Abstract:
A composition and method for inhibiting the corrosion of steel containing greater than about 9% chromium in the presence of at least one mineral acid, especially at temperatures above 250° F. The composition is made of a corrosion inhibitor selected from phenyl ketone, phenyl ketone with a quaternary salt of a nitrogen-containing heterocyclic aromatic compound, or cinnamaldehyde with a quaternary salt of a nitrogen-containing heterocyclic aromatic compound and an acid soluble metal from antimonium or bismuth.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of application Ser. No. 07/474,232, filed Jan. 30, 1990, now U.S. Pat. No. 5,013,483, application Ser. No. 07/013,603, filed Feb. 12, 1987, now abandoned, and application Ser. No. 06/765,890, filed Aug. 14, 1985, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a new and useful class of corrosion inhibitors, and a process of using them. More particularly, the present invention concerns novel compositions which reduce the attack of aqueous acid solutions on steel, especially steel containing greater than about 9% chromium, and a process of using them. 
     TECHNOLOGY REVIEW 
     In the exploration and recovery of oil from underground fields, it is common to &#34;acidize&#34; both new and producing wells with aqueous solutions of strong acids. As reserves of easily produced hydrocarbons become exhausted, oil and gas companies have been forced to develop deep, hot reservoirs that contain significant quantities of CO 2  and H 2  S. Alloys that contain high concentrations of chromium and nickel have been developed that are much more resistant to the corrosive effects of these acid gases than are carbon alloy tubing steels. Acidizing treatment performed through these high chrome steels, however, present significant problems since the corrosive attack of HCl and HF on these metals is much more difficult to inhibit than is the corrosive attack by these acids on carbon steels. Increasingly, &#34;duplex&#34; chrome steels are being employed in wells that contain high concentrations of H 2  S, because they are much more resistant to hydrogen-induced stress corrosion cracking (HSCC) than are the 13% chromium and nickel and low alloy steels. These metals are called &#34;duplex&#34; because they contain approximately 50/50 percent of ferrite and austenite iron phases. Unfortunately, duplex steels are active metals in hydrochloric acid since there is not enough chromium and nickel to stabilize the passive, protective oxide coatings common to &#34;chrome steels&#34;. 
     Various inhibitors for preventing the attack of acids on high chromium content steels have been proposed. Of the many inhibitors especially designed to prevent acid attack on well casings, very few provide satisfactory protection, especially above about 275° F. 
     U.S. Pat. No. 3,773,465 discloses acid corrosion inhibitors selected from cuprous iodide, acetylenic compounds or nitrogen compounds. Example VIII compares the efficacy of various compounds of iodine and copper, including BiI 3  and Bi(IO 3 ) 3 , each mixed with 2% Halliburton Blend-57 acid corrosion inhibitor. The comparison indicates that cuprous iodide forms an effective inhibited treating acid when added to a treating acid together with acetylenic and nitrogen acid corrosion inhibitors. 
     U.S. Pat. No. 4,493,775 to Coffey et al. discloses a composition for inhibiting corrosion of ferrous metals exposed to acid environments and to H 2  S. The composition is made of 1) a cyclohexylamine or derivatives, salts, or mixtures thereof, 2) per mole of (1), greater than 10 moles of formaldehyde or an amount of paraformaldehyde sufficient to release that amount of formaldehyde, 3) from 3 moles of (1) to an equimolar amount of (2) of acetophenone, derivatives or mixtures thereof, and 4) 0 to 10 wt %, based on the combined weights of (1) to (3), of a C 1  to C 20  aliphatic carboxylic acid and at least one acetylenic alcohol plus unreacted formaldehyde. 
     U.S. Pat. No. 4,498,997 to Walker discloses an acidic solution for acidizing subterranean formations having ferrous metal well bores. The composition is made of an acidic solution, especially of mineral acids, and a corrosion inhibitor made of one or more acetylenic alcohols, a quaternary ammonium compound, an aromatic hydrocarbon having high oil-wetting characteristics, and an antimony (Sb) compound. 
     U.S. Pat. No. 4,552,672 to Walker discloses another acidizing solution for treating subterranean formations which reduces its corrosive effect on ferrous and other metals. The acidizing solution is made of at least one mineral acid and an inhibitor. The inhibitor is made of acetylenic alcohols, quaternary ammonium compounds, an aromatic hydrocarbon having high oil-wetting characteristics, an antimony compound and a stabilizer. The stabilizer can be one of a reactive fluoride-containing compound, compounds having α- or β-hydroxy organic acid functional groups or non-organic acid polyhydroxy compounds. 
     U.S. Pat. No. 4,734,259 to Frenier et al. discloses a corrosion inhibiting composition for use with ferrous metals such as iron and steel and nonferrous metals such as aluminum, zinc and copper. The composition is made of α,β-unsaturated aldehydes and a surfactant. The surfactants may be anionic, cationic, non-ionic, or amphoteric. 
     There remains a need to provide an improved composition for inhibiting stainless steel corrosion caused by mineral acids, and especially at elevated temperatures. 
     SUMMARY OF THE INVENTION 
     The invention provides a composition and method for inhibiting the corrosion of stainless steel in the presence of at least one mineral acid, especially at temperatures above 250° F. The composition comprises an organic inhibitor from the group of phenyl ketone, phenyl ketone with a quaternary salt of a nitrogen-containing heterocyclic aromatic compound, and cynnamaldehyde with a quaternary salt of a nitrogen-containing heterocyclic aromatic compound and an acid-soluble compound from the group consisting of antimony and bismuth (Bi). 
