AU613925B2 - Scale inhibition - Google Patents

Description

I

P159625 JGS:GS 3617T/2

AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE 411 Ii 7 7 Application Number: Lodged: Complete Specification Lodged: Accepted: Published: :Priority: 'Related Art: 4 A~ V TO BE COMPLETED BY APPLICANT *:"*Name of Applicant: Address of Applicant: 'tual Inventor: Address for Service: 9 CIBA-GEIGY AG Klybeckstr'sse 141, 4002 Basle, Switzerland Dr. Barry Cook ARTHUR S. CAVE CO.

Patent Trade Mark Attorneys Level Barrack Street SYDNEY N.S.W. 2000

AUSTRALIA

.~Complete Specification for the invention entitled SCALE

INHIBITION,

The following statement is a full description of this invention including the best method of performing it known to me:- 1 ASC 49

X

la- 3-16519/1+2/=/MA 1904 Scale Inhibition The present invention relates to scale inhibition and, in particular, to a method of inhibiting barium scale deposition from waters of high bariur content e.g. deeper formation waters.

Deeper formation water, e.g. those found in the North Sea, have lower pH values of about 3 to 7 and a higher barium content than f" tion waters which are closer to the earth's surface.

In the subsea secondary recovery by water flooding, a great deal of water S is required and recourse may be needed to such deepet formation waters S for mixing with sea-water derived from upper sea regions. Such mixing of 9 9 i ncompatible waters can lead to severe barium sulfate scaling problems in well bore production equipment and conventional anti-scalants e.g.

polyacrylates are not effective against this particular scale.

S From the GB-A 2 152 919 a method became known, to treat scale in pressurised boiler water systems with a copolymer of maleic or fumaric acid and vitnl sulfonic or allyl sulfonic acid., There is no mention of the barium scale from waters of high barium content and the method is restricted to pressurised boiler systems.

Another reference, GB-A 2 105 319, describes a treatment of aqueous systems by a composition comprising an aminocarboxylate and a copolymer of mal Lc acid and styrene sulfonic acid. The composition relies upon the essential use, as co-inhibitor, of amino-carboxylate compound.

2 In I.E. Woerner and R.A. Holzer, Proc. Int. Water Conf. Eng. Soc. West Pa pages 281-287, volume 42, an experimental sulfonated polymer was found suitable as an inhibitor for BaSOil-scale. However, no indication of the precise structure of the sulfonated polymer in question could be found.

R.W. Mitchell, D.M. Grist and M.J. Boyle in Journal of Petroleum Technology, pages 904-912, volume 32, number 5, simply describe polymeric scale inhibitors (A and B) and organic phosphonates (C and E) as barium sulfate inhibitors and the effect of adding barium sulfate inhibitors to d* the seawater. Also, no pre' se structure of the polymer in question could be found.

a We have now found that certain water-soluble vinyl sulfonate homo- or copolymers provide excellent barium scale inhibition in waters having a G" high barium content.

Accordingly, the present invention provides a method of inhibiting barium sulfate scale deposition from water of high barium content, comprising adding to the water an effective amount of a water-soluble polymer, or salts thereof, containing m units of a moiety A, n units of a moiety B and p units of a moiety D, wherein A is a moiety having the formula I 4 4(I) 03M 3 in which RI, 12 and R 3 independently, are hydrogen, CO0M, Ci-C 4 alkyl or phenyl, but preferably Ri, R 2 and R 3 are each hydrogen; and M is hydrogen, an alkali- or alkaline earth metal, ammonium or an amine residue; B is a moiety having the formula II

(II)

