US2888399A - Process for inhibiting corrosion in oil and gas wells - Google Patents

Description

PROCESS FOR INHIBITIN G CORROSION IN OIL AND GAS WELLS Arthur F. Wirtel, Glendale, and Charles M. Blair, Jr.,

Webster Groves, Mo., assignors to Petrolite Corporatlonywilmington, Del., a corporation of Delaware No Drawing. Application April '1, 1953 Serial No. 346,264

1 Claim. (Cl. 252-855) This invention relates to the inhibition of corrosion of metals. It includes new compositions for use in preventing corrosion of metals, in particular, iron, steel, and ferrous alloys, and the process of preventing such corrosion by application of the new compositions to the surfaces of the metals. The invention is of particular value in the prevention of corrosion of pipe or equipment which is in contact with corrosive oil-containing media as, for example, in oil wells producing corrosive oil or oil-brine mixtures, in oil refineries, and the like, but it is useful in numerous other systems or applications, as the new compositions appear to possess properties which impart to metals resistance to attack by a'variety of corrosive agents, such as brines, weak inorganic acids, organic acids, CO H 8, etc.

A wide range of corrosion inhibitors, particularly for.

use in oil and gas wells, oil refineries and the like, have heretofore been used or suggested for use. One group is that which includes amines, amido-amines and nitrogen heterocyclics characterized by the presence of two or more nitrogen atoms, at least one of which is basic, and one or more hydrocarbon groups having from 8 to 32 carbon atoms. Such compounds have a moderately strong nitrogen-containing basic group (either free or in salt form), which may be present as part of a heterocyclic ring structure, as in certain amidine, e.g., imidazoline, tetrahydropyrimidine and carbamyl compounds, or not, as in non-cyclic amino amides or polyamines. There is a substantial variation in the relative eifectiveness of such agents as corrosion inhibitors. In general, we have found that the more complex products having a plurality of basic nitrogen atoms, and in particular relatively complex amino-amides, imidazolines, tetrahydropyrimidines and carbamyl derivatives of cyclic amidines are more efiective than simpler amino compounds.

The present invention is based upon the discovery that the anticorrosive action of such agents, as a class, is markedly enhanced if they are associated with an alkylated aromatic sulfonic acid of the type hereinafter defined, or a salt thereof. We have no explanation of this observed result, as in our tests, we have not found that the alkylated aromatic sulfonic'acids which we use, or

their salts, have any marked corrosion inhibiting action.

On the other hand, we have found corrosion inhibitors, which when used conventionally reduce corrosion very substantially, have their corrosion inhibiting action markedly enhanced by admixture with about 50% of an alkylated aromatic sulfonic acid salt. Thus, in one instance, we. found that a known corrosion inhibitor (a mixture of monoand diimidazolines obtained by heating 384 pounds of tall oil and 146 pounds of triethylene tetramine for 2 /2 hours at 285 C., which possibly contained a minor proportion of amides in addition to the imidazolines) when injected at the rate of 2 gallons a week into a gas-distillate well reduced the iron content of water from the flow line at the surface from about 240 p.p.m. to 50-60 p.p.m. With this same inhibitor, injected at the samcrate, butjn admixture. with about 36 its weightof ammonium diisopropyl naphthalene sulfonate, the iron content of the water was reduced to about 10-15 p.p.m. In both cases, suitable solvents were used and the inhibiting composition was introduced. down the annulus between the casing and the tubing. .The ammonium diisopropyl naphthalene sulfonate had no substantial corrosion inhibiting properties.

