CA1180176A

CA1180176A - Friction reduction using a viscoelastic surfactant

Info

Publication number: CA1180176A
Application number: CA000414512A
Authority: CA
Inventors: Arthur S. Teot; Gregory A. Stevens; Gene D. Rose
Original assignee: The Dow Chemical Company; Arthur S. Teot; Gregory A. Stevens; Gene D. Rose
Current assignee: Dow Chemical Co
Priority date: 1981-10-30
Filing date: 1982-10-29
Publication date: 1985-01-02
Also published as: DK158337B; US4615825A; DK301583A; FI832314L; NO163357C; DE3273881D1; DK301583D0; WO1983001583A1; EP0092581A4; EP0092581B1; ATE23020T1; JPS58501822A; FI832314A0; DK158337C; NO163357B; FI70152C; FI70152B; NO832359L; EP0092581A1

Abstract

ABSTRACT OF THE DISCLOSURE
This invention is directed to a method for reducing friction exhibited by an aqueous liquid passing through a conduit under nonlaminar flow conditions and to aqueous liquid compositions having such reduced friction containing a viscoelastic surfactant and an organic electrolyte. The method comprises passing through a conduit an aqueous liquid containing (1) a surfactant compound having a surfactant ion and (2) an organic electrolyte having a moiety that is capable of associating with the surfactant ion to form a viscoelastic surfactant, the viscoelastic surfactant being present in an amount sufficient to reduce the friction of the aqueous liquid as it passes through the conduit and the organic electrolyte being present in an amount sufficient to further reduce the friction exhibited by the aqueous liquid containing the viscoelastic surfactant as it passes through a con-duit under conditions of nonlaminar flow. The aqueous liquid compositions are useful in district heating systems, drilling fluids, waste water systems and as a carrier in transporting coal slurries and other minerals.

28,258-F

Description

METHOD FOR REDUCING FRICTION EXHIBITED BY AN
AQUEOUS LIQUID DURING NONLAMINAR FLOW AND
AQUEOUS LIQUID COMPOSITIONS HAVING SUCH REDUCED
FRICTION CONTAINING A VISCOELASTIC SURFACTANT AND
AN ORGANIC ELECTROLYTE

In the flow of an aqueous liquid through a conduit, energy is required to overcome the friction created by the turbulence of the liquid flowing through the conduit. In many operations such as indu`strial applications, particularly those operations in which the velocity of the flowing aqueous liquid exceeds the limit required for smooth laminar flow (e.g., well fracturing treatments or the rapid movement of liquids for considerable distances), substantial expenditures of energy are required to overcome the friction losses.
A reduction in the friction loss exhibited by a flowing aqueous liquid would permit lower amounts of energy expenditures and/or increased flow using the same energy.

Heretofore, various alternatives have been proposed to reduce the friction loss exhibited by a fIowing aqueous liquid. For example, water-soluble, high molecular weight polymers such as a polymer of a monoalkenyl aromatic sulfonate (e.g., styrene sulfonic acid) or a polymer of a carboxamide (e.g., acrylamide) 28,25~-F -1-are known to reduce friction loss when added to an aqueous liquid in small amounts. See, for example, U.S. Patents 3,023,760; 3,562,226 and 3,572,354.
Unfortunately, the aqueous liquid systems containing the high molecular weight polymers are not shear stable, i.e., the friction reduction exhibited by the liquid containing said polymer is substantially and permanently lost when subjected to high shear.

Friction losses in a flowing aqueous liquid have also been reduced by the addition of a surfactant which imparts viscoelastic properties to the aqueous liquid. For example, U.S. Patent 3,361,213 to Savins teaches that an alkali metal soap of a fatty acid, e.~., sodium oleate, in combination with a strong electrolyte will reduce the friction of an aqueous liquid. Similarly, Savins discloses that (1) an ammonium soap of a fatty acid will reduce the friction losses exhibited by an aqueous liquid containing a weak electrolyte and (2) a substituted ammonium soap of a fatty acid will reduce the friction losses of an aqueous; liquid containing no electrolyte. Other visco-elastic surfactants such as 2-naphthol in combina-tion with cetyl trimethyl ammonium bromide are also known to be useful as friction reducing agents. Although such viscoelastic materials often reduce the friction exhi-bited by an aqueous liquid flowing through a conduit, further reductions in friction over broad flow ranges are often desired, particularly in those operations wherein relatively large amounts of aqueous fluid are to be pumped over long distances.

In view of -the aforementioned deficiencies of the prior art, it is highly desirable to further reduce 28,-258-F -2~

the friction losses exhibited by a flowing aqueous liquid.