3in which R4 and R 5 indepenidently, are hydrogen, phenyl, Cl-Ci~alkyl (optionally substituted by an hydroxyl group or a carboxyl group, or interrupted by an oxygen atom or a carbonyl group), SO 3 H, halogen, hydroxyl or CI-Ci~alkoxy, Ri, and R 5 preferably each being hydrogen; X. is hydrogen or -CO 2 M wherein M has its previous significance; and Y -00214 wherein M has its previous significance or X and Y together may focm an anhydride group; and D is a moiety different from B and having the formula III 6 wherin 6 ishydogenmnithyl or a residue -COORB in which R 8 is hydrogen or Gi-Cz~alkyl group; R 7 is hydrogen, Cl-C~alkyl, hydroxynethyl or -rOOR 9 in which Rq is hydrogen, a residue of formula IV 0

(IV)

-CH 2 C If G 2 or R 9 is a straight or branched chain alkyl having 1 to 4 carbon atoms or CI-Cilalkyl substituted by -S0 3 14 or by -COON where M has its previous significance; Z is -COOR 9 where R 9 is as defined above, or Z is a straight or branched alklil having 1 to 4 carbon atoms or said alkyl substituted by one to three carboxylic acid groups; or Z is phenyl or said phenyl substituted by -S03M or by -PO.

3 11 2 or Z is acetoxy, hydroxy, hydro,,ymethyl, acetoxymethyl, -C[1 2 S0i, -CI 2 POiA2, -P0 3

M

2 or -PO 3 in which 'M has its previous significance and M' is M or alkyl of 1 to 4 carhon atoms; or 7 is a residue -CONRijR1 2 wherein R 1 1 and R 1 2 are the same or diffcrent and each is hydrogen, straight or branched chain alkyl having I to 4 carbon atoms, hydroxymethyl -CUH(OFI)COOM, -C(CH 3 aC't12SO3M, C~i j)',!CllPOjM2 or -N(Ri 3 )CO'13 In Which R13~ is hydrogen or straight or branched chain alkyl 'r o e r

I

4 of 1 to 4 carbon atoms and M has its previous significance; m is an integer, n is 0 or an integer and p is 0 or an integer.

Preferably the values of m, n and p being such that the molecular weight of the polymer ranges from 500 to 10,000 while retaining its water solubility.

Preferred ratios of moieties A, B and D in the polymer are determined by the preferred requirements that A constitutes 100 to 10 of the total polymer; B constitutes 0 to 90 of the total polymer; and D constitutes 0 to 25 of the total polymer, each by weight on total polymer.

Salts of the polymers used in the method of the invention are products in Swhich some or all of the acidic hydrogens in acidic polymers have been replaced by alkali metal ions, ammonium ions or quaternised amine radicals. These salts also have good activity in inhibiting barium sulfate scale deposition.

C]-Cialkyl residues RI, Ra, R3, R4, Rs, R7, RO, R 9 R11, R 1 2, R 1 3 or Z are e.g. methyl, ethyl, n-propyl, isopropyl or n-butyl residues.

Cacboxyl-substituted Ci-Cialkyl residues Z include carboxymethyl, carboxyethyl, carboxypropyl, 1,1-dicarboxymethyl and 2,3,4-tricarboxybutyl residues.

Alkali metal atoms M or M' are, particularly, sodium or potassium atoms; alkaline earth metal atoms M or M' are, preferably calcium, barium or strontium atoms; and amine residues M or M' are, especially, -NH(CH3) 3

-NH(C

2 Hs) 3 or -NH(CHaCH 2

OH)

3 The polymers used in the method of the present invention may be produced by reacting m moles of C(RI)(R 2

)=C(R

3 )S03H with n moles of and p moles of CH(R,)=C(R 7 )Z wherein RI, R 2

R

3

R

4 Rs, RG, R 7 X, Y, Z, m, n and p have their previous significance, under conventional free radical-initiated polymerisation processes. Depending

_.A

upon the solubility of the respective monomer or monuiners, the polymerisation is carried out in an aqueous or partially aqueous solution, for instance water/lower alkanol solution, lower alkanols such as isopropanol, or hydrocarbon solvents e.g. toluene or xylene. Conventional free radical initiators which may be used include peroxides e.g. hydrogen peroxide, benzoyl peroxide, acetyl peroxide, di t-butyl peroxide, t-butylhydroperoxide; perdicarbonates; persulfates; azobis-isobutyronitrile; and the so-called redox and heavy metal polymerisation initiators. The polymerisation procedure may also include the use of telogens, or chain-transfer agents e.g. alcohols, mercaptans, hypophosphorous acid or orthophosphorous acids or their salts to control th molecular weight of the polymer product.