Thus, the new compositions of the invention consist of admixtures of (1) a corrosion-inhibiting agent characterized by having at least two nitrogen atoms, at least one of which is basic, which may be amino groups or form portions of heterocyclic ring structures and at least one hydrocarbon group having 8 to 32 carbon atoms, with (2) an alkylated aromatic sulfonic acid, which may be represented by the formula s0; cation in which R is an alkyl radical having 3 to 12 carbon atoms, n is a number from 1 to 3, and with the requirement that the total number of carbon atoms present in (R),, is at least 6, or the formula p S 03 cation or the cation of a water-insoluble amine, such as amyl amine, cyclohexyl amine, benzyl amine, amines derived from higher fatty acids having 8 to 18 carbon atoms, such t as lauryl amine or the mixed amines derived from fats or oils, Which are commercially available, or other cation, including polyamines or the like, such as ethylenediamine,

in which case the polybasic ion can be combined with one or more sulfonic acid groups up to a ntunber equal to its number of basic groups, e.g., in the case of ethylene diamine, either one or two moles, or some intermediate amount, of sulfonic acid per mole of diamine. cation is hydrogen it is possible that this agent may form salts with the corrosion-inhibiting amine, but in most,

instances, we think that the corrosion inhibiting amine and the sulfonic acid or'sulfonate will be present in simple admixture, as the corrosion inhibiting amine will generally, and advantageously, be used in the form of a salt, as will the sulfonic acid.

In addition to these two essential constituents of the new compositions, there will normally be present addi- 1 tional conventional materials, such as solvents where the admixtures are to be used in liquid form, waxes or other solidifying agents where the products are to be used in solid stick form, and waxes or othersolidifying agents and a weighting material, such as barium sulfate or lead oxide, where the compositions are to be used The use of corrosion inhibitors, particularly for oil and 'gas well treatment, in liquid form, or in stick form with or without weighting in the form of weighted sticks.

agents, is conventional and well known, and the present invention is concerned, not with the form of application of the compositions, but with the enhancement of the corrosion inhibiting action of the nitrogen-containing agent by association therewith of the specified alkylated aromatic sulfonic acid.

In general, we have found that minor proportions of It can be hydrogen, sodium, potassium, am-

Ifthe J) the alkylated aromatic sulfonic acid based on the corrosion inhibiting compound "are adequate to produce marked'enhancement of theactivity of the composition. Thus, 10% or less of an ,alkylated aromatic sultonic acid, based on the inhibitor, produces amarked efiect. At present, we are not aware of any requirement as to an upper, limit. It, so far as we are aware, will be fixed byceconornic considerations, as useof an excess of an alkylated aromatic sulfonic acid does not reduce the enhahcement of the anticorrosion activity, nor do amounts in, excess of S to 100%, based on the corrosion inhibitor, appear to increase the enhancement beyond that obtained with to At worst, an excess serves as an additional diluent. Thus, the range we contemplate is fr om about 5%, to about 100% of the alkylated aromatic sulfonic acid, based onth'e corrosion inhibitor, but it is tojbe understood that use ,oflarger, amounts, does. not

involve departure from the invention,

As previously stated, the corrosion inhibitors used in the new compositions are characterized by the presence of (1) at least one hydrocarbon group, having 8 to 32 carbon atoms, and (2) at least two nitrogen atoms, of which at least one is basic, which may be present as part of, a heterocyclic ring structure ornot, In certain of the most effective inhibiting agents, basic nitrogen atoms amino groups, e.g., the high boiling residue from the preparation of ethylene diamine and the like. A .num-

ber of such compounds are known to serve as corrosion inhibitors. We ,have found that, as a class, their corrosion inhibiting. etficiency is enhanced by associating them with an alkylated aromatic sulfonic acid of the type described above. We shall give illustrations of suit able corrosioninhibiting compounds by reference to various patents and patent applications in which theyare described, it being understood that the present application is based on the discovery of the enhancement of the corrosion inhibition exhibited by these compounds, rather than in the compounds themselves.