Accordir.gly, in one aspect, the present invention is a method for reducing the friction exhibited by an aqueous liquid passing through a conduit under nonlaminar flow conditions. By "nonlaminar flow" is meant the flow of a fluid through a conduit at a Reynolds number sufficiently high to cause an increase of the friction factor of the fluid including well-developed turbulent flow. This method comprises passing through a conduit an aqueous liquid containing (1) a surfactant compound having a hydro-phobic moiety chemically bonded to an ionic, hydro-philic moiety (hereinafter a surfactant ion) and (2) an lS organic electrolyte having a moiety that is capable of associating with the surfactant ion to form a visco-Plastic surfactant. For the purposes of this invention, a viscoelastic surfactant is a compound having (1) an ion capable of acting as a surfactant and (2) a stoichi-ometric amount of an organic counterion that associateswith the surfactan-t ion to render it viscoelastic as defined hereinafter. The resulting viscoelastic surfac-tant is present in an amount sufficient to reduce the friction of the aqueous liquid as it passes through the conduit. The organic electrolyte, which can associate as the counterion with the surfactant ion to form a viscoelastic surfactant, is present in an amount sufficient to further reduce the friction exhibited by the aqueous liquid containing the viscoelastic surfac-tant when it passes through a conduit under conditionsof nonlaminar flow.

28,258-F 3-In another aspect, the present invention is an aqueous liquid composition comprising (1) an aqueous liquid, (2) a friction reducing amount of a viscoelaskic surfactant having a (a) surfactant ion and (b) an organic electrolyte having a moiety that is capable of associating with the surfactant ion and (3) additional organic electrolyte present in an amount sufficient to further reduce the friction exhibited by the aqueous li~uid containing the visco-elastic surfactant as it passes through the conduitunder conditions o~ nonlaminar flow.

Surprisingly, the presence of the organic electrolyte in an agueous liquid containing the visco-elastic surfactant in accordance with the practice of this invention significantly fur-ther reduces the fric-tion exhibited by the agueous fluid containing the viscoelastic surfactant as the liquid flows through a conduit. The admixture of the aqueous liquid, organic electrolyte and viscoelastic surfactant is significantly more shear stable than an agueous liquid containing a polymer capable of providing the aqueous liquid with the same degree of friction reduction. Moreover, the admixture exhibits an unexpectedly large reduction in friction over a wide range of conditions that produce nonlaminar flow.

The method and composition of this invention are useful in those processes where water or other agueous liquid is pumped or circulated in pipes or other conduits such as in air conditioners and other heat exchangers, slurry pipelines often used to trans-port coal and various minerals and other operations requiring large amounts of energy for pumping the aqueous liguid.

28,258-F -4-' :

As used herein, the term "aqueows liquid"
refers to those liquids which contain water. Included within the term are aqueous li~uids con-taining inor-ganic elec-trolytes, such as aqueows alkaline or aqueows acidic solutions, e.g., an aqueous solution of an alkali metal or alkaline earth metal hydroxide, and aqweous solutions of inorganic salts. Other exemplary aqueous liquids include mixtures of water and a water-miscible li~uid such as lower alkanols, e.g., methanol, ethanol or propanol; glycols and polyglycols and the like provided that such water-miscible liquids are employed in amounts that do not deleteriously affect the viscoelastic properties of the aqueous liquid.
Also included are a~ueous slurries of solid particu-lates such as coal particles and finely divided mineralores. In general, however, water and aqueous alkaline, aqueous acidic or aqueous inorganic salt solutions are most beneficially employed as the aqueous liquid herein.
Advantageously, the electrolyte concentration is less than 15, preferably less than 12, more preferably less than 5, especially less than 1, percent by weight of the solution. Most preferably, the aqueous liquid is water.

The term "viscoelastic" as it applies to liquids, means a viscous liquid having elas-tic proper-ties, i.e., the liquid at least partially returns to its original form when an applied stress is released.
The property of viscoelasticity is well-known in the art. Reference is made to H. A. Barnes et al., heol. Acta, 1975 14, pp. 53-60 and S. Gravsholt, Journal of Coll. and Interface Sci., 57 (3) pp. 575-6 (1976) for a definition of viscoelasticity and tests to determine whether a liguid possesses viscoelastic 28,258-F -5~

properties. of the test methods specified by these references, a tes-t which has been ~ound to be most useful in determining viscoelasticity of an aqueous solution consists of swirling the solution and visually observing whether the bubbles created by the swirling recoil after the swirling is stopped.
Any recoil of the bubbles indicates viscoelasticity.
Accordingly, a viscoelastic surfactant imparts viscoelasticity to the liquid to which it is added.