S.

V Examples of comonomers of formula C(R 1

)(R

2

)=C(R

3 )SO3H include vinyl sulfonic acid, -styrenesulfonic acid, 1-propene sulfonic acid, 2-propene sulfonic acid, sulfomaleic acid and their salts and preferably vinyl sulfonic acid and their sodium salts.

S.

SComonomers of formula C(R4)(X)=C(R 5 )Y include acrylic acid and methacrylic acid, maleic acid or anhydride and fumaric acid.

Comonomers CH(R 5

)=C(R

7 )Z include acrylamide, N-hydroxymethylacrylamide, N,N-dimethylacrylamide, N-vinyl-N-methylacetamide, N-allylacetamide, N-acrylamidoglycollic acid, methacrylic acid, methyl methacrylate, fumaric acid, maleic acid, maleic anhydride, 2-carboxyethyl acrylate, 3-buten-1,2,3-tricarboxylic acid, dimethyl maleate, diethyl maleate, diethyl fumarate, itaconic acid, dimethyl itaconate, allyl sulfonic acid, 4-styrene sulfonic acid, sodium- or potassium salts of 3-sulfopropyl acrylic acid, 2-acrylamido-2-methyl-propane sulfonic acid, vinyl phosphonic acid, styrene phosphonic acid, allyl alcohol, allyl acetate, vinyl acetate, styrene, a-methyl styrene, hcxene, octene, N-acrylamidopropane sulfonic acid, glycidyl methacrylate, crotonic acid, ethyl crotonate, polyethylene glycol esters and polypropylene glycol esters of (meth)acrylic acids.

6- Alternatively, a salt of the comonomer may be employed in which the acidic hydrogens have been partially or completely replaced by cations M or M' derived from a suitable salt forming base.

The products of the polymerisation process are obtained as solutions.

These may be subjected to partial or complete evaporation under reduced pressure. The unpurified reaction products may be used as the polymeric products in the method of the invention. The reaction products may be purified if desired. The purification procedure may be: i) by evaporation of reaction solvent, dissolving the residue in water, washing with a water-immiscible organic solvent e.g. ether and evaporation of the aqueous solution.

ii) by evaporation of reaction solvent, dissolving the residue in methanol and reprecipitation by addition of ether.

When the reaction products are employed without purification, the ratio a.

of reactants is important in that the activity of the product varies accordingly.

Salts of the polymers used according to the invention in which some or all of the acidic hydrogens in the polymer having been replaced by the cations derived from a suitable salt forming base, may be prepared by mixing an aqueous or alcoholic solution of the polymer with an aqueous or alcoholic solution containing an amount of the requisite base in excess of, equal to or less than the stoichiometric requirement. The solvent may then be removed by evaporation.

The polymer is preferably added to the water to be inhibited against barium sulfate scale deposition in an amount ranging from 1 to 200 ppm especially from 1 to 30 ppm, based on the weight of the water to be treated.

7 The polymer scale inhibitor used according to the invention may be used alone or in conjunction with other compounds known to be useful in the treatment of aqueous systems, e.g. corrosion inhibitors; dispersing and/or threshold agents; precipitating agents; oxygen scavengers; sequescering agents; antifoaming agents; biocides; and demulsifiers.