'A particularly effective group of corrosion inhibiting agents are those described in Patent Re. 23,227, Blair and Gross. These compositions are cyclic amidines, particularly imidazolines characterized by having at least one hydrocarbon group containing 8 to 32 carbon atoms. The compositions may, and advantageously do, have in addition to the two nitrogen atoms which form part of the cyclic structure additionalbasic nitrogen atoms prescut as part of a side chain linked to one of the ring nitrogen atoms, as where the products are derived from triethylene tetramine, tetraethylene pentamine, or the high boiling residues from the production of these compositions, having 6, 7 or even more amino groups. The compositions of this patent constitute one class of corrosion inhibitors which is usefully employed in preparing the compositions of the present application Typical useful compounds of thistype include:

2-undecy1imidazo1ine; Z-heptadecylimidazoline;

2-pentadencyl, l-heptylimidazoline;

2-octyl, 1-hydroxyethylirnidazoline;

2-nonyl, l-decylimidazoline; 2 o1eylimidazoline;

Z-cyclohexylethyl, l-methylimidazolinet. zabietyl, l-ethyloxyethylimidazoline;r l-octadecylimidazoline;

Z-methyl, l-octylimidazoline; l-dodecyloxymethyl, 2-hydroxyrnethylimidazoline;,. l-oleoyloxyethyl, 2-chloromethylimidazoline; 1-N decylaminoethyl, 2-ethylimidazoline; l-abietyl, Z-phenylimidazoline; i%9la? rl minqe h limiqazolin n i Z-heptadecyl, l-diethylenediaminoimidazollne; Z-methyl, 1-hexadecy1aminoethylaminoethylimldazoline; l-dodecylaminopropylirnidazoline; l-stearoyloxyethylaminoethylimidazoline; Z-ethyl, 1-(N,N dodecyl, hydroxyethyl)aminoethylimidazoline; 1-steararnidoethylaminoethylimidazoline; 1- (N-dodecyl) -acetarnidoethylarninoethylimidazoline; Chloroparafiin alkylation product of l-arninoethyl, 2-

methylimidazoline.

Application Serial No. 227,944, filed May '23, 1951, Blair and Gross, now U.S. Patent No. 2,640,029, dated May 26, 1953, describes, as corrosion inhibitors, substituted tetrahydropyrimidines of the formula type:

/N?CB5 where a D isamember of; the class consistingiof, D--.R and l i; represents a divalent organic radical containing less than 25 carbon atoms, composed of elements from the group consisting of C, H, O, andN; R isa member of the class consisting of hydrogen and hydrocarbon radicals, with ;the proviso that at least one; occurrence, of R contains from 8 to 32 carbon atoms; B is amember of the class consistingof hydrogen and hydrocarbon radicals containing less than 7 carbon atoms, with the proviso that at least threeoccurrences-of Bjbe, hydrogen. Typical su bstituted tetrahydropyrimidines of this ,type include:

Z-undecyl, 4-methyltetrahydropyrimidine;

l-ethyl, 2-octyl, 4-dimethyl, 6-cyclohexyltetrahydropyrimidine;

.Z-heptadecyl, 6-methyltetrahydropyrimidine;

Z-abietyl, 4,6-dimethyltetrahydropyrimidine;

2-naphthylmethyl, 1-butyltetrahydropyrimidine;

2cyclohexylethyl, 1,6-dimethyltetrahydropyrimidine;

l-octadecyl, 2-methyltetrahydropyrimidine;

1-oleylamidoethyltetrahydropyrimidine;

l-stearoyloxyethyl, 4-phenyltetrahydropyrimidine;

Z-heptadecenyl, 1-arninopropyltetrahydropyrimidine;

Chloroparatfin alkylation product of l-arninopropyl, 2-

methyltetrahydropyrirnidine;

l-dipropylenediamino, 2-cyc1opentylpropyltetrahydropyrimidine.

