Use Of A Composition Containing At Least One Biodegradable Sugar-Amide-Compound In Combination With At Least One Sulfur-Based Synergist For Corrosion Inhibition Of A Metallic Equipment In Oilfield Applications

Abstract

In this invention the use of glucamides in combination with at least one sulfur-based synergist chosen from the group of thiols, thioethers, thiosulfates, thioglycolic acids, thiourea or derivatives thereof in a formulation for corrosion inhibition in the gas and oil industry is described.

Claims

1. A composition comprising a) at least one compound according to formula (1) ##STR00005## wherein Ra is a C.sub.5 to C.sub.29 linear, branched, saturated or unsaturated aliphatic hydrocarbon group, Rb is a C.sub.1 to C.sub.23 linear, branched, saturated or unsaturated aliphatic hydrocarbon group, or a compound obtainable from formula 1 by eliminating one mole of water from the polyhydroxy group, thereby forming a cyclic ether, and b) at least one sulfur synergist selected from the group consisting of b1) a compound according to formula (5)
R.sup.1SR.sup.2(5) wherein R.sup.1 and R.sup.2 are independently hydrogen, C.sub.1 to C.sub.18 alkyl, C.sub.2 to C.sub.18 alkenyl or a C.sub.7 to C.sub.18 alkyl aromatic group, and wherein R.sup.1 and R.sup.2 may contain oxygen or nitrogen atoms, or may be substituted with a carboxylic acid group or an amide group, with the proviso that R.sup.1 and R.sup.2 are not both hydrogen b2) a metal or ammonium thiosulfate salt, and b3) a compound according to formula (6)
S=C(NHR.sup.5)(NHR.sup.6)(6) wherein R.sup.5 and/or R.sup.6 are H, C.sub.1 to C.sub.10 alkyl, C.sub.2 to C.sub.10 alkenyl or C.sub.5 to C.sub.9 aryl groups or mixtures thereof, as a corrosion inhibitor for metallic oilfield equipment.

2.-14. (canceled)

15. A process for preventing corrosion on metallic oilfield equipment, comprising the step of adding a composition comprising a) at least one compound according to formula (1) ##STR00006## wherein Ra is a C.sub.5 to C.sub.29 linear, branched, saturated or unsaturated aliphatic hydrocarbon group, Rb is a C.sub.1 to C.sub.23 linear, branched, saturated or unsaturated aliphatic hydrocarbon group, or a compound obtainable from formula 1 by eliminating one mole of water from the polyhydroxy group, thereby forming a cyclic ether, and b) at least one sulfur synergist selected from the group consisting of b1) a compound according to formula (5)
R.sup.1SR.sup.2(5) wherein R.sup.1 and R.sup.2 are independently hydrogen, C.sub.1 to C.sub.18 alkyl, C.sub.2 to C.sub.18 alkenyl or a C.sub.7 to C.sub.18 alkyl aromatic group, and wherein R.sup.1 and R.sup.2 may contain oxygen or nitrogen atoms, or may be substituted with a carboxylic acid group or an amide group, with the proviso that R.sup.1 and R.sup.2 are not both hydrogen b2) a metal or ammonium thiosulfate salt, and b3) a compound according to formula (6)
S=C(NHR.sup.5)(NHR.sup.6)(6) wherein R.sup.5 and/or R.sup.6 are H, C.sub.1 to C.sub.10 alkyl, C.sub.2 to C.sub.10 alkenyl or C.sub.5 to C.sub.9 aryl groups or mixtures thereof, to a fluid produced from an oil or gas well, the fluid being in contact with the metallic oilfield equipment.

16. The process according to claim 15, wherein component a) is obtained from the compound of formula 1 by elimination of one mole of water from its polyhydroxy alkyl chain, and is a compound according to the formulae (2) to (4) ##STR00007## wherein Ra is a C.sub.5 to C.sub.29 linear, branched, saturated or unsaturated aliphatic hydrocarbon group, Rb is a C.sub.1 to C.sub.23 linear, branched, saturated or unsaturated aliphatic hydrocarbon group.