Corrosion inhibitor co-additives include for example, water soluble zinc salts; phosphates; polyphosphates; phosphonic acids and their salts, for example, hydroxyethyl-diphosphonic acid (HEDP) nitrilotris methylene phosphonic acid and methylamino dimethylene phsophonoacarboxylic acids an" their salts, for example, those described in German Offenlegungsschrift 2632774, hydroxyphosphonoacetic acid, 2-phosphonobutane-l,2,4tricarboxylic acid and those disclosed in GB 1572406; nitrates, for example sodium nitrate; nitrites e.g. sodium nitrite; molybdates e.g sodium molybdate; tungstates; silicates e.g. sodium silicate; benzotriazole, bis-benzotriazole or copper deactivating benzotriazole or tolutriazole derivatives or their Mannich base derivatives; mercaptobenzothiazol; N-acyl sarcosines; N-acylimino diacetic acids; ethanolamines; fatty amines; and polycarboxylic acids, for example, polymaleic acid and polyacrylic acid, as well as their respective alkali metal salts, copolymers of maleic anhydride, e.g. copolymers of maleic anhydride and sulfonated styrene, copoylmers of acrylic acid e.g.

copolymers of acrylic acid and hydroxyalkylated acrylic acid, and substituted derivatives of polymaleic and polyacrylic acids and their opolymers. MoreQ in such completely aqueous systems, the corrosion inhibitor used according to the invention may be used in conjunction with dispersing and/or threshold agents e.g. polymerised acrylic acid (or its salts), phosphino-polycarboxylic acids (as described and claimed in British Patent 1458235), the cotelomeric compounds described in European Patent Application No. 0150706, hydrolysed polyacrylonitrile, polymerised methacrylic acid and its salts, polyacrylamide and co-polymers thereof from acrylic and methacrylic acids, lignin sulphonic acid and its salts, tannin, naphthalene sulphonic acid/formaldehyde condensation products, starch and its derivatives, cellulose, acrylic acid/lower alkyl hydroxyacrylate copolymers e.g. those described in U.S. Patent Specification No. 4029577, styrene/maleic anhydride copolymers and sulfonated styrene homopolymers e.g. those described in U.S. Patent Specification No. 4374733 and combinations thereof. Specific threshold agents, such as for example, 2 -phosphonobutane-l,2,4-tri-carboxylic acid (PBSAM), hydroxyethyldiphosphonic acid (HEDP) hydrolysed polymaleic anhydride and its salts, alkyl phosphonic acid, hydroxyphosphonoacetic acid 1-aminoalkyl-1, 1-diphosphonic acids and their salts, and alkali metal polyphosphates, may also be used.

Particularly interesting additive packages are those comprising rompounds of formula I with one or more of polymaleic acid or polyacrylic acid or S their copolymers. or substituted co-polymers, HEDP, PBSAM, triazoles such S as tolutriazole, molybdates and nitrites.

Precipitating agents used may be aikali metal orthophosphates or -carbonates.

*o Oxygen scavengers include alkali metal sulfites and hydrazines; sequestering agents may be nitrilotriacetic acid and its salts; antifoaming agents such as silicones, e.g. polydimethylsiloxanes, distearylsebacamide, distearyl adipamide and related products derived from ethylene e5 oxide and/or propylene oxide condensations, in addition to fatty alcohols, such as capryl alcohols and their ethylene oxide condensates; biocides include, e.g. amines, quaternary ammonium compounds, chlorophenols, sulfur-containilg compounds such as sulfones, methylene bis thiocyanates and carbamates, acrolein, isothiazolones, brominated propionamides, triazines, phosphonium compounds, glutaraldehyde, chlorine and chlorine-release agents and organo-metallic compounds such as tributyl tin oxide, and demulsifiers include alkyl phenol resin ethoxylates derived from butyl-, amyl-, octyl- and nonyl-phenols, ethylene oxide-propylene oxide block copolymers, polyalkylene oxide esters of mono- and polycarboxylic acids, alkoxylated alkyl amines, alkoxylated polyamines, sulfonated systems, polvsiloxane derivatives and cationic polyacrylamides.

The following Examples further illustrate the present invention.