In general, surfactant compounds comprise an ionic hydrophobic molecule having an ionic, hydro-philic, moiety chemically bonded to a hydrophobic moiety (herein called a surfactant ion) and a counter-ion sufficient to satisfy the charge of the surfactant ion. Examples of such surfactant compounds are represented by the formula:

R1tY~)Xe or Rl(Ze)A~

wherein Rl(Y~) and Rl( za ) represent surfactant ions ha~ing a hydrophobic moiety represented by Rl and an ionic, solubili2ing moiety represented by the cationic moiety (Y~) or the anionic moiety (Ze) chemically bonded thereto. X~ and A~ are the counterions associ-ated with the surfactan-t ions.

In general, the hydrophobic moiety (i.e., R1) of the surfactant ion is hydrocarbyl or inertly substi-tuted hydrocarbyl wherein the term "inertly substituted"
refers to hydrocarbyl radicals having one or more substituent groups, e.g., halo groups such as -Cl or -Br, or chain linkages, such as a silicon linkage (-Si-~ which are inert to the aqueous liquid and 28,258-F -6-~:~80~76 components contained therein. Typically, the hydro-carbyl radical is an aralkyl group or a long chain alkyl or inertly substituted alkyl, which alkyl groups are generally linear and have at least 12, advan-tageously at least 16, carbon atoms. Representa-tive long chain alkyl groups include dodecyl (lauryl), tetradecyl (myristyl), hexadecyl (cetyl), octadecyl (stearyl~ and the derivatives of tallow, coco and soya.
Preferred alkyl groups are generally alkyl groups having from 14 to 24 carbon atoms, with octadecyl, hexadecyl, eurcyl and tetradecyl being the most preferred.

The cationic, hydrophilic moieties (groups), i.e., (Y~), are generally onium ions wherein the term "onium ions" refers to a cationic group which is essen-tially completely ionized in water over a wide range of pH, e.g., pH values from 2 to 12. Representative onium ions include quaternary ammonium groups, i.e., -N~(R)3; tertiary sulfonium groups, i.e., -S~(R)2;
and quaternary phosphonium groups, i.e., -P~(R)3 wherein each R is individually a hydrocarbyl or inertly substituted hydrocarbyl. In addition, primary, secondary and tertiary amines, i.e., -NH2, -NHR or -N(R)2, can also be employed as the ionic moiety if the pH of the aqueous liquid being used is such that the amine moieties will exist in ionic form. of such cationic groups, the surfactant ion of the viscoelastic suxfactant is preferably prepared having quaternary ammonium, -N~(R)3, or tertiary amine, -N(R)2, groups wherein each R i5 independently an alkyl group or hydroxyalkyl group having from 1 to 4 carbon atoms, with each R preferably being methyl, ethyl or hydroxy-ethyl.

28,258-F -7-~8~7~

Representative anionic, solubilizing moieties (groups) (Z9) include sulfate groups, i.e. -OS03e, sulfonate groups, i.e., -S03e, carboxylate groups, i.e., -Coo , phosphonate groups, and phosphonite groups.
Of such anionic ~roups, the surfactant ion of the viscoelastic surfacta~ts is preferably prepared having a carboxylate or sulfate group. For purposes of this invention, such anionic solubilizing moieties are less preferred than cationic moie-ties.

The counterions (i.e., Xe or A~) associated with the surfactan-t ions are suitably ionically charged, or~anic materials having ionic character opposite that of the surfactant ion, which combination of counterion and surfactant ion imparts viscoelastic properties to an aqueous liquid. The organic material having an anionic character serves as the counterion for a surfac-tant ion having a cationic, hydrophilic moiety and the organic material having a cationic character serves as the counterion for the surfactant ion having an anionic, hydrophilic moiety. In general, the preferred counter-ions exhibiting an anionic character contain a carboxy-late, sulfonate or phenoxide group wherein a "phenoxide group" is ArOe and Ar represents an aromatic ring or inertly substituted aromatic ring. Representative of such anionic counterions which, when employed with a cationic surfactant ion, are capable of imparting viscoelastic properties to an aqueous liquid include various aroma-tic carboxylates such as o-hydroxybenzoate;
m- or ~-chlorobenzoate, methylene bls-salicylate and 30 3,4-, 3,5- or 2,4-dichlorobenzoate; aromatic sulfonates such as p-toluene sulfonate and naphthalene sulfonate;
phenoxides, particularly substituted phenoxides such as the halogenated phenoxates including 2,6-, 2,5- or 28,258-F -8-`~

~8~7~
g 3,5-dichlorophenate, 2,4,5-trichlorophenate or

2,3,5,6-tetrachlorophenate; and alkyl substituted phenates such as t-butyl phenate, t-bu-tyl hydroxy-phenate and 4-ethyl phenate. Alternatively, the cationic counterions may contain an onium ion, most preferably a quaternary ammonium group. Representative cationic counterions containing a quaternary ammonium group include benzyl trimethyl ammonium or alkyl tri-methyl ammonium wherein the alkyl group is advanta-geously octyl, decyl, or dodecyl. The use of acation as the counterion is generally less preferred than the use of an anion as the counterion.