Application Serial No. 317,596, filed, October 29, 1952,

now abandoned, Blair, describes as corrosioninhibitors oxyethylated imidazolines; such ascompoundsof the sisting of hydrogen andaliphatic and cycloaliphatic hydro carbon radicals; with the proviso that at least one occurrence of R contains 8 to 32 carbon atoms. examplesofsuchcompounds having corrosion inhibiting properties include .the products obtained by adding from Typical 2 to v20. moles of ethylene oxide 'per mole to the following'imidazolines, as described in said apphcationz 2-undecylimidazoline;

Z-heptadecylimidazoline;

2-oleylimidazoline; I

2-heptadecyl, 4,5-dimethy1imidazoline; 2-heptadecyltetrahydropyrimidine;

Z-hydrdxyethyl, 5-ethyl, l-decyltetrahydropyrimidine; l-aminoethyl, 2-heptadecylimidazoline; l-diethylenediamino, 2-heptadecylimidazoline; l-triethylenetriamino, 2-ethylheptadecylimidazoline; l-aminoethyl, Z-undecylimidazoline; l-diethylenediamino, 2-undecylimidazoline; l-triethylenetriamino, Z-undecylimidazoline; l-aminoethyl, 2-pentadecylimidazoline; l-diethylenediamino, 2-pentadecylimidazoline;

- l-triethylenetriamino, Z-pentadecylimidazoline;

l-aminoethyl, 2-nonylimidazoline;

l-diethylenediamino, 2-nonylimidazoline;

l-triethylenetriamino, Z-nonylimidazoline;

l-aminoethyl, Z-heptadecylenylimidazoline;

l-diethylenediamino, 2-heptadecylenylimidazoline;

l-triethylenetriamino, Z-heptadecylenylimidazoline;

lv-aminoethyl, 2-undecylenylimidazoline;

l-diethylenediamino, 2-undecylenylimidazoline;

l-triethylenetriamino, Z-undecylenylimidazoline;

l-aminoethyl, 2-hydroxyheptadecylenylimidazoline;

l-diethylenediamino, 2 hydroxyheptadecylenylimidazoline;

l-triethylenetriamino, 2 hydroxyheptadecylenylimidazoline;

l-aminoethyl, Z-abietylimidazoline;

l-diethylenediamino, Z-abietylimidazoline;

l-triethylenetriamino, Z-abietylimidazoline;

l-aminoethyl, 2-cyclohexylethylimidazoline;

l-diethylenediamino, 2-cyclohexylethylimidazoline;

l-triethylenetriamino, 2-cyclohexylethylimidazoline;

l-aminoethyl, 2-naphthenylimidazoline;

l-diethylenediamino, Z-naphthenylimidazoline;

l-triethylenetriamino, Z-naphthenylimidazoline;

l-aminopropyl, 2-heptadecyl(methy1*)imidazoline; *in 4 or 5 position l-aminopropylaminopropyl, 2 haptadecyl(methyl*)imidazoline; *in 4 or 5 position l-aminopropyl, 2 heptadecylenyl(methyl*)imidazoline;

*in 4 or 5 position l-aminopropylaminopropyl, 2 heptadecylenyl(methyl*) imidazoline; *in 4 or 5 position l-aminopropyl, 2-undecylenyl(methyl*)imidazoline; *in

-4 or 5 position 1-aminopropylaminopropyl, 2-undecylenyl(methyl*)imidazoline; *in 4 or 5 position l-aminopropyl, 2-abietyl(methyl*)imidazoline; *in 4 or 5 position l-aminopropylaminopropyl, 2 abietyl(methyl*)imidazoline; *in-,4 or 5 position Laminopropyl;2-naphthenyl(methy1*)imidazoline; *in 4 or 5 position l-aminopropylaminopropyl, 2-naphthenyl(methy1*)imidazoline; *in 4 or 5 position Application Serial No. 323,150, filed November 28,

1952, now abandoned, Blair, describes substituted carbonyl.