-I r: 9 Example 1: Vinyl Sulf, :ic Acid/Acrylic acid copolymer (molar ratio 1:3) A solution of 54 parts by weight. of acrylic acid, 1-0 parts by weight sodium vinyl sulfonate (as a 25 aqueous solution), and 5.5 parts by weight of sodium hypophosphite in 150 parts by weight of water, is prepared and is designated solution 1. A further solution of 1.5 parts by weight of sodium periulfate in 100 parts by weight of water is prepared and designated solution 2. The two solutions (solution 1 and solution 2) are added synchronously, over 2 hours, to a reaction vessel containing parts by weight of water at the reflux temperature (100OC). The reflux temperature is maintained for a further 1 hour to give 500.8 parts by weight of polymer solution having a solids content of 2U.85 HPLC analysis shows the solution to contain only trace amounts (at most 0.5 of unreacteC monomes.

Example 2: Vinyl Sulfonic Acid/Maleic Acid Copolymer (Molar ratio 1:1) A solution of maleic acid mono sodium salt is prepared by the addition of parts by weight of sodium hydroxide to a mixture of 49 parts by weight of maleic anhydride in 50 parts by weight of water. To this, is added 216,6 parts by weight of sodium vinyl sulfonate (as a 30 aqueous solution) and the resulting solution is heated to the reflux temperature (1000C). A further solution of 5.95 parts by weight of sodium persulfate in 32.1 parts by weight of hydrogen peroxide (30 w/v) is added, dropwise, over 4 hours at 100°C and the heating further continued for 2 hours, to give 346 parts by weight of a polymer solution having a Ssolids content of 43 HPLC :nalysis showed less than 1 unreacted 9 monomer.

Examples 3 and 4: Barium Sulfate Threshold Test A volume (50 ml) of a sodium sulfate solution is added to an equal volume of a solution containing barium chloride and sodium chloride and which already contains the additive under test. After addition of an acetic acid/sodium acetate buffer to buffer the pH at 5.5, the resultant solution is stored at 25°C for 24 hours, and then filtered.

At the end of this time the barium remaining in solution is determined by Atomic Absorption The results are expr,: c as inhibition of barium sulfate precipitation.

FL Reagents 1) Solution 1 0.3518 g/l BaCln.2H 2 0 quality) and 40.00 g NaCI quality). (This gives 98.9 ppm as Ba+ and 20,000 ppm of NaC1 in final 100 ml test solution).

2) Solution 2 0.800 g/l Na 2 SOQ. (This gives 270.5 ppm as SOi, in final 100 ml test solution).

3) Solution 3 Molar acetic acid solution 6.0 g glacial acetic acid quality) are dissolved in distilled water and made up to 100 ml.

4) Solution 4 Molar sodium acetate solution 13.61 g CH 3 COONa, 3H 2 0 quality) are dissolved in distilled water and made up to 100 ml.

S 5) Solution 5 0.1 solids additive solutions the appropriate weight of additive is dissolved in distilled water and adjusted to pH 5.5 with HC1 solution or NaOH solution, and made up to 100 ml.

Procedure A constant temperature water bath is set at 35 0 C. 50 ml of solution (1) is placed in a clean, new 4 ounce (113.4 g) glass bottle. 0.10 ml of solution and 1.00 ml of solution are added using a micro-pipette.

0.60 ml (6 ppm) of the additive solution (solution is added using a micro-pipette. 50 ml of solution is then added. The screw cap is placed on the bottle and the reagents are mixed. The bottle is placed in the constant temperature water bath at 25 C for 4 hours without agitation. 50 ml of the liquor is filtered through a 0.45 micron mesh filter into a 4 ounce (113.4 g) glass bottle using a 50 ml plastic syringe.

ml of the liquor is immediately pipetted into a standard 100 ml volumetric flask and diluted to the mark with distilled water. The Ba++ concentration of this 4olution is then determined by Atomic Absorption

(AA).

All tests are done in duplicate, including blank tests (no additive).

I

11 Additionally, for the purpose of AA measurement, a matrix solution minus Ba+ is required to standardise the instrument.

