Method for removing contaminants from metal surfaces

Abstract: Materials such as pipe dope, thread lubricants and like contaminants are removed from metal surfaces using a nonaqueous solvent composition comprising a surface active agent for breaking up and dispersing the materials, and D-limonene and a mixture of other terpenes including dipentene for dissolving the materials. The preferred surface active agents are alkyl naphthalene sulfonate diisopropyl amine salts, sodium di-2-ethylhexyl sulfosuccinate and blends of coco-diethanolamide and coco-sulfosuccinate. The composition may also contain glacial acetic acid.

Description: The present invention relates generally to solvent compositions and to a method of removing materials such as pipe dopes and thread lubricants from metal surfaces using the compositions. In the completion and stimulation of oil and gas wells, materials such as pipe dopes, thread lubricants and the like are routinely removed from the surfaces of tubular goods, e.g. strings of threaded tubing and casing disposed in the well bores, prior to performing stimulation treatments, forming gravel packs, etc. If such materials are not removed, they can be carried into producing formations and reduce the production of hydrocarbons therefrom by plugging formation pores and flow channels. For many years solvents including benzene, ethylbenzene, toluene and xylene have been utilized for removing pipe dopes and thread lubricants from tubular goods. Xylene or xylene bottoms are particularly effective in removing commercially available thread lubricants, pipe dopes including those containing metals and other similar materials. However, the use of solvents containing one or more of benzene, ethylbenzene, toluene and xylene has recently been restricted by various regulatory and environment protection agencies. A prior art method of removing pipe dopes using heated xylene bottoms is disclosed in US patent no. 3,437,146. DE-A-3316988 discloses a cleaning agent for cleaning machines, especially for the paper, cardboard; carton and pulp industries. The cleaning agent may include D-limonene, dipentene and additional terpenes and an uncharacterised compatible surfactant. While various environmentally friendly commercial pipe dope and thread lubricant solvents have been developed and utilized heretofore, such solvents suffer from the disadvantage that they are not as effective as the previously used solvents which included benzene, ethylbenzene, toluene and/or xylenes. Thus, there is a need for improved solvent compositions and methods of using the compositions which are as effective or more effective than the previously used solvent compositions and which are environmentally friendly. The invention provides a method of removing contaminant materials such as pipe dopes and thread lubricants from a metal surface, which method comprises contacting the metal surface with a nonaqueous solvent for the contaminants to dissolve them in the composition, said solvent composition comprising a surface active agent for breaking up and dispersing the contaminants, and D-limonene and a mixture of other terpenes predominantly including dipentene for dissolving said contaminants, wherein the surface active agent is an alkyl naphthalene sulfonate diisopropyl amine salt, sodium di-2-ethylhexyl sulfosuccinate, or a blend of coco-diethanolamide and coco-sulfosuccinate. The environmentally friendly nonaqueous solvent compositions of the present invention are particularly effective in removing materials such as commercial thread lubricants, metal-containing pipe dopes and metal-free pipe dopes. As mentioned, it is essential that such materials be removed from the surfaces of tubing and casing disposed in a well bore prior to performing producing formation stimulation treatments, forming gravel packs in the well or performing any other treatment or procedure whereby the materials may be carried into producing formations. If such materials are not removed, they can be carried into producing formations or gravel packs whereby hydrocarbon flow pores and channels are plugged. The environmentally