compounds containing at least two cyclic amidine radicals which are usefully used in preparing compositions of the invention, these being compounds in which the cyclic amidineradical is of the structure wherein R is a hydrocarbon radicalcontaining from 7 t9 ;3.1 carbon atoms; n is the numeral 2,- t0 3 inclusive; R;

is a member of the class consisting of hydrogen atoms and lower alkyl radicals; R is a member of the classthe final compositions, being united through amino nitrogens of the radicals X by at least one member of the:

class consisting of +=Og (::=s; ilJ=NH and radicals. Typical compositions of this type include compositions wherein l-aminoethyl, 2-heptadecyltetrahydropyrimidine is coupled'with urea;

l-aminopropyl, 2-heptadecyltetrahydropyrimidine is coupled with biuret;

l-dipropylenediamino, Z-heptadecyltetrahydropyrimidine is coupled with urea;

l-aminoethyl, 2-undecyltetrahydropyrimidine is coupled with guanidine carbonate;

l-aminopropyl, 2-undecyltetrahydropyrimidine is coupled with biuret;

l-dipropylenediamino, 2-undecyltetrahydropyrimidine is coupled with urea;

l-aminoethyl, 2-decylenyltetrahydropyrimidine is coupled with thiourea;

l-aminopropyl, 2-decylenyltetrahydropyrimidine is coupled with urea; I

l-dipropylenediamino, 2-decylenyltetrahydropyrimidine is coupled with biuret;

l-aminoethyl, Z-heptadecylimidazoline is coupled with urea;

l-diethylenediamino,

with biuret;

l-triethylenetriamino, 2-pentadecylimidazoline is coupled with guanidine carbonate;

l-aminoethyl, Z-undecylenylimidazoline is coupled with thiourea;

l-diethylenediamino, Z-undecylenylimidazoline is coupled with urea;

1-triethylenetriamino, 2-undecylenylimidazoline is coupled with biuret;

l-aminoethyl, 2-hydroxyheptadecylenylimidazoline is coupled with thiourea;

Z-heptadecylimidazoline is coupled l-aminoethyl, 2-cyclohexylethylimidazoline is coupled with urea; l-triethylenetriamino, Z-abietylimidazoline is coupled with thiourea; 1 I l-aminoethyl, Z-naphthenylimidazoline is coupled with urea.

Patent 2,598,213, May 27, 1952, Blair, describes as corrosion inhibitors basic amides of polyamines characterized by the presence of an acyl radical of a carboxy acid having 8 to 32 carbon atoms and at least one basic amino nitrogen atom, that is, an amino radical charac- 7. sure reaction of ethylene dichloride and ammonia; the amide from 300partsof ricinoleic acid andithe same mixture of bases; .the amide from 100parts by weight ofi'olive oil and 100 parts by weight of diethylene triamine; the amide from 310 parts by-wei'ght of the ethyl ester of oleic acid and 286 parts by weight of triethylene tetramine; corresponding amides from purified naphthenic acids and from the carboxy acids derived by the oxidation-oi Pennsylvania crude oil; the amide from 284 parts of stearic acid and 74 parts of 1,2-propylene diamine.

Other effective inhibitors are the higher alkyl diamines such as N-octadecylpropylene diamine, and similar polyamines obtained by treating the monoarnines correspond ing to naturally occurring fatty acids or other monocarboxy detergent-forming acids with acrylonitrile followed by hydrogenation to convert the nitrile group to an amino group. We have found the corrosion inhibiting properties of such compounds are enhanced when they are incorporated in compositions of the present invention.

From the foregoing it will be noted that there are a number of compounds characterizedbythe presence ofat least two nitrogen atoms, at least one of which isbasic, and a hydrocarbon group having 8 to 32 carbon atoms which have corrosion inhibiting properties,- andwhich have their efiectiveness substantially increased by association with an alkylated aromatic sulfonic acid of-the type described above. The effectiveness-of the corrosion inhibitors varies, some being considerablymore effective than others, and so far as we areaware; there will be variation in effectiveness of the compositions of-the invention more or less parallel to the variationsineffectiveness of the corrosion inhibitors per set Webelieve that the most effective of the corrosion inhibitors are the complex cyclic amidines, in particularthe substituted glyoxalidines described in Patent Re. 23,227, and the corn plex amidines described in applications Serial Nos. 227,944, 317,596 and 323,150, together with the amino amide products described in Patent 2,598,213..