The matrix solution is prepared by dissolving 2 g Nar ml distilled water in a 4 ounce (113.4 g) glass L quality) in 0 ml of solution are added. The reagents are mixed and 50 ml of the mixture pipetted into a 250 ml standard volumetric flask. 150 ml of distilled water are added, without making up to the mark.

Calculation Before calculating I, the AA ppm Ba readings should be multiplied by the dilution faction x 9.9, 9 9 90 a (ppm Ba++ ppm Ba (blank)) 98.9 ppm Ba+ (blank) 100 1 I percentage of inhibition of barium sulfate prucipitation. The results are set out in Tabie 1.

Table I 4.

'4 9 4 9 e 999 4

QS

.n 90 .g 99 9 9 4 99 Example Test Compound inhibition to precipitation at dose level 6 ppm 3 Prod. Ex. 1 87 4 Prod. Ex. 2 92 In further demonstration of the efficacy of the method of the present invention, we now refer to the following Test Report wherein methods o; inhibiting barium sulfate scale deposition from water of high barium content, using water soluble polymer as proposed in this application and the preferred compound utilized in the prior art (EP 184894), are compared. The vastly superior results achieved by the method of the present invention are clearly evident.

I I i I 12 Test Report I Preoaration of the products to be tested as additives to water to control BaS04 scale a) A solution (solution 1) of 64.8 g of acrylic acid, 11.7 g of sodium vinyl sulphonate (as a 30 aqueous solution) and 2.75 g of sodium hypophosphite in 25 g of water is prepared. A further solutiun (solution 2) is prepared of 0.74 g of sodium persulphate in 25 g of water. Solutions 1 and 2 are added, synchronously, over 2 hours to a reaction vessel containig 25 g of water, at the reflux temperature (100 0 The reflux temperature is maintained for a further 2 hours to give 178 g of a pale yellow acrylic/vinyl sulphonic copolymer solution having a solids content of 49.1 HPLC analysis shows that the solution contains less than 0.5 by weight of unreacted monomers.

S b) The procedure set out under supra, is repeated except that 32.4 g of acrylic acid and 10.3 g of acrylamidomethyl propane sulphonic acid. sodium salt, (AMPS) are reacted to produce a pale yellow copolymer solution (II) having a solids content of approximately 40 and containing less than 0.5 of unreacted monomers.

II Evaluation of polymer solutions I* and II as barium sulphate scale control agents Equal volumes of natural sea water and synthetic formation water are mixed, together with the additi under test, and shaken at 70°C for 3 hours, the pH of the mixture being maintained at over 3 hour period, by the addition of sodium acetate/acetic acid buffer.

*P

A standard solution, namely the natural sea water and the synthetic formation water, containing no test additive; and a blank solution, namely synthetic formation water plus synthetic sea water containing no sulphate, are run at the same time.

At the end of the test, the respective solutions are filtered and 15 .l of each filtrate is diluted to 100 ml with distilled water. Each resultant diluted solution is analysed for barium by atomic absorption.

The percentage barium sulphate inhibition is calculated from the following equation: BaSO 4 barium in test solution barium in blank S100 inhibtion barium in standart solutien barium in blank

WE-

13 The results are shown in the following Table: Test BaSO 4 inhibition Compound at 10 ppm dose level 1* 93 11 34 The results clearly show that an acrylic/vinyl suiphonic copolymer according to the present invention provides vastly and une xpectedly superior barium sulphate inhibition relative to a acrylic acid/AMIPS copolymer.

fleE

C.

C.

C **CR

C

S

C

0 *0

S

C

S3 S S. S *5

Claims (2)