friendly nonaqueous solvent compositions of the present invention are basically comprised of surface active agent as defined in claim 1 for breaking up and dispersing the materials to be removed by the solvent composition, D-limonene and a mixture of other terpenes predominantly including dipentene for dissolving the materials. Terpenes are unsaturated hydrocarbons having the formula C 10 H 16 which may be either acyclic or cyclic with one or more benzenoid groups. They are highly effective solvents and are not harmful to the environment. A particularly suitable mixture of terpenes for use in accordance with the present invention predominantly includes dipentene and D-limonene. Such a mixture which is presently preferred is comprised of a commercial mixture of dipentene and other terpenes from a paper pulping process and commercial D-limonene. The commercial mixture of dipentene and other terpenes from a paper pulping process is commercially available from the Halliburton Company of Duncan, Oklahoma, under the trade designation "PARAGON 1 E + ™" and has the following composition. Component Volume % dipentene 25 α-pinene 17 1,4-cineole 16 1,8-cineole 11 terpinolene 10 camphene 8 α-terpinene 7 γ-terpinene 5 para-cymene 1 100 The commercial D-limonene is available, for example, from the Florida Chemical Company of Lake Alfred, Florida. The surfactants are selected from the group consisting of an alkyl naphthalene sulfonate diisopropyl amine salt, sodium di-2-ethylhexyl sulfosuccinate and a blend of coco-diethanolamide and coco-sulfosuccinate. The alkyl naphthalene sulfonate diisopropyl amine salt surface active agent is commercially available, for example, from Champion Technologies, Inc. of Houston, Texas. The sodium di-2-ethylhexyl sulfosuccinate surface active agent is commercially available from Witco Chemical Company of Houston, Texas. The blend of coco-diethanolamide and coco-sulfosuccinate surface active agent is commercially available from Mona Chemical Company of Paterson, New Jersey. A preferred nonaqueous solvent composition of the present invention which is a liquid blend is comprised of one of the surface active agents described above present in an amount in the range of from about 5% to about 25% by volume of the composition, D-limonene present in an amount in the range of from about 5% to about 90% by volume of the composition, and a mixture of other terpenes predominantly including dipentene present in an amount in the range of from about 5% to about 90% by volume of the composition. The most preferred liquid blend solvent composition is comprised of an alkyl naphthalene sulfonate diisopropyl amine salt surface active agent present in an amount of about 15% by volume of the composition, D-limonene present in an amount of about 35% by volume of the composition, and a mixture of other terpenes predominantly including dipentene present in an amount of about 50% by volume of the composition. The nonaqueous solvent compositions of this invention preferably include glacial acetic acid to react with metals and other reactive components in the pipe dopes and other materials to be removed and facilitate the dispersal of the materials. When glacial acetic acid is included, the solvent composition is preferably formed into an emulsion which prevents the acid from spending too quickly. A preferred composition including acetic acid is comprised of a surface active agent of the type described above present in an amount in the range of from about 5% to about 25% by volume of the composition, D-limonene present in an amount in the range of from about 5% to about 90% by volume of the composition, a mixture of other terpenes predominantly including dipentene present in an amount in the range of from about 5% to about 90% by volume of the composition, and glacial acetic acid present in an amount in the range of from about 5% to about 25% by volume of the composition. A particularly preferred emulsified nonaqueous solvent composition containing glacial acetic acid of this invention is comprised of a blend of coco-diethanolamide and cocosulfosuccinate present in an