The particular surfactant ion, and the counterion associated therewith are selected such that 15` the combination imparts viscoelastic properties to an aqueous liguid. Of the aforementioned surfactant ions and counterions, those combinations which form such viscoelastic surfactants will vary and are easily determined by the test methods hereinbefore described.
Of the surfactants which impart viscoelastic properties to an aqueous liquid, the preferred surfactant compounds include those represented by the formula:

H3 4CH2~n N R X

wherein n is an integer from 13 to 23, preferably an integer from 15 to 19; each R is independently hydrogen or an alkyl group or a hydroxyalkyl group having from l to 4 carbon atoms, preferably each R

28,258-F -9-is independently methyl or ethyl and Xe is o-hydroxy benzoa-te, _- or ~-halobenzoate or _- or ~-alkylben~
zoate wherein the alkyl group is advantageously from 1 to 4 carbon atoms.

The viscoelastic surfactants are easily prepared by admixing the basic form of the desired cationic surfactant ion (or acidic form of the desired anionic surfactant ion) with a stoichiometric amount of the acidic form of the desired cationic counterion (or basic form of the desired anionic counterion). Alter-natively, stoichiometric amounts of the salts of the cationic surfactant ion and the anionic counterion (or equimolar amounts of the anionic surfactant ion and cationic counterion) can be admixed to form the visco-elastic surfactant. See, for example, the proceduresdescribed in U.S. Patent 2,541,816.

The viscoelastic surfactant is employed in an amount sufficient to impart viscoelastic properties to the aqueous liquid, wherein the viscoelasticity of the aqueous liquid is measured by the techniques described herein. In general, such amount of viscoelastic surfactant is sufficient to measurably reduce, prefer-ably by at least 5 percent, the friction exhibited by the aqueous liquid as the liguid flows through a conduit under conditions sufficient to provide nonlaminar flow.
For the purposes of this invention, the friction exhib-ited by the flowing aqueous liquid is measured using conventional techniques such as set forth in Example 1.
The specific viscoelastic surfactant employed and the concentration thereof in the aqueous liquid are depen dent on a variety of factors including solution compo-sition, temperature, and shear rate to which the flowing 28,258-F -10-~L18~76 liquid will be subjected. In general, the concentration of any specific viscoelastic surfactant most advantage-ously employed herein is easily determined by experimen-tation. In general, the viscoelastic surfactants are preferably employed in amounts ranging from 0.01 to 5 weight percent based on the weight of the surfactant and agueous liquid. The viscoelastic surfactant is more preferably employed in amounts from 0.05 to 0.5 percent based on the weight of the aqueous liquid and the viscoelastic surfactant.

In the practice of this invention, an organic electrolyte having an ionic character opposite to that of the surfactant ion and capable of being associated as an organic counterion with said surfactant ion is employed to further reduce the ~riction exhibited by the aqueous liquid containing the viscoelastic sur-factant as it passes through a conduit under conditions of nonlaminar fIow. Such organic electrolytes suitably employed herein include those containing organic ions which, when associated with the surfactant ions of the surfactant compound, form a viscoelastic surfactant.
The organic electrolyte, when present in an excess of that which associates with the surfactant ion, is capable of further reducing friction of the aqueous liquid passing through the conduit. Such organic electrolyte is soluble in the aqueous liquid containing the viscoelastic surfactant.

In general, the oxganic ions are formed by the dissociation of corresponding organic electrolytes, including salts and acids or bases of a suitable organic ion. For example, an organic electrolyte which, upon dissociation, forms an anion which will fur-ther reduce 28,258-F

1~8~76 -12~

the friction of an aqueous liquid containing a visco-elastic surfactant having a cationic surfactant ion.
Examples of such anionic organic electrolytes include the alkali metal salts of various aromatic carboxylates such as the alkali metal aromatic carboxylates, e.g., sodium salicylate and potassium salicylate and disodium methylene-bis(salicylate); alkali metal ar-halobenzoates, e.g., sodium ~-chlorobenzoate, potassium m-chlorobenzo-ate, sodium 2,4-dichlorobenzoate and potassium 3,5-di-chlorobenzoate; aromatic sulfonic acids such as p-toluene sulfonic acid and the alkali metal salts thereof;
napthalene sulfonic acid; and phenols and substituted phenols, e.g., ar,ar-dichlorophenols, 2,4,5-trichlor-phenol, t-butylphenol, t-butylhydroxyphenol, and ethyl-phenol.