17. The process according to claim 15, in which Ra is an alkyl or alkenyl group with 7 to 21 carbon atoms.

18. The process according to claim 15, in which Rb is methyl.

19. The process according to claim 15, in which the sulfur synergist is represented by the formula R.sup.1SR.sup.2 wherein R.sup.1 is hydrogen, and R.sup.2 is an alkyl group with 1 to 12 carbon atoms that may contain oxygen or nitrogen atoms.

20. The process according to claim 15, in which the sulfur synergist is represented by the formula R.sup.1SR.sup.2 wherein R.sup.1 is an alkyl group having 1 to 4 carbon atoms, that may contain oxygen or nitrogen atoms and R.sup.2 is an alkyl group having 2 to 26 carbon atoms, that may contain oxygen or nitrogen atoms

21. The process according to claim 15, wherein one of R.sup.1 and R.sup.2 comprises a carboxylic acid group.

22. The process according to claim 21, in which the sulfur synergist is represented by the formula M(HSCH.sub.2COO).sub.x wherein a) x=1 and M is selected from the group consisting of Li, Na, K, Ag, Cu or NH.sub.4, and tertiary amines with alkyl, alkylene or alkoxyalkyl side groups, that may also be cyclic and may contain the heteroatoms O or N; b) x=2 and M is selected from the group consisting of Mg, Ca, Sr, Cu, Zn, Pb or Fe and tertiary amines with alkyl, alkylene or alkoxyalkyl side groups, that may also be cyclic and may contain the heteroatoms O or N; c) x=3 and M is selected from the group consisting of Al, Bi or Fe.

23. The process according to claim 15, in which the sulfur synergist is, represented by the formula M.sub.x(S.sub.2O.sub.3) wherein x=2 and y=1 and M=Li, Na, K, Ag, Cu or NH.sub.4; or x=1 and y=1 and M=Mg, Ca, Sr, Cu, Zn, Pb or Fe; or x=2 and y=3 and M=Al, Bi or Fe.

24. The process according to claim 15, in which the sulfur synergist is a thiourea, represented by the formula
S=C(NHR.sup.5)(NHR.sup.6)(6) wherein R.sup.5 and/or R.sup.6 are H, C.sub.1 to C.sub.10 alkyl, C.sub.2 to C.sub.10 alkenyl or C.sub.5 to C.sub.9 aryl groups or mixtures thereof.

25. The process according to claim 15, wherein the concentration of component a) is from 0.1 to 30 ppm.

26. The process according to claim 15, wherein the concentration of component b) is from 0.1 to 10 ppm.

27. The process according to claim 15, wherein the ratio of the glucamide component a) to the sulfur synergist b) is from 100:1 to 1:30 preferably from 30:1 to 1:1 by weight.

28. The process according to claim 15, wherein the concentration of the composition according to claims 1 to 13 is from 0.2 to 40 wt.-ppm.

Description

EXAMPLES

[0078] If not stated otherwise, references to % or ppm mean weight-% or weight-ppm throughout this specification.

[0079] The following abbreviations to substances have been used in this section:

[0080] The samples and the results are summarized below:

##STR00004##

Abbreviations

[0081] ATG: Ammonium Thioglycolate (thiol)/b1
TG-TEA: Thioglycolate salt with triethanolamine (thiol)/b1
MET: Mercaptoethanol (thiol)/b1

ATS: Ammoniumthiosulfate (Thiosulfate)/b2

[0082] OMet: N-Oleyl-Methionine (thioether)/b1
OMet-TEA: N-Oleyl Methionine salt with triethanolamine (thioether)/b1

TU: Thiourea/b3

[0083] AS: Ammonium sulfate
IAA: Isoascorbic acid
TM: Test material/glucamide
Ref: Reference (sodium benzoate) in OECD 306 test
mpy: mill-inch per year

[0084] Firstly the environmental data were determined according to OECD 306 biodegradability and aquatic toxicity testing on the glucamides and the result is outlined in Tables 1 and 2.