amount of about 20% by volume of the composition, D-limonene present in an amount of about 10% by volume of the composition, a mixture of other terpenes predominantly including dipentene present in an amount of about 60% by volume of the composition, and glacial acetic acid present in an amount of about 10% by volume of the compositions. It has been found that a particular mixing order must be followed if a stable emulsion of the composition of the present invention is to be formed. Initially, the D-limonene and mixture of terpenes are admixed. The surface active agent then is added to the mixture followed by the glacial acetic acid. This method of making the emulsions forms a further aspect of the present invention. Failure to admix the constituents in the above order results in an unstable mixture that rapidly separates. The unstable mixture fails to achieve the high degree of pipe dope removal effected by the stable emulsion prepared in accordance with the present invention. The contaminated surfaces having materials such as pipe dopes, thread lubricants and the like thereon, are contacted with the nonaqueous solvent composition for a time period sufficient for the materials to be dissolved in the composition. In removing materials such as commercial thread lubricants and pipe dopes with or without metal particles from the surfaces of tubing and casing disposed in a well bore, the solvent composition can be circulated down the tubing and up the annulus between the tubing and the casing for a time period sufficient to remove the materials from the tubing and casing surfaces. During such circulation, small quantities of formation fluids, including water, may become admixed with the solvent, however such compositions remain substantially nonaqueous during the time period over which it removes the lubricants or pipe dopes. Other techniques can also be utilized such as pumping the nonaqueous solvent composition into the tubing and annulus, and after the required time period, displacing the solvent composition containing dissolved materials to the surface with produced fluids. Generally, as is shown by the Examples which follow, the nonaqueous solvent compositions of this invention are caused to contact surfaces containing the materials to be removed for time periods in the range of from about 5 minutes to about 20 minutes so that substantially all of the materials are dissolved in the solvent compositions. As mentioned above, depending upon the particular materials to be removed, either a liquid blend nonaqueous solvent composition which does not contain acetic acid is utilized or a stable emulsified nonaqueous solvent composition containing acetic acid is utilized. Generally, the emulsified composition with acetic acid is utilized where the materials to be removed contain acid reactive materials such as metal particles and the like. In order to further illustrate the method of this invention, the following Examples are given, some of which also describe compositions which are not in accordance with the invention but which are given for comparison. It will be noted that none of the compositions of the invention contain any water. Example 1 Ten surface active agents were screened for use in solvent compositions for the removal of pipe dopes, thread lubricants and the like from surfaces. Because the solvents utilized in well bores would be contacted by brine, suitable surfactants were deemed to be those that were compatible with brine, i.e., did not form precipitates when contacted by brine. The screening of the surfactants was performed by adding 10% by volume of each surfactant tested to 90% by volume API brine in a 0.12 l (4 oz) jar, sealing the jar and shaking it by hand for 1 minute. Descriptions of the surface active agents tested, and the results of the brine compatibility tests are set forth in Table I below. Surface Active Agent Descriptions and Brine Compatibility Surface Active Agent Chemical Description Trade Designation And Commercial Source Brine Compatibility Alkyl Naphthalene Sulfonate Diisopropyl Amine Salt "P-1112™" Champion Technologies, Inc. of Houston, Texas