     In a preferred embodiment, the novel composition further comprises formic acid or a formic acid derivative such as formamide or formic ester, when the acid soluble metal is an antimony salt. 
     In another preferred embodiment, when the acid soluble metal is Bi 2  O 3 , the novel composition further includes KI. 
     It is an object of the invention to provide an improved composition for inhibiting stainless steel corrosion caused by mineral acids, and especially by hydrochloric acid alone or in combination with hydrofluoric acid. 
     It is another object of the invention to provide an improved method for inhibiting stainless steel corrosion caused by such mineral acids. 
     It is an advantage of the invention that the improved composition is surprisingly effective in inhibiting the corrosion of stainless steel at elevated temperatures, especially a temperature range from above 250° F. to 475° F. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Various phenyl ketones may be used in the corrosion-inhibiting composition of the present invention. The phenyl ketones may be C 9-20  α-alkenylphenones or hydroxyalkenylphenones and mixtures thereof. Examples of phenyl ketones include: ##STR1## 
     Precursors of alkenylphenones may take a variety of forms. Examples include: ##STR2## 
     The corrosion inhibitors of the present invention may contain more than one precursor of an phenyl ketone. For example, the corrosion inhibitors of the persent invention may include a mixture of precursors including an alpha-hydroxy vinylidene compound and a hydroxy ketone, preferably together with a surfactant. The alpha-hydroxy vinylidene compound has the form ##STR3## where R 1  may be an aryl hydrocarbon or inertly substituted aryl hydrocarbon: m and n must each be less than 5, and the total number of carbons in the compound should be 16 or less. A preferred example of an alpha-hydroxy vinylidene compound is 2-benzoyl-3-hydroxy-1-propene. 
     The hydroxy ketone has the form ##STR4## where R 2  may be an aryl hydrocarbon or inertly substituted aryl hydrocarbon. The value of j must be less than 5, and the compound should contain not more than 16 carbon atoms. A preferred example of a hydroxy ketone is 3-hydroxy-1-phenyl-1-propanone. 
     The nitrogen-containing heterocyclic aromatic quaternary salt may be one of a pyridinium, quinolinium, isoquinolinium, benzoazolinium or benzothiazolinium salts. Specific nitrogen-containing heterocyclic aromatic quaternary salts may be: 
     N-cyclohexylpyridinium bromide 
     N-octylpyridinium bromide, 
     N-nonylpyridinium bromide, 
     N-decylpyridinium bromide, 
     N-dodecylpyridinium bromide, 
     N,N-dodecyldipyridinium dibromide, 
     N-tetradecylpyridinium bromide, 
     N-laurylpyridinium chloride, 
     N-dodecylbenzylpyridinium chloride, 
     N-dodecylquinolinium bromide quinolinium-(1-naphthylenemethyl)chloride, 
     N-naphthylmethyl quinolinium chloride 
     Preferred nitrogen-containing heterocyclic aromatic quaternary salts are naphthylmethyl quinolinium chloride and dodecylpyridinium bromide. 
     The cynnamaldehyde used in the present invention may be substituted or unsubstituted. Examples of substituted cynnamaldehydes useful in the invention are: 
     dicinnamaldehyde, 
     p-hydroxycinnamaldehyde, 
     p-methylcinnamaldehyde, 
     p-ethylcinnamaldehyde, 
     p-methoxycinnamaldehyde, 
     p-dimethylaminocinnamaldehyde, 
     p-diethylaminocinnamaldehyde, 
     p-nitrocinnamaldehyde, 
     o-nitrocinnamaldehyde, 
     o-allyloxycinnamaldehyde, 
     4-(3-propenal)cinnamaldehyde, 
     p-sodium sulfocinnamaldehyde, 
     p-trimethylammoniumcinnamaldehyde sulfate, 
     p-trimethylammoniumcinnamaldehyde o-methylsulfate, 
     p-thiocyanocinnamaldehyde, 
     p-(S-acetyl)thiocinnamaldehyde, 
     p-(S-N,N-dimethylcarbamoylthio)cinnamaldehyde, 
     p-chlorocinnamaldehyde, 
     α-methylcinnamaldehyde, 
     β-methylcinnamaldehyde, 
     α-chlorocinnamaldehyde, 
     α-bromocinnamaldehyde, 
     α-butylcinnamaldehyde, 
     α-amylcinnamaldehyde, 
     α-hexylcinnamaldehyde, 
     α-bromo-p-cyanocinnamaldehyde, 
     α-ethyl-p-methylcinnamaldehyde, 
     p-methyl-α-pentylcinnamaldehyde, 
     By &#34;acid soluble compound of antimony or bismuth&#34; any compound yielding antimony or bismuth anions under acidic conditions is included. Any acid-soluble antimony salt may be used in the present invention. Preferred antimony salts are Sb 2  O 3  and SbCl 3 . Any acid-soluble bismuth compound may be used in the present invention. Examples of soluble bismuth compounds are BiCl 3 , BiI 3 , Bi 2  O 3 , and BiOI. Bi 2  O 3  is preferred. Any source of acid-soluble iodide anion may be used in the present invention. Use of KI is preferred. 
     Formic acid and derivatives of formic acid may advantageously be used in the present invention. The formic acid derivatives may be formamides or formate esters. Formic acid is preferred in the invention. 
     Additionally surfactants and/or solvents may advantageously be used in the present invention. One function of these additives is to keep all the components of the present invention in solution at the temperatures, pressures, lengths of time and pH typical in a subterranean treatment of a formation containing petrochemicals. 
     The relative amounts of the above constituents follows. All percentages given are weight per cents compared to the volume of the acid used in acidizing the formation. From 0.1 to 2% of an organic inhibitor from the group of phenyl ketone, phenyl ketone plus nitrogen-containing heterocyclic aromatic quateruary salts and cynnamaldehyde with a nitrogen-containing, heterocyclic, aromatic quaternary salt can be used with 0.1 to 2% Bi 2  O 3  and 0.1 to 2% KI. Alternatively, 0.1 to 2% of this organic inhibitor can be used with 0.01 to Sb 2  O 3  or SbCl 3  and 0.5 to 10% formic acid. 
    
