areselected from optionally-substituted phenyl and N-containing aromatic groupe, such as pyridinyl groups.

Group G5 preferably includes both an aromatic and N-containing heteroaromatic group.

Group G5 preferably includes some charge séparation. Itpreferably includes a polar group. It preferably includesa cationic group. A preferred cationic group is one whichincludes a N+ moiety.

Group G5 may itself include one or more aldéhyde (orother) functional groups.

Said polymeric material CC may include a moiety 18

IV wherein the free bonds of the oxygen atoms are bonded tothe polymeric backbone and the free bond of the carbonatom is bonded to a residue of the material BB. Theresidue of material BB may also be bonded to the polymericbackbone of another polymeric chain (for example of apolymeric material AA as described), thereby to cross-linkpolymeric material AA.

Said material BB may comprise: (i) a first polymeric material having a repeat unit offormula wherein A and B are the same or different, are selectedfrom optionally-substituted aromatic and heteroaromaticgroups and at least one comprises a relatively polar atom or group and R1 and R2 independently comprise relatively non-polar atoms or groups; or (ii) a first polymeric material prepared or preparable byproviding a compound of general formula 19 1 3251 B1

R2 B wherein A, B, Rx and R2 are as described above, in anaqueous solvent and causing the groups C=C in said 5 compound to react with one another to form said firstpolymeric material.

In the first polymeric material described above, A and/orB could be multi-cyclic aromatic or heteroaromatic groups. 10 Preferably,. A and B are independently selected front. optionally-substituted five or more preferably six-membered aromatic and heteroaromatic groups. Preferredheteroatoms of said heteroaromatic groups include nitrogen, oxygen and sulphur atoms of which oxygen and 15 especially nitrogen, are preferred. Preferred heteroaromatic groups include only one heteroatom.Preferably, a or said heteroatom is positioned furthestaway from the position of attachment of the heteroaromaticgroup to the polymer backbone. For example, where the 20 heteroaromatic group comprises a six-membered ring, theheteroatom . is preferably provided at the 4-positionrelative to the position of the bond of the ring with thepolymeric backbone.

25 Preferably, A and B represent different groups.Preferably, one of A or B represents an optionally-substituted aromatic group and the other one represents anoptionally-substituted heteroaromatic group. Preferably Arepresents an optionally-substituted aromatic group and B 20 1 3264 représenta an optionally-substituted heteroaromatic groupèspecially one including a nitrogen heteroatom such as apyridinyl group.

Unless otherwise stated, optionally-substituted groupsdescribed herein, for example groups A and B, may besubstituted by halogen atoms, and optionally substitutedalkyl, acyl, acetal, hemiacetal, acetalalkyloxy,hemiacetalalkyloxy, nitro, cyano, alkoxy, hydroxy, amino,alkylamino, sulphinyl, alkylsulphinyl, sulphonyl,alkylsulphonyl, sulphonate, amido, alkylamido,alkylcarbonyl, alkoxycarbonyl, halocarbonyl and haloalkylgroups. Preferably, up to 3, more preferably up to 1optional substituents may be provided on an optionallysubstituted group.

Unless otherwise stated, an alkyl group may hâve up to 10,preferably up to 6, more preferably up to 4 carbon atoms,with methyl and ethyl groups being especially preferred.

Preferably, A and B each represent polar atoms or group -that is, there is preferably some charge séparation ingroups A and B and/or groups A and B do not include carbonand hydrogen atoms only.

Preferably, at least one of A or B includes a functionalgroup which can undergo a condensation reaction, forexample on reaction with said polymeric material AA.Preferably, A includes a said functional group which canundergo a condensation reaction.

Preferably, one of groups A and B includes an optionalsubstituent which includes a carbonyl or acetal group witha formyl group being especially preferred. The other oneof groups A and B may include an optional substituent whichis an alkyl group, with an optionally substituted, 21 preferably unsubstituted, Ci_4 alkyl group, for example a

Preferably, A represents a group, for example an aromaticgroup, especially a phenyl group, substituted (preferablyat the 4-position relative to polymeric backbone when Arepresents an optionally-substituted phenyl group) by aformyl group or a group of general formula

II where x is an integer from 1 to 6 and each R3 isindependently an alkyl or phenyl group or together form analkalene group.