Miscible, no precipitate. Went from turbid to clear upon standing. Sodium Di-2-ethylhexyl Sulfosuccinate "EMCOL 4500™" Witco Chem. Corp. of Houston, Texas Miscible, no precipitate. Went from turbid to clear upon standing. Blend of coco-diethanolamide and coco-sulfosuccinate "MONAMULSE DL-1273™" Mona Industries, Inc. of Paterson, N.J. Miscible, no precipitate. Went from turbid to clear upon standing. Alkylaryl Sulfonic Acid "WITCOLATE D51-29™" Witco Chem. Corp. of Houston, Texas Milky, precipitate formed. Phosphate Ester of Alkylaryl Ethoxylate "EMPHOS CS-1361™" Witco Chem. Corp. of Houston, Texas Milky, precipitate formed. Polypropoxy Quaternary Ammonium Chloride "EMCOL CC-36™" Witco Chem. Corp. of Houston, Texas Milky, precipitate formed. Alkanolamide "WITCAMIDE 511™" Witco Chem. Corp. of Houston, Texas Milky, precipitate formed. Alkanolamide "WITCAMIDE 5138™" Witco Chem. Corp. of Houston, Texas Milky, precipitate formed. Blend of anionic and nonionic surfactants "MONAMULSE 653C™" Mona Indus., Inc. of Paterson, N.J. Milky, precipitate formed. Mixture of mono and diphosphate esters "MONAFAX 785™" Mona Indus., Inc. of Paterson, N.J. Milky, precipitate formed. As shown in Table I only three surfactants passed the API brine compatibility tests, namely an alkyl naphthalene sulfonate diisopropyl amine salt, sodium di-2-ethylhexyl sulfosuccinate and a blend of coco-diethanolamide and coco-sulfosuccinate. Example 2 Thirty-one different solvent compositions, identified in Table II below, were obtained and/or prepared for evaluation. The first ten solvents, i.e., S1 through S10, were commercially available products. The last twenty-one solvents, i.e., S11 through S31, were laboratory prepared blends or emulsions comprised of the components in the amounts shown in Table II. The emulsion were prepared utilizing the mixing order previously described. Samples of solvents S11 through S31 were tested for brine compatibility utilizing the procedure set forth in Example 1 above. The results of the compatibility tests are given in Table II. Six commercially available pipe dopes described in Table III below were obtained for testing. As shown, the pipe dopes included two metal containing pipe dopes, two conventionally used proprietary mixture pipe dopes, and two metal free, environmentally safe pipe dopes. Pipe Dopes Tested Pipe Dope No. Pipe Dope Description Trade Designation And Commercial Source PD-1 Proprietary Mixture "LIQUID-O-RING 300™" Oil Center Research, Inc. of Lafayette, LA. PD-2 Mixture of grease, oil, lead, zinc, copper, graphite, talc and lime API MODIFIED Pipe Dope RSR Corporation of Dallas, TX. PD-3 Proprietary Mixture "LUBON 404™" Oil Center Research, Inc. of Lafayette, LA. PD-4 Mixture of oil, soap, lead and copper "KOPR-KOTE" Jet-Lube, Inc. of Houston, TX PD-5 Mixture of lithium, 12-OH stearate base grease, oil, talc, synthetic and amorphous graphite and polytetrafluoroethylene ("TEFLON®"). "BESTOLIFE METAL FREE™" RSR Corporation of Dallas, TX. PD-6 Environmentally safe, metal free, petroleum base grease. "LOS-MODIFIED™" LUB-O-SEAL Co., Inc. of Houston, TX. Example 3 The various solvent compositions set forth in Table II were tested to determine their effectiveness in removing the pipe dopes identified in Table III. The test procedure used was as follows. A volume of 200 milliliters of the solvent composition to be tested was placed in a 300 milliliter beaker. A magnetic stirring bar was inserted, and the beaker was placed on a magnetic stirrer. Coupons cut from N-80 steel having dimensions of 15.2 cm (6") (length) x 5.1 cm (2") (width) x 0.318 cm (1/8") (thickness) were utilized in the tests. A coupon was first weighed, and then a small amount of the pipe dope to be removed was smeared on the coupon on one side and at one end thereof. The coupon was reweighed to determine the exact weight of the pipe dope. Approximately 3 grams of pipe dope were used in each test. The coupon was then suspended in the solvent composition in the 300 milliliter beaker with the end containing the pipe dope submerged in the solvent composition. The solvent composition was agitated