    
     EXAMPLES 
     In order that those skilled in this technology may better practice the invention, applicants now present illustrations of the present invention, without in any way limiting the scope of the invention. 
     Corrosion tests were conducted in a high pressure autoclave that held 20 4 oz. bottles and was filled with mineral oil to provide hydraulic pressure. One cleaned, 
     2 from a glass hook in weighed steel coupon (25 cm 2 ) was hung the bottle that was filled with 100 mL of HCl solution and sample test inhibitors. The bottle was topped with mineral oil. 
     At the end of testing, the coupons were removed, cleaned in acetone and reweighed. All corrosion rates are expressed as lb/sq.ft. of weight loss for the time period of the test. Duplex steel containing 22-25% Cr and 5% Ni and 13-Cr coupons containing 13% Cr as the major alloying element were tested. After the autoclave was closed, it was pressurized to about 5000 psig and heated to test temperature, and held at that temperature for 6 hours. The bottles were agitated during the test with a &#34;washing machine&#34; action. After the test, the coupons were removed, cleaned and reweighed as above. 
     The following formulations were tested as corrosion inhibitors: 
     FA85 85% formic acid. 
     AFAAF A reaction product of acetophenone, formaldehyde, and an amine; post formulated with acetylenic alcohols, nonionic surfactants and formaldehyde. It is described by U.S. Pat. No. 4,493,775. 
     AFAA A reaction product of acetophenone, formaldehyde, and an amine; post formulated with acetylenic alcohols, and nonionic surfactants. 
     QPK A mixture of quinolinium salts, phenyl ketones and nonionic surfactants. 
     PK A mixture of α-alkenylphenones. 
     NMQCl Naphthylmethylquinolinium chloride. 
     NMBZC Naphthylmethylbenzothiazolium chloride. 
     TCA Trans-cinnamaldehyde. Mixtures of TCA with surfactants are described by U.S. Pat. No. 4,734,259. 
     Octynol 1-octyn-3-ol. 
     DDPB dodecylpyridinium bromide. 
     EXAMPLE 1 
     These tests were run at 300° F. in 15% HCl with duplex steel SM25Cr containing 25% Cr and 5% Ni. 
     