Preferably, B represents an optionally-substitutedheteroaromatic group, especially a nitrogen-containingheteraromatic group, substituted on the heteroatom with ahydrogen atom or an alkyl or aralkyl group. Morepreferably, B represents a group of general formula R'

R

III X‘ 22

I

wherein R4 represents a hydrogen atom or an alkyl oraralkyl group, R5 represents a hydrogen atom or an alkylgroup and X' represents a strongly acidic ion. 5 Preferably, R1 and R2 are independently selected from ahydrogen atom or an optionally-substituted, preferablyunsubstituted, alkyl group. Preferably, R1 and R2 representthe same atom or group. Preferably, R1 and R2 represent ahydrogen atom. 10

Preferred first polymeric materials may be prepared fromany of the compounds described on page 3 line 8 to line 3 9of GB2030575B by the method described in WO98/12239 and thecontents of the aforementioned documents are incorporated 15 herein by reference.

Said first polymeric material may be of formula

20 wherein A, B, R1 and R2 are as described above and n is aninteger. Integer n is suitably 10 or less, preferably 8or less, more preferably 6 or less, especially 5 or less.Integer n is suitably at least 1, preferably at least 2, 25 more preferably at least 3.

Said polymeric material CC suitably includes a moiety offormula 23 1 3264

X

B wherein R1, R2 and B are as described above, A1 representsa residue of group A described above after the reactioninvolving said first polymeric material and polymericmaterial AA, Y represents a residue of said polymericmaterial AA after said reaction involving said firstpolymeric material and polymeric material AA and Xrepresents a linking atom or group extending between theresidues of said first polymeric material and saidpolymeric material AA. In one preferred embodiment A1represents an optionally-substituted phenyl group, Xrepresents a group

which is bonded via the oxygen atoms to a residue of saidpolymeric material AA. For example, group X may be bondedto the polymeric backbone of said polymeric material AA.

When said treatment fluid formulation comprises apolymeric material AA which is cross-linked, preferably,prior to the treatment fluid formulation çontacting theviscous composition, it has attained at least 70% of themaximum viscosity attainable for the formulation at thetempérature at which it is to contact the viscous 24 composition. Preferably, it bas attained at least 80%,more preferably 90%, especially about 100% of its maximumviscosity. Thus, in an especially preferred embodiment,said polymeric material AA and material BB are 5 ' substantially completely reacted to form said polymericmaterial CC prior to contact with said viscouscomposition.

After the viscous composition has been delivered to a10 desired location (for example a refinery) the viscouscomposition may be caused to separate from other components of the treatment fluid formulation. This maybe achieved by simply reducing any mixing or turbulentmovement of the mixture and allowing the viscous 15 composition to settle out from the water and optionallycross-linked polymeric material AA (which may besubstantially soluble in the water under the conditions ofsettling) . The rate of setting may be increased byincreasing the température of the viscous composition.

20 Additionally, the viscous composition may be diluted withlight oil or mechanical means may be used to encouragesettling. In some cases, for example, when said polymericmaterial AA is cross-linked, it may settle out asdescribed. In other cases, wherein polymeric material AA 25 is cross-linked, the method of the first aspect mayinclude the step of contacting the mixture with a breakermeans arranged to break an aqueous émulsion of the viscouscomposition. When polymeric material CC comprises 1,2-diol linkages, the breaker means is preferably arranged to 30 cleave 1,2-diol linkages. Said breaker means preferablycomprises a periodate (e.g. sodium or potassium periodate)in water. 25

The method of the first aspect preferably includes thestep of separating at least a part of the treatment fluidformulation from the viscous composition after the viscouscomposition has flowed along said fluid flow path. Afterséparation, said viscous composition suitably includesless than 10wt%, preferably less than 5wt%, especiallyless than 2wt% water. After séparation said viscouscomposition suitably includes less than 2wt%, preferablyless than 1 wt%, more prefefably less than 0.5wt%,especially less than 0.2wt%, of said optionally-cross-linked polymeric material AA.