TABLE-US-00001 TABLE 1 OECD 306 biodegradation of additives and aquatic toxicity testing of Glucamide #1 Day [%] No. 7 14 21 28 1.1 Glucamide #1 15 25 33 31 1.2 MET 5 6 8 17 1.3 ATG 9 20 33 39 1.4 OMet 60 60 60 60 1.5 TU 19 32 20 55 1.6 Reference 78 74 86 68 Range-finding Definitive No. Aquatic Toxicity Test result [mg/l] result [mg/l] 1.7 Glucamide # 1 72 hr 335.40 165.24 Algae EC.sub.50

TABLE-US-00002 TABLE 2 Marine BODIS and aquatic toxicity testing of Glucamide #5 ThOD Addition rate Day [%] No. [mgO.sub.2/mg] [mg/bottle] 7 14 21 28 2.1 Glucamide # 5 2.056 4.864 23 33 37 42 2.2 TM + Ref 45 52 57 64 2.3 Reference 1.60 12.00 66 77 81 83 Range-finding Definitive No. Aquatic Toxicity Test result [mg/l] result [mg/l] 2.4 Glucamide # 5 72 hr 6.199 4.55 Algae EC.sub.50

[0085] The OECD 306 test is disclosed in the April 2005 version of the OECD guideline for testing of chemicals. The results clearly show the positive results for biodegradation and toxicity of the glucamides and the Sulphur synergists described in this application. A test for ATG was not conducted as this is an inorganic salt.

[0086] In order to evaluate the corrosion inhibition efficacy of the formulations, two different test methods were employed: rotating cylinder electrode (RCE) tests and high pressure, high temperature (HPHT) autoclave weight loss tests. For all testing, the following standard brine composition was used (as outlined in table 3):

TABLE-US-00003 TABLE 3 Synthetic brine composition for corrosion testing Ionic Species Ionic Concentration [mg/l] Sodium (Na.sup.+) 914.87 Potassium (K.sup.+) 32.93 Magnesium (Mg.sup.2+) 110.24 Calcium (Ca.sup.2+) 34.68 Strontium (Sr.sup.2+) 1.15 Chloride (Cl.sup.) 1644.95 Bicarbonate (HCO.sub.3.sup.) 12.11 Sulfate (SO.sub.4.sup.2) 229.58

[0087] A gas composition of 100% CO.sub.2 was used throughout testing.

[0088] The metallurgy of the coupons tested was C1018 carbon steel for RCE testing and HPHT autoclave testing. Coupons were polished mechanically using 320 grit silicon-carbide (SiC) paper, 400 grit SiC paper, then 600 grit SIC paper and rinsed with water then acetone prior to testing.

[0089] The rotating cylinder electrode (RCE) tests were conducted in Pyrex glass reaction kettles that were heated to 150 F. The testing solution was comprised of 900 mL of brine. The electrode rotation rate was set at 2000 RPM, which generated a wall shear stress of 7.0 Pa. Linear polarization resistance (LPR) measurements were made with a Gamry electrochemical measurement system. The working electrode was made of a 1018 carbon steel (CS) cylinder with a surface area of 3.16 cm.sup.2. A Hastelloy C276 electrode was used as a pseudo-reference, and a titanium rod was used as the counter electrode. The corrosion inhibitors were added based on the brine volume after the baseline corrosion rate was monitored for approximately 1.5 hours. The baseline corrosion rate corresponds to the blank corrosion value. Upon completion of the tests, the electrodes were cleaned in an inhibited acid bath according to ASTM G1 C.3.5, and weighed to 0.1 mg.