                       TABLE 1______________________________________SM25Cr Tests at 300° F. for 6 Hours in 15% HCl             1st               Removal    Inhibitor             Additive   2d     RateSample   2% Vol   g Sb.sub.2 O.sub.3                        Additive                               lb/sq. ft.______________________________________1         --      0.4        --     0.832        Octynol  0.4        --     0.753        AFAAF    0.04       --     0.164        AFAAF    0.04       2% FA85                               0.0515        QPK      0.04       --     0.0316        QPK      0.4        --     0.014______________________________________ 
    
     Antimony provided protection to the duplex steel in the presence of either the reaction product of acetophenone, formaldehyde and an amine post-formulated with acetylenic alcohol, non-ionic surfactants and formaldehyde (AFAAF) or a mixture of quinolinium salts, phenyl ketone, and nonionic surfactants (QPK), but the protection was improved by the addition of formic acid (FA85). 
     EXAMPLE 2 
     The tests described in Table 2 were run at 350° F. using SM25Cr tubing. 
     
                       TABLE 2______________________________________SM25Cr Tests at 350° F. for 6 Hours in 15% HCl             1st               Removal    Inhibitor             Additive   2d     RateSample   2% Vol   g Sb.sub.2 O.sub.3                        Additive                               lb/sq. ft.______________________________________7        AFAAF    0.2        --     0.428        AFAAF    0.2        2% FA85                               0.0589        QPK      0.4        --     0.2010       QPK      0.2        2% FA85                               0.032______________________________________ 
    
     At this temperature, the combination of formic acid (FA85) with antimony was required for effective inhibition. 
     
                       TABLE 3______________________________________SM25Cr Tests at 300° F. for 6 Hours in 15% HClAll Samples: 1st Additive is 0.48 g Sb.sub.2 O.sub.3                                Removal             2d          3d     RateSample Inhibitor  Additive    Additive                                lb/sq. ft.______________________________________11     0.5 PK     --          --     0.3312     0.5 PK     4% FA85     --      0.04613     0.5 NMQC1  --          --     0.8914     0.5 NMQC1  4% FA85     --     0.9815     0.5 NMBZC  --          --     0.6816     0.5 NMBZC  4% FA85     --     0.9517     0.5 PK     0.5 g NMQC1 --      0.04518     0.5 PK     0.5 g NMQC1 4% FA85                                 0.009419     0.5 PK     0.5 g NMBZC --      0.03020     0.5 PK     0.5 g NMBZC 4% FA85                                 0.009721     TCA        --          --     0.7722     TCA        4% FA85     --     0.6123     TCA        0.5 g NMQC1 --      0.07524     TCA        0.5 g NMQC1 4% FA85                                 0.014______________________________________ 
    