A suitable cationic organic electrolyte upondissociation, forms a cation useful in further reducing the friction of an aqueous liquid containing a visco-elastic surfactant having an anionic surfactant ion.
While cationic organic electrolytes are less preferred than the aforementioned anionic organic electrolytes, exa~ples o~ suitable cationic electrolytes include the quaternary ammonium salts such as alkyl trime-thyl-ammonium halides and alkyl triethylammonium halides wherein the alkyl group advantageously contains 4 to 10 carbons and the halide advantageously is chloride; aryl and aralkyl trimethyl ammonium halides such as phenyl trimethyl and benzyl trimethyl ammonium chloride; alkyl trimethyl phosphonium halides and the like. Preferably, the organic elec-trolyte is the same or generates the same ion associated with the surfactant ion of the viscoelastic surfactant contained by the aqueous liquid, e.g., alkali metal salicylate is advantageously employed 28,258-F -12-~ -13-as the additional organic electrolyte when the visco-elastic surfactant is originally prepared having a salicylate counteri~n. Therefore, the most preferred organic electrolytes are the alkali metal salts of an aromatic carboxylate, for example, sodium salicylate.

In the practice of this invention, sufficient amounts of the organic electrolyte are employed to further reduce the friction exhibited by the aqueous liquid containing the viscoelastic surfactant as it passes through a conduit. The friction of the aqueous liquid is that friction as measured using the test method set forth in Example 1. By "reduce the friction"
is meant that, by test method described in Example 1, the friction of an aqueous liquid containing the visco-elastic surfactant and the organic electrolyte (i.e.,the aqueous liquid containing a number of sui-table organic ions in excess of that number required to fully balance the charge of the surfactant ion) is less than the friction exhibited by an aqueous liquid having an identical concentration of the viscoelastic surfactant but containing no additional organic electrolyte.
Preferably, the organic electrolyte is employed in amounts such that, when the flow characteristics as defined by the Reynolds number are constant, the fric-tion exhibited by the flowing a~ueous liquid containingthe viscoelastic surfactant and organic electrolyte is at l~ast S, more preferably at least 10, percent less than an aqueous liquid that is identical in all respects except that it contains no excess organic ions. The Reynolds number (Re) is the product of the density (p) of the aqueous liquid expressed in grams per cubic centimeter (g/cm3), the mean velocity (v) of the liquid flowing through the co~duit expressed 28,258-F -13-in centimeters per second (cm/sec) and the dia~eter (d) of the conduit expressed in centimeters (cm) divided by the viscosity (~) (poise) of the aqueous liquid, i e., Re = e~

In general, as the flow characteristic of an aqueous liquid changes such that the Re increases, the friction exhibited by the flowing liquid decreases until the flow becomes nonlaminar as defined hereinbefore.
Advantageously, the concentration of the organic ions which produces the desired further reduction in friction is such that the Re, at which this decrease in friction occurs, is increased. The aqueous liquid contains sufficient amounts of the organic electrolyte such that the level of friction at nonlaminar flow is reduced.
This level of friction monotonically decreases with increasing Re to Re greater than those aqueous liquids containing no organic electrolyte.

The concentration of organic electrolyte reguired in the aqueous liquid to impart such further reduction in friction is dependent on a variety of factors including the particular aqueous liquid, viscoelastic surfactant and organic electrolyte employed and the achieved reduction in friction. In general, the concentration of the organic electrolyte will advantageously range from 0.1 to 20, preferably from l to 5, moles per mole of the viscoelastic sur-factant.

The aqueous liquids having reduced fric-tion when passing through a conduit are readily prepared by admixing the desired amounts of the viscoelastic sur~
factant and organic electrolyte to form an aqueous 28,258-F -14-., ~

liquid solution. The resulting solution, which solu-tions are stable and can be stored for long periods, can be employed as prepared for various purposes such as in fire fighting systems, industrial processing, in operations such as heat exchange and air conditioning, as a carrier in transpor-ting coal slurries and other minerals. In addition, other optional ingredients can be added to the aqueous liquid to render the liquid suitable for various applications such as fracturing fluids, drilling muds, agricultural sprays and cutting fluids.