[0090] High pressure, high temperature (HPHT) rotating cage autoclave (RCA) tests were used to simulate more realistic and extreme conditions for the purpose of evaluating system corrosivity as well as inhibitor performance. The test solution consisted of 800 mL of brine. The brine was deoxygenated using 100% carbon dioxide gas before final pressurization into the autoclaves. Three weight loss corrosion coupons fixed on a PEEK (Polyether ether ketone) insulated cage were used in each autoclave. General corrosion rates were calculated by weight loss measurement according to ASTM G170 (and associated standards referenced therein). Test conditions were constant in all examples with a temperature of 66 and 149 C. at a constant pressure of 34.5 bar, the inhibitors were dosed in at a variety of dose rates ranging from 150 to 300 ppm (based on each inhibitor component) and the tests were run for 3 to 6 days.

[0091] The surfaces of the electrodes and coupons were analyzed after each test for pitting potential by using a high powered metallurgical microscope. The reflected light microscope was capable of analyzing samples up to 1,000-times magnification. The microscope was mounted with a camera and included brightfield, darkfleld, and Differential Interface Controls (DIC) modes.

TABLE-US-00004 TABLE 4 Corrosion test (RCE) Sugar Sulfur-based Corrosion Rate [mpy] Protection [%] derivative derivative 2 hr 2 hr after Final 2 hr after Final No. Example kind [ppm] [ppm] baseline Cl dose 3 hr Cl dose 3 hr 4.1 Comparative 1 Glucamide #1 (12) None 158.4 44.2 11.6 72.1 92.7 4.2 Comparative 2 Glucamide #2 (12) None 165.7 34.6 10.2 79.1 93.8 4.3 Comparative 3 Glucamide #3 (12) None 168.2 44.8 10.9 73.4 93.5 4.4 Comparative 4 Glucamide #4 (12) None 173.4 41.6 9.8 76.0 94.3 4.5 Comparative 5 Glucamide #5 (12) None 159.1 38.6 9.6 75.7 94.0 4.6 Comparative 6 Glucamide #6 (12) None 181.7 42.4 10.6 76.7 94.2 4.7 Comparative 7 None ATG (12) 168.6 47.6 14.5 71.8 91.4 4.8 Comparative 8 None MET (12) 178.3 45.6 15.4 74.4 91.4 4.9 Comparative 9 None ATS (12) 158.5 38.7 13.9 75.6 91.2 4.10 Comparative 10 None OMet (12) 176.9 39.6 12.9 77.6 92.7 4.11 Comparative 11 None TU (12) 158.1 38.5 10.9 75.6 93.1 4.12 Comparative 12 Imidazoline acetate - None 172.6 72.3 21.6 58.1 87.5 12 ppm Commercial Product A 4.13 Inventive 1 Glucamide #1 (10) ATG (2) 168.2 32.6 5.4 80.6 96.2 4.14 Inventive 2 Glucamide #1 (11) ATG (1) 176.8 30.9 5.5 82.5 96.9 4.15 Inventive 3 Glucamide #1 (10) MET (2) 182.6 36.6 4.3 80.0 97.6 4.16 Inventive 4 Glucamide #1 (10) ATS (2) 156.9 28.6 3.4 81.8 97.8 4.17 Comparative 13 IAA (10) ATS (2) 176.1 60.9 17.6 65.4 90.0 4.18 Comparative 14 Glucamide #1 (10) AS (2) 165.9 50.6 15.9 69.5 90.4 4.19 Inventive 5 Glucamide #1 (10) OMET (2) 184.3 38.1 5.7 79.3 96.9 4.20 Inventive 6 Glucamide #1 (10) OMET (1), ATG (1) 176.5 32.6 4.8 81.5 97.3 4.21 Inventive 7 Glucamide #1 (10) TG-TEA (2) 156.8 30.0 3.2 80.9 98.0 4.22 Inventive 8 Glucamide #1 (10) OMet-TEA (2) 166.7 29.1 4.0 82.5 97.6 4.23 Inventive 9 Glucamide #1 (10) TU (2) 178.7 29.3 5.0 83.6 97.2