by the magnetic stirrer for 5 minutes at ambient conditions. The coupon was then removed from the beaker and gently rinsed with distilled water. Excess water was blotted with a paper towel, and the coupon was dried in an oven at 93.3°C (200°F) for 15 minutes. After removing the coupon from the oven, it was allowed to cool to ambient temperature. A final weight was then determined and the percentage of pipe dope removed was calculated. If less than 100% of the pipe dope was removed, the test was repeated up to a maximum of 20 minutes in 5 minute intervals using the same coupon and the remaining pipe dope until the 20 minutes had expired or 100% of the pipe dope had been removed. The results of the tests are set forth in Tables IV through IX below. Percent Of Pipe Dope PD-1 Removed By Test Solvent Compositions ------------------------------- Percent Removed ------------------------------ Solution 5 Minutes 10 Minutes 15 Minutes 20 Minutes S1 37.9 79.3 100 - S2 27.2 56 79.5 90.1 S3 37.6 69.1 87.5 91.3 S4 32.7 57.8 72.1 74.6 S5 1.3 5.3 6.6 9.7 S6 10.6 29.6 41.2 51.2 S7 11.5 35.1 49.8 58.4 S8 35.1 62.7 79.4 84.2 S9 25.6 48.2 61.5 70.1 S10 22.3 38.4 50.2 57.1 S11 45.5 63.2 79.0 92.8 S12 31.0 59.0 72.0 87.7 S13 29.3 55.6 78.6 94.4 S14 16.1 33.9 50.3 71.9 S15 14.6 29.4 44.9 60.9 S16 23.6 47.3 70.3 86.9 S17 57.4 79.3 94.4 97.7 S18 67.4 92.9 98.7 100 S19 56.5 66.3 72.9 75.1 S20 70.0 98.4 100 - S21 80.6 93.9 100 - S22 70.3 88.1 94.1 95.7 S23 67.4 93.8 100 - S24 68.2 98.7 100 - S25 61.0 85.6 98.1 99.4 S26 29.4 58.4 81.3 92.3 S27 25.6 51.9 80.7 96.2 S28 31.7 62.4 80.1 89.9 S29 41.2 74.4 92.7 97.0 S30 42.5 80.2 95.9 96.2 S31 42.0 86.9 98.7 99,0 From Table IV it can be seen that none of the ten commercially available solutions S1 through S10 were effective in removing at least 90% of the "LIQUID-O-RING 300™" Pipe Dope in the first ten minutes. Solvent compositions S18, S20, S21, S23 and S24 removed at least 90% of the "LIQUID-O-RING 300™" within 10 minutes. Blend S24 was the most effective, removing 98.7% of the "LIQUID-O-RING 300™" in 10 minutes. Percent Of Pipe Dope PD-2 Removed By Test Solvent Compositions ------------------------------ Percent Removed ------------------------------ Solution 5 Minutes 10 Minutes 15 Minutes 20 Minutes S1 96.6 99.0 100 - S2 59.3 80.2 94.0 100 S3 64.0 82.6 84.6 88.1 S4 80.7 99.3 100 - S5 0.0 0.0 0.0 1.3 S6 53.3 70.7 83.3 92.1 S7 36.9 76.5 79.4 87.3 S8 26.2 43.7 50.0 54.3 S9 - - - - S10 - - - - S11 59.4 84.6 95.2 98.2 S12 84.7 94.8 96.6 96.6 S13 68.4 83.6 89.5 95.4 S14 24.7 46.7 70.1 83.2 S15 30.6 58.6 68.4 93.8 S16 40.1 65.2 85.8 96.4 S17 40.1 47.9 53.8 56.0 S18 39.0 58.0 69.8 74.8 S19 40.3 53.6 60.7 62.7 S20 50.3 72.3 82.9 87.1 S21 40.8 65.0 75.2 83.0 S22 54.8 73.8 81.6 85.9 S23 47.2 75.6 93.5 98.4 S24 32.4 54.3 82.9 96.8 S25 52.4 81.6 96.1 96.4 S26 45.0 78.0 88.1 93.0 S27 39.9 80.4 96.1 96.8 S28 59.2 89.2 96.7 99.0 S29 55.9 93.5 99.7 100 S30 59.9 97.4 100 - S31 68.3 92.7 97.5 97.5 As shown in Table V above, reagent grade xylene, solvent composition S1, was effective in removing at least 90% of the API MODIFIED pipe dope in 5 minutes. Commercially available D-Limonene, S4, was effective in removing at least 90% of the pipe dope in 10 minutes. Solvent compositions S12, S29, S30 and S31 all removed at least 90% of the API MODIFIED Pipe Dope within 10 minutes. Percent Of Pipe Dope PD-3 Removed By Test Solvent Compositions ------------------------------- Percent Removed ------------------------------- Solution 5 Minutes 10 Minutes 15 Minutes 20 Minutes S1 51.9 89.7 98.6 100 S2 26.7 44.0 57.7 74.9 S3 24.6 50.2 71.7 88.5 S4 39.9 74.1 92.0 100 S5 2.6 3.3 4.3 6.9 S6 14.0 27.6 37.5 54.0 S7 12.4 22.4 27.6 40.5 S8 - - - - S9 30.5 57.8 76.3 90.6 S10 24.2 42.1 56.3 70.2 S11 24.0 44.0 63.7 78.3 S12 25.5 40.9 59.2 76.8 S13 22.3 43.0 65.1 82.9 S14 11.3 26.2 38.2 56.0 S15 7.6 20.7 35.0 49.0 S16 17.8 29.1 44.3 59.2 S17 13.0 21.4 27.9 35.6 S18 19.5 36.0 49.7 62.0 S19 15.4 23.6 28.5 34.8 S20 21.2 36.8 45.3 56.7 S21 28.4 48.3 62.0 74.8 S22 22.0 40.9 59.8 74.2 S23 15.8 32.2 46.4 61.5 S24 18.2 36.2 51.1 63.2 S25 22.2 39.9 58.5 75.8 S26 25.1 52.4 75.9 88.6 S27 23.4 