The following examples are presented to illustrate the invention and should not be construed to limit its scope. All percentages and parts are by weight unless otherwise indicated.

Example 1 and Comparative Runs A, B and C
The composition of Example 1 was prepared by admixing 99.5 parts of water, 0.25 part of a visco-elastic surfactant of cetyltrimethylammonium salicylate (CTAS) (prepared using equimolar amounts of cetyltri-methylammonium hydroxide and salicylic acid) and 0.27 part of sodium salicylate (NaS). To determine the friction exhibited by the resulting solution 10wing through a conduit, the ~-elocity of the liquid as it flows through a length of a conduit at a known pres-sure drop was measured using an apparatus comprising a suitably sized reservoir for holding the aqueous liquid, the reservoir being connected to a circular conduit constructed of glass and having an inside diameter of 2.65 mm and a length of 100 cm. The reservoir was fitted such that a predetermined pressure could be applied to any liquid contained 28,2S8-F - -15-~8~1~7~

therein and maintained constant throughout the time reguired for the desired amounts of liguid to flow the length of the circular conduit. The other end of the circular conduit was connected to a graduated receptacle which is maintained at atmospheric pressure. In opera-tion, while maintaining the pressure on the aqueous liquid constant, the liguid was allowed to flow throuyh the circular conduit using the applied pressure as a driving force. The liquid flowing through the conduit was collected in the receptacle and the mean velocity of the liguid in the conduit was determined by measuring the amount of liquid collected and dividing by the time reguired to collect the liquid.

In this Example, separate portions were passed through the circular conduit using the various pressures specified in Table I. These pressures resulted in various mean velocities of the liguid in the circular conduit, which velocities are specified in Table I. From the predetermined pressures and measured velocities, a friction factor was calculated using the eguation:

f D~
~pLV

wherein: f = Fanning friction factor D = diameter of the circular conduit through which the liquid is passed, expressed in cm (0.265 cm) ~P = pressure drop of the liguid as it flows through the circular conduit in g/cmZ
g = 980.6 cm/sec2 p = density of agueous liquid in g/cm3 (~1 g/cm3) 28,258-F -16-L = length of condui-t through which li~uid flows in cm (100 cm) V = velocity of liquid in cm/sec In a similar manner, the friction of water (Comparative Run A) and wa-ter containing 0.25 weight percent cetyl trimethylammonium salicylate with no additional sodium salicylate (organic electrolyte) ~Comparative Run B) are determined. The results of the testing are also recorded in Table I. The concentrations of the viscoelastic surfactant and the organic electrolyte are expressed as weight percent based on the total formulation. For the organic electrolyte, the composition is also expressed in parenthesis in terms of moles per mole of viscoelastic surfactant (M/M).

28,258-F 17-~18~

_.~
~ ~ ~Y7 ~ ~ 0 0 d1 o-- ~ ~ ~ o ~ cx~
~ ~ o o o ,~ o o o o o ~$ oooooo ooo O O O O O O O O O

oooooo ooo o o o~ ~

,_ OD O O O O O ~ u~ ,1 o \ ,` U~ ~ ~ o ~ U~ U~ o o~ ~ ~ ~ Ln a) o ~1 h ~ ~ ~ r` ~1` t` In t~ t`
::~ ~
Ul O ` ~ N ~ N ~1 u~ h--S~ ~

~_ ~:
,~ .
E~~ O ~ ~`
~ ~ ~ ~ l l ~ o ~ ~ ~ o o ~ ~ ~
~ ~ u~
~ ~ l l ~ z;
E~
~ ~ o - -~ ~ ~ ~ l ~
~ ~ o ~ c) o o O ~ q~l ~ ` u~
~n u~ ~ E~ E~
~ E~ V C~

s~ ~
o ~
~1 ~IY;
~ ~ ~ ~: m ~ V

28, 258-F -18-As evidenced by Table I, the aqueous liquid composition containing excess amounts o~ the organic electrolyte exhibits lower friction than water (Com-parative Run A) or water containing only the visco-elastic surfactant (Comparative Run C). In addition,the aqueous liquid containing only the viscoelastic surfactant (Comparative Run B) shows increased friction at a Re of between 14,750 and 18,580 and water (Comparative Run A) shows a similar increase in friction at a Re of about 2,300, which increase in friction indicates the onset of nonlaminar flow.
Unexpectedly, at Re up to 27,230, the aqueous liquid containing both the viscoelastic surfactant and excess amounts of the organic electrolyte exhibit no such increase in friction.