     This experiment shows the organic inhibitors that are operative in the presence of antimony or antimony with formic acid: phenyl ketones, phenyl ketone plus a quaternary salt of nitrogen-containing heterocyclic, aromatic compound, and cinnamaldehyde plus a quaternary salt of nitrogen-containing heterocyclic aromatic compound. All of the commercial inhibitors tested also fall into the above named four categories. 
     EXAMPLE 3 
     Corrosion tests of VS22 steel, a 22% Cr, 5% Ni duplex steel, were in 15% HCl for 8 hours total time. All tests had organic inhibitor and 0.5g SbCl 3 . 
     
                       TABLE 4______________________________________Corrosion of VS22 in 15% HClAll Samples: 1.5% Inhibitor and 0.5 g SbCl.sub.3              Removal Rate     Temperature              lb/sq. ft.Sample Inhibitor           °F. W/O FA85                              W/4% FA85______________________________________25     AFAAF    300        0.31    0.02226     AFAAF    325        0.54    0.02327     AFAAF    350        --      0.45028     AFAA     300        0.26    0.02629     AFAA     325        0.20    0.02330     AFAA     350        --      0.04031     QPK      300        0.03    0.01332     QPK      325        --      0.01333     QPK      350        --      0.016______________________________________ 
    
     These data confirm the findings of Tables 1 to 3. Antimony salts (apparently any salt soluble in HCl) will protect duplex steel in the presence of the specified types of organic inhibitors at 300° F., but the mixture of Sb/formic acid is more effective than the antimony alone, and must be used at the 325°-350° F. range. 
     EXAMPLE 4 
     These tests were run with 13% Cr steel at 350° F. in 15% HCl 1.5% of the inhibitor was used in all cases. 
     
                       TABLE 5______________________________________Corrosion of 13% Cr Steel in 15% HCl with 1.5% Inhibitor                    W/4%   W/SbCl.sub.3                                  W/FA85Sample Inhibitor  Alone   FA85   0.2 g  + Sb______________________________________33    APQCA      0.920   0.870  0.835  0.08134    AFAAF      0.928   0.204  0.820  0.07535    AFAA       0.740   0.295  0.767  0.08436    QPK        0.741   0.155  0.837  0.094______________________________________ 
    
     A synergism is demonstrated for the combination of formic acid and SbCl 3  as compared with the individual aids. At a level of 0.2 g of SbCl 3 , no significant inhibition is found for any of the inhibitors without formic acid. 
     EXAMPLES 6 and 7 
     A number of chemicals and mixtures were tested with antimony and bismuth at temperatures between 300° F.-350° F. in 15% HCl (Table 6) and in 12/3 mud acid (12% HCl and 3% HF, Table 7) for eight hours. 
     
                                           TABLE 6__________________________________________________________________________Corrosion of VS22 in 15% HCl with 1.5% Inhibitor    Temp    SbCl.sub.3 /                SbCl.sub.3 /                        Bi.sub.2 O.sub.3 /                            Bi.sub.2 O.sub.3Sample    Inhibitor    °F.        SbCl.sub.3            FA85                KI  Bi.sub.2 O.sub.3                        FA85                            KI__________________________________________________________________________37  AFAAF    300 0.31            0.022                0.022                    0.37                        0.23                            0.04538  AFAAF    325 0.54            0.02                0.025                    0.68                        0.19                            0.0539  AFAAF    350 --  0.45                0.04                    --  0.73                            0.1140  AFAA 300 0.26            0.026                0.033                    0.66                         0.045                            --41  AFAA 325 0.13            0.023                0.034                    --  --  --42  AFAA 350 --  0.04                0.05                    --  0.33                            0.0843  QPK  300 0.03            0.013                0.02                    0.60                         0.027                            0.02644  QPK  325 --  0.046                0.046                    0.15                         0.010                            0.01845  QPK  350 0.28            0.016                0.039                    --  0.46                            0.12__________________________________________________________________________ 
    