14- The claims defining the invention are as follows:- 1. A method jf inhibiting barium sulfatc scale deposition from water of high barium content, comprising adding to the water an effective amount of a water-soluble plymer, or salts thereof, containing m units of a moiety A, n units of a moiety B and p units of a moiety D, wherein A is derived a moiety having the formula I I 3 (I) o R2 03M S 6 in which R 1 R2 and R 3 independently, are hydrogen, C02M, Cl-C 4 alkyl or phenyl, but preferably Ri, R 2 and R 3 are each hydrogen; and M is hydro- S gen, an alkali- or alkaline earth metal, ammonium or an amine residue; B is a moiety having the formula II (II) in which R4 and Rs, independently, are hydrogen, phenyl, Ci-Cqalkyl (optionally substituted by an hydroxyl group or a carboxyl group, or interrupted by an nxygen atom or a carbonyl group), S03H, halogen, hydroxyl or Ci-Csalkoxy, R4 and Rs preferably each being hydrogen; X is hydrogen or -COzM wherein M has its previous significance; and Y is -C0 2 M wherein M has its previous significance or X and Y together way form an anhydride group; and D is a moiety different from B and having the formula III 6 7 (III) wherein Rs is hydrogen, methyl or a residue -COORs in which Ra is hydrogen or CI-C4alkyl group; R7 is hydrogen, C 1 -C4alkyl, hydroxymethyl or -COOR 9 in which Rs is hydrogen or a residue of formula IV LU-I 0 -CHz-Cni CHz (IV) or R 9 is a straight or branched chain alkyl having 1 to 4 carbon atoms or C1-C4alkyl substituted by -SO3M or by -COOM where M has its previous significance; Z is -COOR 9 where R 9 is as defined above, or Z is a straight or branched alkyl having 1 to 4 carbon atoms or said alkyl substituted by one to three carboxylic acid groups; or Z is phenyl or said phenyl substituted by -S03M or by -P03M 2 or Z is acetoxy, hydroxy, hydroxymethyl, acetoxy- methyl, -CH 2 SO3M, -CH 2 P03H2, -P03M 2 or -P03M' 2 in which M has its previous significance and M' is M or alkyl of 1 to 4 carbon atoms; or Z is a residue -CONR 1 1 R 1 2 wherein R 1 1 and R 12 are the aa or different and each is hydrogen, straight or branched chain alkyl having 1 to 4 carbon Satoms, hydroxymethyl, -CH(OH)COOM, -C(CH 3 2 CH 2 S0 3 M, -C(CH 3 2 CH 2 PO3M2 or -N(R 1 3 )COCH 3 in which R 1 3 is hydrogen or straight or branched chain alkyl of 1 to 4 carbon atoms and M has its previous significance; m is an integer, n is 0 or an integer and p is 0 or an integer. 2. A method according to claim 1 in which the the values of m, n and p being such that the molecular weight of the polymer ranges from 500 to 10,000 while retaining its water solubility. 3. A method according to claim 1 in which A constitutes 100 to 10 of total polymer; B constitutes 0 to 90 of total polymer; and D constitutes 0 to 25 of total polymer, each by weight of total polymer. 4. A method according to claim 1 wherein A is derived from vinyl sulfonic acid, 8-styrenesulfonic acid, 1-propene sulfonic acid, 2-propene sulfonic acid and sulfomaleic acid. A method according to claim 3 wherein A is derived from vinyl sulfonic acid. 6. A method according to claim 1 wherein B is derived from acrylic acid, methacrylic acid, maleic acid or anhydride or fumaric acid. MW-

16- 7. A method according to claim 1 in which the polymer is added to the water in an amount ranging from 1 to 200 ppm, based on the weight of the water to be treated. 8. A method according to claim 7 wherein the polymer is added in amount ranging from 1 to 30 ppm, based on the weight of water to be treated. 9. A method according to claim 1 in which the polymer is added to the water together with one or more cf corrosion inhibitors; dispersing and/or threshold agents; precipitating agents; oxygen scavengers; Ssequestering agents; antifoaming agents; biocides and demulsifiers. °9 10. A method according to claim 9 in which the polymer is added to the water together with one or more of polymaleic acid or polyacrylic acid or their copolymeus, or substituted copolymers, HEDP, PBSAM, triazoles such as tolutriazole, molybdates and nitrites. DATED this 17th day of May, 1991. CIBA-GEIGY AG By Its Patent Attorneys ARTHUR S. CAVE CO. i 7 y^'