We have heretofore referred to the fact that the new compositions of the invention may be used in liquid form, usually with the use of an appropriate solvent such as a mixture of high boiling aromatic hydrocarbons and medium boiling paraffinic hydrocarbons or may be used in stick form with or Without weighting agents. The use of corrosion inhibitors in stick form and in weighted stick form, the purpose. of providing them in such form, and the preparation of products in such form is well known. See, for example, Patents 2,599,384 and 2,599,385, June 3, 1952. The compositions of the present invention may be used as. the corrosion inhibiting constituents of weighted solid stick inhibitors as described'in these patents or of non-weighted solid stick inhibitors.

The invention will be further illustrated by the following specific examples in which typical compositions of the invention are described. In each of them, we have found that the corrosion inhibiting action of the corrosion inhibitor is markedly enhanced by the alkylated aromatic sulfonic acid associated with it. This enhancement is also found with the wide range of inhibitors described above and the examples are, therefore, given purely by way of illustration and not by way of limitation.

Example I tion, 12 lbs. of anhydrous glycolic acid were added slowly. Finallyy IOO-lbss of a -50%- (by wti) solution of am.

monium" diisopropylunaphthalenesulfonatein an -20 mixture of aromatic gas .oil' and isopropyl alcohol were added while stirring. The finished compound was a thin oil.

Example ll 384 lbs. of tall oil and-1461 lbs. of triethylene tetramine were reacted for 2 /2 hrs. at 285 C., as described in Example I. Approximately 41.5 lbs. of water were evolved and condensed from the autoclave. The product consisted of a mixture of monoand diimidazolines with minor proportions of substituted amides of tall oil fatty acids. To lbs. of-this product-were added 191 lbs. of aromatic gas oil and, .whilestirring, 9 lbs. of 66 Baum sulfuric acid; at. such a rate -as to maintain a temperature of less than 100 C. and. above 80 C.

Some heat may be rapplieddf necessarylto maintain this temperature. 100 lbs. of a- 50% (by'wt.) solution of ammonium diisopropyl T naphthalene sulfonate in an 80-20 mixture of commerciah xylene and isopropyl alcohol were added: to the above and the whole stirred until homogeneous;

Examplelll 50 lbs. of ammonium diisobutyl naphthalene sulfonate were substituted for the ammonium diisopropyl naphthalene sulfonateof Example II.

Example 1V 501bs.: of the cyclohexylamine salt ofi diisobutylnaph-- thalene sulfonic acid were substituted for the ammonium diisopropyl. naphthalene. sulfonate of Example 11.

Example V with stirring, lbs. of kerosene, 20 lbSrOf' linoleic acid, and 50 lbs. of cyclohexylammonium.dodecylbenzene sulfonate Example VI A solid-stick type corrosion inhibitor with improved activity was prepared by casting the homogeneous melt resulting from mixing thefollowing ingredients at 100 120 C.:

Corrosion inhibitor of Example V lbs.. 50 Ammonium diisopropyl naphthalene sulfonate ..lbs 10 Microcrystalline wax of 186 F. M.P. ...lbs 40 Oxidized microcrystalline wax of 185 F. M.P. and

60 saponification value lbs 20 The solid product has a density of about 0.93 at 25 C.

Example VII A solid stick type corrosion inhibitor of high density particularly .useful in the treatment of'distillate wells prepared by casting the melt resulting from mixing thoroughlythe following ingredients at'about 120 C.:

Product of Example VI -..lbs 38 Powdered barium sulfate lbs 62 The solid product had a density of about 2.0 and a softening point of about F.