In addition, the aqueous liquid composition of Example 1 was sheared for two minutes at high speed in a Waring Blendor and the friction remeasured using the same pressures. The sheared composition was found to exhibit the same friction as the composition before shearing, thereby indicating that the composi- -tions of the invention are shear stable.

For Comparative Run C, an a~ueous liquid containing 0.0125 weight percent of a partially hydro-lyzed acrylamide polymer having a weight average mole-cular number of 3-4 million (calculated fxom viscosity) was tested in a similar manner and found to exhibit essentially the same fricti.on at equivalent Re as Example 1. However, after shearing the aqueous liquid at high speed in a Waring ~lendor for 2 minutes, the friction exhibited by the aqueous liquid was signifi-cantly increased, e.g, the aqueous li~uid subjected to 28,258-F -19-~31 8~7~

shear and having flow characteristics defined by a Re of 19,000 has a friction of 0.068 whereas the aqueous liquid which has not been sheared exhibits a friction of only 0.037 at fl.ow characteristics defined by the same Re.

Examples 2, 3 and 4 and Comparative Runs A, D and E
Following the procedures of Example 1, the friction of aqueous liquid compositions (Examples 2-4) containing 99.8 parts of water, 0.1 part of cetyl-trimethylammonium salicylate (CTAS) and the variousamounts of sodium salicylate (NaS) specified in Table II were measured at the various Re specified in Table II. For purposes of comparison, the fric-tion values of water (Comparative Run A) and an aqueous liquid composition of 99.9 parts of water and 0.1 part of cetyl trimethylammonium salicylate (Comparative Run B) were determined at the Re specified in Table II.

28,258-F ~20-O--~ ~ ~ ~ O ~ O ~D ~O
~O OOO OOo Ooo ,~,~o ooo U~ 000 ooo ooo ooo ooo ,1~) ... ... ... .... ...
S~0 ooo ooo ooo ooo ooo ooo ooo ooo ooo ooo a) O Q O O O O O O O O O O O O O
P; U~ 0~ 0 t` OD t` ~ ~O O Lr) ~ 'I

_ ~
co r~ ~D
O ~ ~
. ~ ~ ~D
~ ~ ~) ~ d1 ~
rl~ ~ O O O
~ O O
H~1 O ' O O
1 1 ~ 0 a~ ~ a~u~
~~ ~ 0 f~ I I
E~ E~ ~; ~ Z

~ 1 ~ ~
O O O O O
t~ ~ ~) O
t) h a~ v~ 1 u~
~ ~ ¢ ! t I
rl U~ ;~ E~
E~ V V ~) V

~ a~
O
., a~ ~

~C ~ <~ Q
O

28, 258-F 21-As evidenced by the data in Table II, the concentra-tion of the organic electrolyte affects the friction exhibited by the aqueous liquid containing the same. Generally, greater reduction in friction is evidenced with increasing concentrations of organic electrolyte up to a maximum.

For Comparative Run E, an aqueous liquid containing the viscoelastic surfactant and potassium chloride, an inorganic electrolyte, with the Cl~ being capable of acting as the counterion for the cetyl tri-methylammonium radical, was prepared. Although results equivalent to those obtained using an organic electro-lyte of sodium salicylate were achieved, a relatively high concentration of 0.5 weight percent KC1, based on the weight of the water and viscoelastic surfactant, was required.

Examples 5, 6 and 7 and Comparative Runs A and F
Following the procedures of Example 1, the friction of aqueous liquid compositions of E~amples 5-7 containing 99.8 par-ts of water, 0.1 part of tetradecyl trimethylammonium salicylate (MTAS) and the various amounts of sodium salicylate (NaS) specified in Table III were measured at the various Re specified in Table III.

For purposes of comparison, the friction values of water (Comparative Run A) and an aqueous liquid composition of 9`9.9 parts of water and 0.1 part of tetradecyl trimethylammonium salic~late (Comparative Run F) were determined at the Re specified in Table III. The results of these determinations are reported in Table III.

28,258~F -22-7~

o-- a) oo dl C~ O ~ d~1` ~ ~ ~ CO ~ ~ d1 ~ U~ o l`
~O OOOO OOOO OOOOO ~1~O OOOO
oooo oooo ooooo ooo oooo .... .... ..... ... ....
h ~ oooo oooo ooooo ooo oooo ~t~ ~Ln~ ~00~9 ooo~,~oD
O CO ~ CO ~ O <J~ In CO O O O O
~ O ~ d1 ~ ~ ~ ~o o d1 CO ~ o Lr) ~ o 1` ~ ~ t`
P; ~D ~ ~ U~ ~ U~ O t` ~ u~ ~1 ~ ~ ~ ~ ~ r--~ O ~
~I N ~ r-1 N N rJ~ N N ~ ~1 ~ l N