48.4 73.0 85.5 S28 25.8 53.3 74.5 89.4 S29 30.2 56.9 81.0 92.6 S30 22.9 39.1 54.6 71.5 S31 47.9 84.1 98.1 98.1 As shown in Table VI, reagent grade xylene, S1, and commercial D-Limonene, S4, were effective in removing at least 90% of "LUBON 404™" thread lubricant in 15 minutes. Solvent composition S31 was effective in removing at least 90% of the "LUBON 404™" after 15 minutes and solvent composition S29 removed at least 90% of the lubricant after 20 minutes. Percent Of Pipe Dope PD-4 Removed By Test Solvent Compositions ------------------------------- Percent Removed ------------------------------- Solution 5 Minutes 10 Minutes 15 Minutes 20 Minutes S17 28.7 59.6 77.1 86.3 S18 43.7 79.3 88.0 94.3 S19 22.0 44.1 51.8 63.9 S23 55.3 81.9 90.9 92.6 S24 70.3 92.8 98.7 100 S25 60.3 84.9 92.3 95.5 S26 36.8 66.2 83.4 85.8 S27 46.3 72.5 87.2 89.8 S28 47.9 47.9 88.9 92.8 S29 51.1 77.0 90.9 96.4 S30 50.8 85.2 96.5 99.7 S31 53.9 78.7 92.6 96.8 As indicated in Table VII above, solvent composition S24 was effective in removing at least 90% of the "KOPR-KOTE™" Pipe Dope after 10 minutes. Solvent compositions S23, S25, S29, S30 and S31 were all effective in removing at least 90% of the pipe dope after 15 minutes. Solvent compositions S18 and S28 were effective in removing at least 90% after 20 minutes. The most consistent solvent compositions in removing the metal containing pipe dopes, i.e., API MODIFIED Pipe Dope (Table V) and "KOPR-KOTE™" Pipe Dope (Table VII) were solvent compositions S24 and S31. Percent Of Pipe Dope PD-5 Removed By Test Solvent Compositions ------------------------------ Percent Removed ------------------------------- Solution 5 Minutes 10 Minutes 15 Minutes 20 Minutes S1 40.0 78.9 91.4 96.8 S2 28.2 58.0 80.1 91.4 S3 48.7 79.6 92.7 99.4 S4 48.5 81.9 91.8 99.0 S5 2.2 6.3 8.8 12.3 S6 9.1 24.9 29.1 36.6 S7 3.9 15.6 20.1 26.6 S23 51.4 80.1 89.3 93.7 S24 46.7 71.4 85.2 89.1 S25 34.8 69.2 85.6 92.5 S29 29.6 58.4 81.2 90.3 S30 37.3 65.3 81.9 92.0 S31 61.4 82.2 91.1 97.4 As shown in Table VIII above, commercially available pipe dope solutions S1 through S7 were tested as well as solvent compositions S23-S31 in removing "BESTOLIFE METAL FREE™" Pipe Dope. Reagent Grade Xylene, S1, "PARAGON 1 E + ", S3, and commercially available D-Limonene, S4, were all effective in removing at least 90% of the "BESTOLIFE" Pipe Dope after 15 minutes. Solvent composition S31 was effective in removing at least 90% after 15 minutes, while solvent compositions S23, S25, S29 and S30 all removed at least 90% of the pipe dope after 20 minutes. Percent Of Pipe Dope PD-6 Removed By Test Solvent Compositions -------------------------------Percent Removed------------------------------ Solution 5 Minutes 10 Minutes 15 Minutes 20 Minutes S1 81.8 92.7 99.7 100 S2 38.9 55.5 71.3 81.2 S3 19.8 26.4 38.9 43.3 S4 74.9 84.0 94.8 97.7 S5 2.6 4.8 10.3 13.8 S6 14.6 21.6 33.2 35.2 S7 34.4 67.9 79.7 87.9 S23 31.2 46.1 62.0 74.4 S24 40.3 63.2 81.9 90.7 S25 68.9 83.4 95.4 97.4 S29 65.1 82.2 87.5 93.4 S30 61.3 76.7 86.7 92.3 S31 64.6 80.0 85.6 88.5 As shown in Table IX, Reagent Grade Xylene, S1, was effective in removing at least 90% of the environmentally safe, metal free "LOS-MODIFIED™" Pipe Dope after 10 minutes. Commercially available D-Limonene, S4, was effective in removing at least 90% of the pipe dope after 15 minutes. Solvent composition S25 was effective in removing at least 90% of the pipe dope after 15 minutes while blends S24, S29 and S30 were effective in removing at least 90% after 20 minutes. From the various test results set forth above, it can be seen that the most effective solvent compositions overall were emulsions S23, S24 and S25 and liquid blends S29, S30 and S31 of the present invention. The most successful solvent compositions were emulsions S23, S24 and S25 of the present invention wherein the external phase of the emulsion was the terpene solvent mixture and the internal phase was glacial acetic acid. The data clearly demonstrates that not all terpenes or mixtures containing terpenes function in an equivalent manner to the nonaqueous solvent composition of the present invention. All six