When the method includes the separating step as described,the treatment fluid formulation which is separated fromthe viscous composition may be re-used to reduce theviscosity of further viscous composition. For example,the method may involve a continuous or semi-continuousprocess wherein treatment fluid formulation is contactedwith viscous composition to reduce its viscosity; themixture is then caused to flow downstream along a fluidflow path thereby to deliver the viscous composition to adesired location; the viscous composition and treatmentfluid formulation are separated; the viscous compositionis used and/or stored as required in said desiredlocation; the treatment fluid formulation is delivered toa location thereby to contact further viscous compositionupstream of said desired location; and the process issuitably repeated.

According to a second aspect of the présent inventionthere is provided a method of preparing a treatment fluidformulation (e.g. for reducing the viscosity of a viscouscomposition) comprising: 26

contacting an optionally cross-linked polymericmaterial AA as described according to the first aspectwith water.

Preferably, the polymeric material AA is dissolved in thewater thereby to préparé an aqueous solution of saidpolymeric material AA. Preferably, the polymeric materialAA is in the form of a solid prior to contact with water.

Preferably, at least 100 litres more preferably at least1000 litres of said treatment fluid formulation isprepared.

When the treatment fluid formulation is cross-linked, themethod may comprise: selecting a polymeric material AA(for example a polyvinylalcohol) and a material BB asdescribed according to said first aspect; and causing the formation of a said polymeric material CC by areaction involving said polymeric material AA and saidmaterial BB.

In the préparation of said polymeric material CC, acatalyst is preferably provided for catalysing thereaction of the polymeric material AA and said materialBB. Said catalyst is preferably a protic acid. Saidcatalyst is preferably phosphoric acid. Advantageously,when the fluid flow path of the first aspect is defined bySteel pipes the phosphoric acid may facilitate theformation of an anti-corrosive layer on the pipes. 27 1 3264

The method is preferably carried out adjacent or close toan oil field, for examples within 1 mile of a productionwell thereof. The method is preferably carried out within1 mile of an oil supply line which -is arranged to 5 transport oil between two locations.

According to a third aspect of the invention, there isprovided a treatment fluid formulation comprising: 10 - at least 95wt% water - . 4wt% or less of said polymeric material AA which hasoptionally been cross-linked as described above.

According to a fourth aspect of the invention, there is15- provided a method of reducing the viscosity of a viscouscomposition which is arranged to flow along a fluid flowpath, said method comprising contacting the viscouscomposition with a treatment fluid formulation, whereinsaid treatment fluid formulation includes a polymeric 20 material which: (a) is arranged to associate with, for example absorbonto, said viscous composition, especially oil, in orderto enable droplets of said viscous composition to be 25 formed, and/or.stablised; and/or (b) is arranged to form a coating (which may bediscontinuons) around droplets of said viscouscomposition; 30 (c) is arranged to form a hydrogel which is able tostabilise droplets of said viscous composition, especiallyoil. 28

Preferably, said polymeric material in said treatmentfluid formulation (which is preferably optionally cross-linked polymeric material AA described above) is arrangedto· form a material, for example a hydrogel which isarranged to associate with, for example coat, droplets ofsaid viscous composition, especially oil, in order toenable the formulation of a dispersion comprising saiddroplets.

Preferably, said polymeric material has each of theeffects described in (a) , (b) and (c) of the fourthaspect.

According to a fifth aspect of the invention, there isprovided a method of reducing the viscosity of a viscouscomposition which is arranged to flow along a fluid flowpath, said method comprising· contacting the viscouscomposition with a treatment fluid formulation whichincludes a hydrogel, for example of an optionally cross-linked polymeric material AA as described herein.

The invention extends to a réceptacle containing at least100 litres, preferably at least 200 litres, especially atleast 1000 litres of a said treatment fluid formulation asdescribed herein.

According to a sixth aspect of the invention, there isprovided a fluid flow path, for example a conduit means(preferably having a cross-sectional diameter at least inpart of at least 5cm and a length of at least 5m) whichcontains a fluid comprising petroleum, water and anoptionally cross-linked polymeric material AA as described 29 4¼ 'Μ ^as/ <£&. herein. Said polymeric material may be a hydrogel,preferably as described herein.

Any feature of any aspect of any. invention or embodimentdescribed herein may be combined with any feature of anyaspect of any other invention or embodiment describedherein mutatis mutandis.