[0092] The HPHT RCA results are displayed in Table 5 in which a comparison is made for the following conditions:

[0093] 1. 66 C., 34.5 bar, 700 rpm, 3 days

[0094] 2. 149 C., 27.6 bar, 700 rpm, 5 days

TABLE-US-00005 TABLE 5 HPHT RCA testing results at 66 C. and 149 C. Average Average Corrosion Rate Corrosion Rate Glucamide Sulphur synergist [mpy] [mpy] No. Product (amount in ppm) (amount in ppm) At 66 C. At 149 C. 5.1 Blank 321.37 434.85 5.2 Comparative 1 Glucamide #1 (150) None 6.25 41.90 5.3 Comparative 2 Glucamide #2 (150) None 4.23 35.66 5.4 Comparative 3 Glucamide #3 (150) None 4.81 36.10 5.5 Comparative 4 Glucamide #4 (150) None 3.62 29.73 5.6 Comparative 5 Glucamide #5 (150) None 3.87 32.76 5.7 Comparative 6 Glucamide #6 (150) None 3.92 35.79 5.8 Comparative 7 None ATG (150) 6.32 40.61 5.9 Comparative 8 None MET (150) 5.21 38.12 5.10 Comparative 9 None ATS (150) 4.89 34.87 5.11 Comparative 10 None OMet (150) 7.89 44.45 5.12 Comparative 11 None TU (150) 6.02 42.09 5.13 Comparative 12 Imidazoline acetate - None 11.24 76.20 150 ppm Commercial Product A 5.14 Inventive 1 Glucamide #1 (75) ATG (75) 2.74 20.8 5.15 Inventive 2 Glucamide #1 (120) ATG (30) 1.89 21.7 5.16 Inventive 3 Glucamide #1 (75) MET (75) 2.24 22.8 5.17 Inventive 4 Glucamide #1 (75) ATS (75) 2.65 24.1 5.18 Comparative 13 IAA (75) ATS (75) 7.53 46.3 5.19 Comparative 14 Glucamide #1 (75) AS (75) 6.79 45.2 5.20 Inventive 5 Glucamide #1 (75) OMET (75) 2.55 22.9 5.21 Inventive 6 Glucamide #1 (100) OMET (20), ATG (30) 2.31 25.0 5.22 Inventive 7 Glucamide #1 (75) TG-TEA 75) 2.03 26.6 5.23 Inventive 8 Glucamide #1 (75) OMet-TEA (75) 2.11 23.6 5.24 Inventive 9 Glucamide #1 (75) TU (75) 2.41 21.9

[0095] Comparative examples 1 to 6 show the results of the various glucamides 1 to 6, which already show encouraging results as described in DE-102014003367. Comparative examples 7 to 11 show the results for the Sulphur based materials only. As a comparison to the glucamides only, comparative example 12 shows the results obtained when using imidazole acetate as a reference sample, which shows much worse results. Inventive examples 1-9 describe the use of a thiol, thio ether, thioacetic acid (as inorganic or organic salt), N-Oleyl-methionine (free acid or organic salt), thiourea or thiosulfate, which show a dramatic increase in performance over the glucamides or Sulphur-based materials only and a synergistic effect when using these sulfur-based derivatives, or combinations thereof. Comparative example 13, shows the effect of replacement of the glucamide by Isoascorbic acid analogous as described in U.S. Pat. Nos. 4,784,778 and 4,784,779 and shows the beneficial effect of the glucamide. The use of a sulfate as described in comparative example 14 (to DE-102014003367) shows that a normal sulfate does not help in corrosion inhibition.

[0096] Surprisingly, it was found that the use of the combination of a glucamide and at least one sulfur-based synergist showed the best effects in corrosion inhibition.