of the solvent compositions of the present invention, i.e., emulsions S23, S24 and S25 and liquid blends S29, S30 and S31 were subjected to thermal stability tests at 93.3°C (200°F) in a hot water bath for 6 hours. There was no separation or layering out of the various components during this time period and no change in appearance was observed. EXAMPLE 4 To demonstrate the importance of the mixing order to the formation of a stable emulsion, the following test was performed. Five samples were prepared in which the mixing order of the constituents were varied. The solvent constituents, identified as "Solvent" comprised D-Limonene and the mixture of terpenes described in solvent composition S24 of Example 3 in the amounts set forth for such compostition. The surface active agent was a blend of coco-diethanolamide and coco-sulfosuccinate, identified as "Surfactant" and the acid was glacial acetic acid and was identified as "Acid" which were also present in the same amount as S24 of Example 3. The mixing order was as follows: Sample 1 : Solvent + Acid + Surfactant Sample 2 : Surfactant + Acid + Solvent Sample 3 : Acid + Solvent + Surfactant Sample 4 : Acid + Surfactant + Solvent Sample 5 : Solvent + Surfactant + Acid The samples were placed in a hot water bath maintained at 65.5°C (150°F) Samples 1-4 each visibly separated within less than four hours. Sample 5 prepared in accordance with the present invention showed no visible signs of separation. Thus it is apparent that Samples 1-4 did not comprise a stable emulsion.

Claims: A method of removing contaminant materials from a metal surface, which method comprises contacting the metal surface with a nonaqueous solvent for the contaminants to dissolve them in the composition, said solvent composition comprising a surface active agent for breaking up and dispersing the contaminants, and D-limonene and a mixture of other terpenes predominantly including dipentene for dissolving said contaminants, wherein the surface active agent is an alkyl naphthalene sulfonate diisopropyl amine salt, sodium di-2-ethylhexyl sulfosuccinate, or a blend of coco-diethanolamide and coco-sulfosuccinate. A method according to claim 1, wherein the mixture of other terpenes comprises the following, each expressed as by volume of said mixture: 25% dipentene; 17% α-pinene; 16% 1,4-cineole; 11% 1, 8-cineole; 10% terpinolene; 8% camphene; 7% α-terpinene; 5% γ-terpinene; and 1% para-cymene. A method according to claim 1 or 2, wherein the composition further comprises, by volume of said composition: 5% to 25% of the surface active agent; 5% to 90% of the D-limonene; and 5% to 90% of the said mixture of other terpenes including dipentene. A method according to any preceding claim, wherein the nonaqueous solvent composition further comprises glacial acetic acid for reacting with said materials, and said composition is formed into an emulsion by admixing said D-limonene and said mixture of terpenes with said surface active agent prior to contact with said glacial acetic acid. A method according to claim 4, wherein the glacial acetic acid is present in an amount of from 5% to 25% by volume of said composition. A method according to claim 4 or 5, wherein the components are present, in an amount by volume of the composition of: 20% of the surface active agent where the surface active agent is a blend of coco-diethanolamide and coco-sulfosuccinate; 10% of D-limonene; 60% of said mixture of other terpenes including dipentene; and 10% of said glacial acetic. A method according to claim 1, 2 or 3, wherein the surface active agent is an alkyl napthalene sulfonate diisopropyl amine salt present in an amount of 15% by volume of said composition, said D-limonene is present in an amount of 35% by volume of said composition and said mixture of other terpenes including dipentene is present in an amount of 50% by volume of said composition.

Inventors: FORD WILLIAM G F, GARDNER TOMMY R, FORD, WILLIAM G.F., GARDNER, TOMMY R.
Applicants: HALLIBURTON ENERGY SERV INC, HALLIBURTON ENERGY SERVICES, INC.
Application year: 1995
Main classification: C23G5
IPC codes: C11D3, C23G5