Spécifie embodiments of the invention will now bedescribed, by way of example, with reference to figure 1which is a plot of viscosity vs. shear rate for variousformulations.

In general terms, heavy crude oil (and associatedmaterial) which may be too viscous to enable it to bepumped from the flowing face of a réservoir into and alonga pipeline, for example to a refinery or other storagefacility, may be contacted with a formulation at any pointwhere it is désirable to reduce the oil viscosity. In afirst embodiment, the formulation may comprise polyvinylalcohol which alone has been found to be capableadvantageously of reducing the viscosity of crude oilthereby enabling it to flow. In a second embodiment, theformulation may comprise a cross-linked polymericmaterial, for example cross-linked polyvinyl alcohol. Thematerial of the second embodiment may be more robustcompared to that of the first embodiment and may thereforebe used in more challenging situations.

After, the oil has been transported to a desired locationit may be separated from the other components in themixture by allowing it to settle; by increasing itstempérature; by dilution with light oil; by mechanical 30 séparation such as centrifugation (or the like) ; or bytreatment with a Chemical means such as a breaker which isarranged to break down cross-linked polymeric material.

Further details on the process are provided below.

Example 1 60g of an aqueous solution comprising 0.5% by weightpolyvinylalcohol (80-95% hydrolyzed) of molecular weight110,000 was added to a screw-capped glass vessel. Tothis was added 40g of a crude oil which had a viscositybetween 5800cP and 6500cP at a shear rate of 1 reciprocalsecond. The glass vessel was capped and the mixture wasagitated by ' hand-shaking for approximately 30 seconds.

The viscosity of the subséquent mixture was determinedto be between 1200cP and 1800cP at a shear rate of 1reciprocal second and less than 200cP at 100s'1.

Example 2

The procedure described in example 1 was followed with theexception that mixing was performed under high shear. Theviscosity of the final mixture was observed to be in therange 1200cP to 1800cP at a shear rate of 1 reciprocalsecond and less than 200cP at 100s’1.

Example 3 - Préparation of poly (1,4-di(4-(N- methylpyridinyl))-2,3-di(4-(1-formylphenyl)butylidene

This was prepared as described in Example 1 ofPCT/GB97/02529, the contents of which are incorporated 31

I 4 herein by reference. In the method, an aqueous solution ofgreater than 1 wt% of 4-(4-formylphenylethenyl)-l-methylpyridinium methosulphonate (SbQ) is prepared bymixing the SbQ with water at ambient température. Under 5 such conditions, the SbQ molécules form aggregates. Thesolution was then exposed to ultraviolet light. Thisrésulta in a photochemical reaction between the carbon-carbon double bonds of adjacent 4-(4-formylphenylethenyl)-1-methylpyridinium methosulphate molécules (I) in the 10 aggregate, producing a polymer, poly (1,4-di(4-(N-methylpyridinyl))-2,3-di(4-(1-formylphenyl)butylidenemethosulphonate (II).

Example 4 - Préparation of poly(vinylalcohol) solution 15 A 10wt% poly(vinylalcohol) solution was prepared by slowlystirring a known amount of water and adding a known amountof 88% hydrolysed poly(vinylalcohol) of molecular weight300,000 to the stirred water. The suspension was stirred 20 for 1 hour and, thereafter, the suspension was heated at atempérature of 60°C until the suspended particlesdissolved and the solution was clear. The solution wasthen allowed to cool to less than 5°C and maintained atthis température until used. 25

Example_5 _Préparation_of_butylidene polymer/poly(vinylalcohol) formulation 997.5g of the poly(vinylalcohol) solution prepared in 30 Example 4 and 2.5g of the butylidene polymer prepared inExample 3 were mixed together at ambient température togive a 10 wt% poly(vinylalcohol)/0,25wt% butylidenepolymer solution. This was diluted down to give a 2wt% 32 poly (vinyl alcohol)/0.05wt% butylidene polymer solution,ïhis solution was acidified to pH 1.5 with phosphoric acidand left to cure for 1 hour. After curing the solutionwas neutralised using 5M NaOH. This cured and neutralisedsolution was then further diluted to give a 1 wt%poly(vinylalcohol)/0.025wt% butylidene polymer solution;and a 0.05wt% polyvinylalcohol/0.0125wt% butylidenepolymer solutions.