Example VIII The sulfonic acid component of this composition was prepared as follows:

600"'lbs. of a naphthenictype-crude oil (if-22 API gravity were run into a lead lined sulfonating tank, equipped with stirrer, heater coils and drain lines. While stirring and maintaining the oil at 35 C., 300 lbs. of 20% oleum were run into the oil over a period of 3 hrs. The mixture was then stirred for an additional 30 minutes, heated to 90 C. and washed by adding 20 gals. of water. After settling quietly for 4 hrs., the acidic water layer was drawn off and the oil layer neutralized to the methyl orange end point by addition, with stirring, of aqua ammonia (approximately 29% NH;.;).

100 lbs. of this component were mixed with 800 lbs. of the tall oil reaction product of Example II. This mixture was warmed to 80 C. and stirred until homogeneous.

The following is a typical illustration of the enhancement of the corrosion inhibiting action obtained with the compositions ofthe present invention: i

Weighed plates of 1020 steel were rotated in a mixture of 55 ml. of kerosene, and 250 ml. of a brine containing 2% sodium chloride, 0.2% sodium sulfate, 0.4% calcium chloride and 0.4% magnesium chloride hexahydrate. The stirring apparatus was maintained at a temperature of 100 F. in a controlled atmosphere of 0.25 atmosphere of hydrogen sulfide and 0.75 atmosphere of nitrogen. The plates were rotated for a period of 72 hours, after which they were removed, dipped briefly in inhibited HCl to remove ferrous sulfide, washed, dried and weighed to determine loss of metal. Parallel tests were run using no inhibitor, using 160 parts per million of the tall oil reaction product of Example II, using 160 parts per million of the same inhibitor with 16 parts per million of ammonium diisopropyl naphthalene sulfonate, using 160 parts per million of the same inhibitor and 40 parts per million of the same sulfonate, using 160 parts per million of the same inhibitor and 80 parts per million of the same sulfonate, and using no inhibitor but 160 parts per million of the same sulfonate. The average weight loss from tests run in quadruplicate showed 241 mg. with no added agent, 185 mg. with the sulfonate only, 43 mg. with the inhibitor only, 16 mg. with the inhibitor plus 16 parts per million of sulfonate, 20 mg. with the inhibitor plus 40 parts per million of the sulfonate and 14 mg. with the inhibitor plus 80 parts per million of the sulfonate. Similar results were obtained in other laboratory tests using various brine-oil combinations, various corrosive atmospheres, and various combinations of inhibitor and sulfonate.

In another test, carried out under the same conditions, but with a 48 hour test period, the weight loss of the 1020 steel plates was 166 mg. with no added agent, 164 mg. with 40 parts per million of ammonium diisopropyl naphthalene sulfonate, 35 mg. with 40 parts per million of N-aminopropyloctadecylamine, 17 mg. with 40 parts per million of this same amine and 7 parts per million of the sulfonate, 17 mg. with 40 parts per million of the amine and 30 parts per million of the sulfonate and 16 mg. with 40 parts per million of the amine and 40 parts per million of the sulfonate.

The effectiveness of the compositions in the field was shown by the results of a test in a gas distillate well in the Gwinville field in Mississippi. This well produced three million cubic feet of gas, 40 barrels of liquid hydrocarbon and five barrels of salt water a day. Before treatment, water trapped from the flow line at the surface showed an iron content of about 240 parts per million. 2% gallons of the tall oil reaction product of Example 11, dissolved in 7 /2 gallons of hydrocarbon condensate were introduced down the annulus between the casing and the tubing once each week. It flowed down the annulus, became mixed with the produced fluids at the bottom of the hole and was carried up the tubing to the surface by the gas flow. After several weeks of such treatment, the water from the flow line had an iron content of 50 -60 parts per million. 2 /2 gallons of the prod- 10 net of Example II were then substituted for this inhibitor, and used in the same way. After three weeks, the water was found to have an iron content of 10-15 parts per million.