,_ ~ Ln ~ ~
$ ~` ~
U ~ . Lfl O O
O ~I t'') U') ~ I
H ~ O ~
,_, ~a ~, o o o o ~ ~ V
~3 O
m ~ ~ u~
i~3 ~ ~; ~i Z

~) . U~ 11~ Ln Ln ~n ~ o o o o o ~ ~ u o ~
~ u~
I
>

~o s a) ~) ~ ~ u~
~ o u 28, 258-F -23-8t:~7E;

As evidenced by the data of Table III, the relationship of friction to the addition of organic electolyte to an aqueous liquid containing a visco-elastic surfactant is similar ~o that shown in Tables I
and II.

Examples 8 - 14 and Comparative Runs A, G and H
Following the procedures of Example 1, the friction of aqueous liquid compositions of Examples 8-14 containing 99.8 parts of water, 0.1 part of cetyl trimethylammonium salicylate (CTAS) or cetyl trimethylammonium 3,4-dichlorobenzoate (CTADCB) and the various amounts of sodium salicyl-ate (NaS) and sodium 3,4-dichlorobenzoate (NaDCB) specified in Table IV were measured at the various Re specified in Table IV.

For purposes of comparison, the friction values of water (Comparative Run A), an aqueous liquid composition of 99.9 parts of water and 0.1 part of cetyl trimethylammonium salicylate (Comparative Run G), and an aqueous liquid composition of 99.4 parts of water and 0.1 part of cetyl trimethylammonium

3,4-dichlorobenzoate (Comparative Run H) were deter mined at the Re specified in Table IV. The results of these determinations axe reported in Table IV.

28,258-F -24-~ .

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O
t~ OOOO OOOO OOOO OOOO OOOO

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-26-~

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~1X ~3 N ~ d 28, 258-F -26--27~

Examples 15 ~ 18 and Comparative Run B
Following the procedures o Example 1, the friction of aqueous compositions containing 5 ~79 parts of water, 20 parts of ethylene glycol, 0.25 part of cetyl trimethylammonium salicylate (CTAS) and various amounts of sodium salicylate (NaS) as specified in Table V were measured at the various Re specified in Table V.

For Comparative Run B, the friction values of an aqueous composition of 79.75 parts of water, 20 parts of ethylene glycol and 0.25 part of CTAS were determined at the Re specified in Table V.
The results of these determinations are reported in Table V.

28,258-F ~27-~8~ 7~

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28, 258-F -28-

Claims

1. A method for reducing friction exhibited by an aqueous liquid passing through a conduit under nonlaminar flow conditions wherein the method comprises passing through a conduit an aqueous liquid containing (1) a surfactant compound having a surfactant ion and (2) an organic electrolyte having a moiety that is capable of associating with the surfactant ion to form a viscoelastic surfactant, the viscoelastic surfactant being present in an amount sufficient to reduce the friction of the aqueous liquid as it passes through the conduit and the organic electrolyte being present in an amount sufficient to further reduce the friction exhibited by the aqueous liquid containing the viscoelastic surfactant as it passes through a conduit under conditions of nonlaminar flow.

2. An aqueous liquid composition comprising (1) an aqueous liquid, (2) a friction reducing amount of a viscoelastic surfactant having (a) a surfactant ion and (b) an organic electrolyte having a moiety that is capable of associating with the surfactant ion and (3) additional organic electrolyte present in an amount sufficient to further reduce the friction exhibited by the aqueous liquid containing the viscoelastic surfactant as it passes through a conduit under conditions of nonlaminar flow.

28,258-F -29-

3. The composition of Claim 2 wherein the viscoelastic surfactant is cetyl trimethylammonium salicylate or tetradecyl trimethylammonium salicylate and the organic electrolyte is sodium salicylate.

4. The composition of Claim 2 wherein the viscoelastic surfactant is cetyl trimethylammonium 3,4-dichlorobenzoate and the organic electrolyte is sodium 3,4-dichlorobenzoate.

5. The composition of Claim 2 wherein the aqueous liquid contains up to 20 weight percent of ethylene glycol.

6. The composition of Claim 2 wherein the composition contains from 0.01 to 5 weight percent of the viscoelastic surfactant and from 0.1 to 20 moles of organic electrolyte per mole of the viscoelastic surfactant.

7. The composition of Claim 2 wherein the surfactant compound is cetyl trimethylammonium chloride or cetyl trimethylammonium salicylate and the organic electrolyte is sodium salicylate.

28,258-F -30-