On acidification of the polyvinylalcohol/butylidenepolymer blend as described, the two polymers react asdescribed in PCT/GB97/02529.

Example 6 - Protocol for préparation of oil émulsions

Emulsions of oil and the aqueous formulations of Example 5were prepared at ratios of oil: aqueous formulation of70:30 and 60:40 with the aqueous phase containing 2wt%,lwt% or 0.5wt% poly (vinylalcohol) . The oil and aqueousformulations were initially mixed using a spatula, thenhomogenized.

Example 7 - Protocol for évaluation of oil émulsions

The viscosity against shear rate of the émulsions wasmeasured on 0.65ml samples at 25°C taking 60 measuringpoints at 10 second întervals and a shear rate of 0.1 to1000s'1 followed immediately by a rate of 1000 to 0.1s'1.Results are provided in Figure 1 wherein:

33 * - Lines A and A1 are comparative examples detailing theresults for two runs undertaken without inclusion ofan aqueous formulation of Example 4. - Lines B and B1 are the results for two runs undertaken using the aqueous formulation of Example 5 with 2wt% poly(vinylalcohol). - Lines C and C1 are the results for two runs undertaken using the aqueous formulation of Example 5 with lwt% of poly(vinylalcohol). - Lines D and D1 are the results for two runs undertaken using the aqueous formulation of Example 5 with 0.5wt% of polyvinylalcohol.

Figure 1 shows that without the addition of anyformulation described in Example 5, the viscosity isrelatively high. When the formulation is added, there isa significant réduction in viscosity.

Thus, the formulation may be dosed into a oil flow at anypoint at which it is desired to reduce the oil's viscosityto enable it to be transported. For example, it may beclosed in at the bottom of a riser pipe to reduce theviscosity of oil flowing upwardly in the pipe.Alternatively, it may be closed in at or near the surface.Once closed in, the oil may be transported long distancesthrough a pipeline to a refinery or other oil storagefacility.

After completion of the transport stage, it is necessaryto recover the oil from the émulsion. This may beachieved by allowing the mixture to settle; by mechanicalmeans or by Chemical means. An example of the latter mayinvolve the addition of 0.1 to 0.3wt% (preferably about 34 0.2 wt%) of a periodate sait (preferably the sodium sait)to the émulsion. This causes the destruction of theémulsion and enables the oil to be recovered for furtherProcessing.

Bxample_ 8_- ~_Préparation__of glutaraldehyde/poly(vinylalcohol) formulation A poly(vinylalcohol) solution of a 88% hydrolysedpoly(vinylalcohol) having a molecular weight of about160,000 is prepared by dissolving 87g of thepoly(vinylalcohol) in 1000ml of water by stirring thecomponents for 24 hours at 80-90°C. The solution is thenallowed to cool to 50°C and 1.29 ml of a 25% solution ofglutaraldehyde added with stirring for about 1 'hour.Then, 10 0ml of IM HCl is added with stirring and a gelforms which may be used as described above.

Example 9 - Préparation of glyoxal/poly(vinylalcohol) formulation

By a process analogous to Example 8 a glyoxal cross-linkedpoly(vinylalcohol) may be prepared.

The materials of Examples 8 and 9 may be used in viscosityréduction as described herein.

Attention is directed to ail papers and documents whichare filed concurrently with or previous to thisspécification in connection with this application andwhich are open to public inspection with thisspécification, and the contents of ail such papers anddocuments are incorporated herein by reference.

35 Λ U £- Àll of the features disclosed in this spécification(including any accompanying daims, abstract anddrawings) , and/or ail of the steps of any method or 5 process so disclosed, may be combined in any combination,except combinations where at least sonie of such featuresand/or steps are mutually exclusive.

Each feature disclosed in this spécification (including10 any accompanying daims, abstract and drawings) may berepla.ced by alternative features serving the same,équivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, eachfeature disclosed is one example only of a generic sériés 15 of équivalent or similar features.

The invention is not restricted to the details of theforegoing embodiment(s) . The invention extends to anynovel one, or any novel combination, of the features 20 disclosed in this spécification (including anyaccompanying daims, abstract and drawings) , or to anynovel one, or any novel combination, of the steps of anymethod or process so disclosed.