     
                                           TABLE 7__________________________________________________________________________Corrosion of VS22 in 12/3 Mud Acid with 1.5% Inhibitor    Temp    SbCl.sub.3 /                SbCl.sub.3 /                        Bi.sub.2 O.sub.3 /                            Bi.sub.2 O.sub.3Sample    Inhibitor    °F.        SbCl.sub.3            FA85                KI  Bi.sub.2 O.sub.3                        FA85                            KI__________________________________________________________________________46  AFAAF    300 0.045            0.044                0.07                    0.65                        0.56                             0.08347  AFAAF    325 0.13            0.033                0.07                    0.7 0.17                            0.1548  AFAAF    350 --  0.053                --  --  --  --49  AFAA 300 --  0.06                --  --  --  --50  AFAA 325 0.062            0.043                0.11                    --  --  --51  AFAA 350 --  0.07*                --  --  --  --52  QPK  300 0.047            0.047                 0.050                    --  --  --53  QPK  325 --  0.028                 0.038                    0.47                        0.03                            0.1054  QPK  350 --  0.032                 0.045                    --  --  --__________________________________________________________________________ *Unacceptable pitting. 
    
     Table 8 shows a comparative example of an inhibitor based on copper according to U.S. Pat. No. 4,871,024. 
     
                                           TABLE 8__________________________________________________________________________Corrosion of VS22 in HCl or 12/3 Mud Acidwith 1.5% Comparative Cu-based Inhibitor        15% HCl       12/3 Mud Acid    Temp    Cu.sub.2 Cl.sub.2 /                 Cu.sub.2 Cl.sub.2 /                          Cu.sub.2 Cl.sub.2 /                               Cu.sub.2 Cl.sub.2Sample    Inhibitor    F.°        Cu.sub.2 Cl.sub.2            FA85 KI   Cu.sub.2 Cl.sub.2                          FA85 KI__________________________________________________________________________55  AAF  300 0.241            0.15 0.03 0.18                          0.27 0.04556  AFAAF    325 0.60            0.60 0.06 0.41                          0.88 --57  AFAAF    350 --  0.67 0.16 --  --   --58  AFAA 300 0.21            0.11  0.035                      --  --   --59  AFAA 325 --  --   --   --  --   0.4360  AFAA 350 --  0.71 0.09 --  --   --61  QPK  300 0.155             0.062                  0.025                      0.11                          0.18 0.02562  QPK  325 0.21            0.12  0.068                      0.35                          0.09 --63  QPK  350 --  1.1  0.21 --  --   --__________________________________________________________________________ 
    
     The antimony, bismuth, and a comparative prior art inhibitor were tested with phenyl ketone plus a quaternary salt of nitrogen-containing heterocyclic, aromatic compound, the reaction product of acetophenone, formaldahyde, and an amine-post formulated with acetylenic alcohol, and nonionic surfactants (AFAA) or that composition additionally formulated with formaldehyde (AFAAF). 
     As shown in Tables 6-8, at 300° F., many combinations gave acceptably low corrosion rates in 15% HCl. Antimony, bismuth, or the prior art copper when mixed respectively with formic acid or potassium iodide gave acceptable results. At 325° F., the acceptable choices are the same. However, at 350° F., only antimony mixtures or bismuth with KI are acceptable. Regarding Table 7 and that portion of Table 8 pertaining to mud acid, antimony appears to give superior corrosion protection in this agressive acid system. Antimony plus formic acid and a mixture of quinolinium salts, phenyl ketones, and nonionic surfactants gave the lowest corrosion rates at the three temperatures. However, antimony plus potassium iodide also gave acceptable corrosion rates with the mixture of quinolinium sales, phenyl ketones, and nonionic surfactants. 
     It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.