In the foregoing we have referred at length to the inhibitors which are used as being compounds having at least two nitrogen atoms, at least one of which is basic, and at least one hydrocarbon group having 8 to 32 carbon atoms. It is to be understood that these compositions may be used in the form of the free bases, or in partially neutralized form or in completely neutralized form, and such partial or complete neutralization may be by means of an inorganic acid, such as sulfuric acid, or an organic acid, such as acetic acid, gluconic acid, a higher fatty acid or any of the acids which are used for neutralizing basic amino corrosion inhibitors, in accordance with usual practice.

An additional advantage in the use of the new compositions which we have observed is a substantial and unexpected decrease in certain emulsification problems sometimes encountered. Thus, when corrosion inhibitors of the type used in the compositions of the invention are incorporated in hydrocarbon-water systems where the hydrocarbon is relatively pure, i.e., is gasoline, kerosene, distillate, liquefied petroleum gases and the like, as contrasted with crude oil, there is a tendency for oil-in-water emulsions to form. This tendency is greatly reduced, or absent, when the new compositions are used. This is surprising, because the alkylated aromatic sulfonates, while known to resolve water-in-oil emulsions, have found no application as demulsifiers for oil-in-water emulsions.

We claim:

The process of inhibiting corrosion of ferrous metals exposed to corrosive agents normally present in producing oil and gas wells which includes introducing into the well a composition having corrosion inhibiting properties which contains, as an active corrosion inhibiting constituent, a nitrogen-containing agent characterized by having at least 2 nitrogen atoms, at least one of which is basic, and at least one hydrocarbon group having 8 to 32 carbon atoms and which contains, in admixture therewith, as an agent which enhances the corrosion inhibiting activity of the corrosion inhibiting constituent, at least 5% and not over based on the corrosion inhibiting constituent, of an alkylated aromatic sulfonic acid compound selected from the class consisting of alkylated naphthalene sulfonic acid compounds of the formula )n S03 cation in which R is an alkyl radical having 3 to 12 carbon atoms, n is a number from 1 to 3, with the proviso that the total number of carbon atoms present in (R), 1s at least 6, and alkylated benzene sulfonic acid compounds of the formula (R), SO; cation UNITED STATES PATENTS 2,493,483 Francis et a1. Ian. 3, 1950 2,583,399 Wachter Jan. 22, 1952 2,618,608 Schaefier Nov. 18, 1952 2,658,036 Core et a1. Nov. 3, 1953

Claims (1)

1. THE PROCESS OF INHIBITING CORROSION OF FERROUS METALS EXPOSED TO CORROSIVE AGENTS NORMALLY PRESENT IN PRODUCING OIL AND GAS WELLS WHICH INCLUDES INTRODUCING INTO THE WELL A COMPOSITION HAVING CORROSION INHIBITING PROPERTIES WHICH CONTAINS, AS AN ACTIVE CORROSION INHIBITING CONSTITUENT, A NITROGEN-CONTAINING AGENT CHARACTERIZED BY HAVING AT LEAST 2 NITROGEN ATOMS, AT LEAST ONE OF WHICH IS BASIC, AND AT LEAST ONE HYDROCARBON GROUP HAVING 8 TO 32 CARBON ATOMS AND WHICH CONTAINS, IN ADMIXTURE THEREWITH, AS AN AGENT WHICH ENHANCES THE CORRISION INHIBITING ACTIVITY OF THE CORROSION INHIBITING CONSTITUENT, AT LEAST 5% AND NOT OVER 100% BASED ON THE CORROSION INHIBITING CONSTITUENT, OF AN ALKYLATED AROMATIC SULFONIC ACID COMPOUND SELECTED FROM THE CLASS CONSISTING OF ALKYLATED NAPHTHALENE SULFONIC ACID COMPOUNDS OF THE FORMULA