Claims

1. A method for reducing the viscosity of a viscouscomposition which is arranged to flow along a fluid flowpath, said method comprising contacting the viscouscomposition with a treatment fluid formulation, saidtreatment fluid formulation comprising a polymericmaterial AA which includes -0- moieties pendent from apolymeric backbone thereof, wherein polymeric material AAis optionally cross-linked.

2. A method according to claim 1, wherein the viscosityof the viscous composition after contact with thetreatment fluid formulation is less than 3 0 0cP measured at25°C and 1000s'1.

3. A method according to claim 1 or claim 2, wherein theviscous composition, after contact with the treatmentfluid formulation, exhibits shear thinning.

4. A method according to any preceding claim, whereinsaid viscous composition is an oil.

5. A method according to any preceding claim, whereinsaid treatment fluid formulation is initially contactedwith said viscous composition at or downstream of aproduction means.

6. A method according to claim 5, wherein said fluid flowpath is defined by a conduit means which includes a firstconduit part which is arranged downstream of a production means.

37

7. A method according to any preceding claim, whereinsaid fluid flow path extends between a first point, remotefrom the point of production of the viscous composition,and a second point doser to the point of production ofthe viscous composition.

8. A method according to any preceding claim, wherein said fluid flow path is defined, in part, by a second conduit part which extends upwardly from below ground to above ground.

9. A method according to any preceding claim, wherein said treatment fluid formulation is arranged to disperse and/or emulsify said viscous composition, on contact therewith.

10. A method according to any preceding claim, wherein flow is turbulent at the point of initial contact of said viscous composition with said treatment fluid formulation so that said composition is dispersed and/or emulsified on contact with said formulation.

11. A method according any preceding claim, wherein a delivery flow path is defined which is arranged to communicate with said fluid flow path wherein said treatment fluid formulation is dosed into said viscous composition in said fluid flow path via said delivery flow path. ' 4

12. A method according to any preceding claim, wherein the ratio of the flow rate (in weight per unit time) of treatment fluid formulation in said delivery flow path to 38 the flow rate (in the same units) of viscous compositionin said fluid flow path is in the range 0.1 to 2.5.

13. A method according to any preceding claim, wherein theamount of water in the composition in said fluid flow pathimmediately after contact between said viscous compositionand said treatment fluid formulation is less than 70wt%.

14. A method according to any preceding claim, whereinsaid treatment fluid formulation has a viscosity at 25 °Cand 1000s'1 of greater than lcP and not greater than 50cP.

15 wherein A and B are the same or different, are selectedfrom optionally-substituted aromatic and heteroaromaticgroups and at least one comprises a relatively polar atomor group and R1 and R2 independently comprise relatively 20 non-polar atoms or groups; or (ii) a first polymeric material prepared or preparable byproviding a compound of general formula 1 3264 43

B wherein A, B, R1 and R2 are as described above, in anaqueous solvent and causing the groups C=C in said 5 compound to react with one another to form said firstpolymeric material.

15. A method according to any preceding claim, whereinsaid treatment fluid formulation includes at least 70wt%water.

16. A method according to any preceding claim, whereinsaid treatment fluid formulation includes at least 0.2wt%and less than 10wt% of said polymeric material AA.

17. A method according to any preceding claim, whereinsaid treatment fluid formulation includes 94.5 to 99.6wt%water and 0.4 to 5.5wt% of said polymeric material AA; andthe ratio of the wt% of said treatment fluid formulationto the wt% of said viscous composition contacted in themethod is in the range 0.4 to 0.9.

18. A method according to any preceding claim, whereinsaid polymeric material AA is wholly soluble in water at 25°C. 39 (> 1 % f K**

19. A method according to any preceding claim, whereinsaid polymeric backbone of said polymeric material AAin.clu.des carbon atoms which are part of -CH2- moieties.

20. A method according to any preceding claim, whereinsaid polymeric backbone consists essentially of carbonatoms in the form of C-C single bonds.

21. A method according to any preceding claim, whereinsaid treatment fluid formulation irtcludes a hydrogel whichis an optionally cross-linked polysaccharide,polyvinylalcohol or polyvinylacetate.

22. A method according to any preceding claim, whereinsaid -0- moieties are directly bonded to the polymericbackbone.

23. A method according to any preceding claim, whereinsaid polymeric material AA includes, on average, at least10 -0- moieties pendent from the polymeric backbonethereof.

24. A method according to any preceding claim, whereinsaid polymeric material AA includes a moiety: G3 I g<_C--G2 II 40 13264 where G1 and G2 are other parts of the polymeric backboneand G3 is another moiety pendent from the polymericbackbone. 5

25. A method according to any preceding daim, wherein at least 60 mole% of the polymeric material AA comprisesvinyl moieties which are optionally cross-linked.

26. A method according to any preceding claim, wherein10 the free bond to the oxygen atom in the -O- moiety pendent from the polymeric backbone of polymeric material AA isbonded to a group R10 which comprises fewer than 10 carbonatoms and only includes atoms selected from carbon,·hydrogen and oxygen atoms. 15

27. A method according to claim 26, wherein moiety -O-R10 in said polymeric material AA is an hydroxyl oracetate group. 20

28. A method according to any preceding claim, which involves selecting a said polymeric material AA; selectinga material BB which includes a functional group which isable to react in the presence of said polymeric materialAA to cross-link polymeric material AA and form a 25 polymeric material CC; and causing the formation of saidpolymeric material CC by a réaction involving saidpolymeric material AA and material BB.

29. A method according to claim 28, wherein formation of 30 said polymeric material CC from said polymeric material AAand material BB involves a condensation reaction. 41 1 3264

30. A method according to daim 28 or daim 29, whereinsaid material BB is selected from an aldéhyde, carboxylicacid, urea, acroleine, isocyanate, vinyl sulphate or vinylchloride of a diacid or includes any functional groupcapable of condensing with one or more groups of saidpolymeric material AA.

31. A method according to any of daims 28 to 30, whereinmaterial BB has a general formula: CHO I Gs I CHO where Gs représente a direct link or a linking moiety.

32. A method according to claim 31, wherein group G5 isarranged to introduce rigidity into the cross-linking ofpolymeric material AA, wherein group G5 includes at leastsome covalent bonds which are not freely rotatable.

33. A method according to claim 31 or claim 32, whereingroup G5 incorporâtes one or more aromatic orheteroaromatic groups.

34. A method according to any of daims 31 to 33, wherein group G5 includes a polar group.

35. A method according to any of daims 2 8 to 34, wherein said polymeric material CC includes a moiety pmi 42 \ oZXCH IV wherein the free bonds of the oxygen atoms are bonded to5 the polymeric backbone and the free bond of the carbon atom is bonded to a residue of the material BB.

36. A method according to any of daims 2 8 to 35,wherein said material BB comprises: 10 (i) a first polymeric material having a repeat unit offormula

36 CLAIMS

37. A méthod according to claim 36, wherein said firstpolymeric material is of formula 10 wherein n is an integer. 15

38. A method according to any preceding claim, wherein after the viscous composition has been delivered to adesired location the viscous composition is caused toseparate from other components of the treatment fluidformulation.

39. A method according to claim 38, wherein séparationis achieved by reducing mixing or turbulent movement ofthe mixture and allowing the viscous composition to settleout from the water and optionally cross-linked polymeric 25 material AA. 20 44

40. A method of préparation a treatment fluid formulationcomprising contacting an optionally cross-linked polymericmaterial AA as described in any preceding claim, withwater. 5

41. A treatment fluid formulation comprising: - at least 95wt% water - 4wt% or less of said polymeric material AA which has 10 optionally been cross-linked.

42. A method of reducing the viscosity of a viscouscomposition which is arranged to flow along a fluid flowpath, said method comprising contacting the viscous 15 composition with a treatment fluid 'formulation, whereinsaid treatment fluid formulation includes a polymericmaterial which: (a) is arranged to associate with, for example absorb 20 onto, said viscous composition, especially oil, in order to enable droplets of said viscous composition to beformed and/or stablised; and/or (b) is arranged to form a coating (which may be 25 discontinuous) around droplets of said viscous composition; (c) is arranged to form a hydrogel which is able tostabilise droplets of said viscous composition, especially 30 oil. 1 3264 45

43. A réceptacle containing at least 100 litres oftreatment fluid formulation as described in any of a saiddaims 1 to 41.