Composition and method for scavenging sulfides and mercaptans

Abstract

This invention relates to a composition comprising 1.) a metal carboxylate, wherein the metal M is selected from the group consisting of Ag, Cn, Hg, Pb, Sn, Ni, Co, Ca, Fe, Zn and Mn, those metals being present as ions in a +2 or +3 charge state, and wherein the carboxylate anion is derived from a hydrocarbyl monocarboxylic acid having 5 to 20 carbon atoms, or a mixture of such acids, 2.) a solvent selected from the group consisting of water, glycol ethers having from 4 to 15 carbon atoms, alkyl alcohols having from 1 to 10 carbons, and aromatic hydrocarbon solvents having from 6 to 30 carbons, and 3.) an emulsion breaker which is a polymeric nonionic surfactant.

Claims

1. A composition comprising a metal carboxylate, wherein the metal M is selected from the group consisting of Fe and Zn, those metals being present as ions in a +2 or +3 charge state, and wherein the carboxylate anion is derived from a hydrocarbyl monocarboxylic acid having 5 to 20 carbon atoms, or a mixture of such acids, a solvent selected from the group consisting of water, glycol ethers having from 4 to 15 carbon atoms, alkyl alcohols having from 1 to 10 carbons, and aromatic hydrocarbon solvents having from 6 to 30 carbons, and an emulsion breaker which is selected from the group consisting of a polymeric nonionic surfactant and dodecylbenzene sulfonic acid.

2. The composition according to claim 1, wherein the metal carboxylate corresponds to formula (1)
M.sup.a+(R—CO.sub.2).sub.b(OH).sub.c-b   (1) wherein M is zinc, a is 2 or 3, b is 1, 2 or 3, c is (a-b), and R is a hydrocarbyl radical containing from 4 to 19 carbon atoms, or mixtures of such carboxylates.

3. The composition according to claim 1, wherein the metal carboxylate is zinc carboxylate.

4. The composition according to claim 3, wherein the zinc carboxylate corresponds to formula Zn.sub.4(O.sub.2CR).sub.6O, wherein R is a hydrocarbyl radical containing from 4 to 19 carbon atoms, or mixtures of such carboxylates.

5. The composition according to claim 1, wherein the metal carboxylate is oil-soluble.

6. The composition according to claim 1, wherein the acids R—COOH, from which the metal carboxylate is derived, are liquid below 100° C.

7. The composition according to claim 1, wherein M is Fe.

8. The composition according to claim 1, wherein the metal carboxylate of formula (1) is the salt of a neoacid of the formula (2) ##STR00018## wherein R.sup.1, R.sup.2, and R.sup.3 are each independently alkyl groups containing 1 to 16 carbon atoms, with the total number of carbon atoms contained in R.sup.1, R.sup.2, and R.sup.3 being from 3 to 18.

9. The composition according to claim 1, wherein the metal carboxylate of formula (1) is a salt of an isoacid of formula (3)
R.sup.4—CH.sub.2—COOH   (3) wherein R.sup.4 is an aliphatic, branched hydrocarbyl group containing from 2 to 20 carbon atoms.

10. The composition according to claim 1, wherein the metal carboxylate of formula (1) is a salt of a guerbet acid of formula (4) ##STR00019## wherein R.sup.5 is a hydrocarbyl group containing from 2 to 8 carbon atoms, and R.sup.6 is a hydrocarbyl group containing from 4 to 10 carbon atoms.

11. The composition according to claim 1, wherein the solvent is selected from the group consisting of isopropyl alcohol, methanol, ethanol, propanol, butanol. ethylene glycol, propylene glycol, butylene glycol, oligoethylene glycols, oligopropylene glycols, isopropyl alcohol, toluene, xylene, naphthalene, ethylbenzene, trimethylbenzene, and aromatic naphtha (AN).

12. The composition according to claim 1, wherein the emulsion breaker is a compound of formula (5) ##STR00020## wherein R.sup.7 is C.sub.2 to C.sub.4 alkylene R.sup.8 is C.sub.1 to C.sub.18 alkyl k is a number from 1 to 200 and m is a number from 1 to 100.

13. The composition according to claim 1, wherein the emulsion breaker is dodecylbenzene sulfonic acid.

14. The composition according to claim 1, further comprising a H.sub.2S scavenger, wherein the H.sub.2S scavenger is a compound selected from the group consisting of triazines according to formula (7) ##STR00021## wherein each R.sup.9 is independently selected from the group consisting of C.sub.1 to C.sub.20 straight or branched alkyl groups, or —R.sup.10OH, where R.sup.10 is a C.sub.1 to C.sub.20 straight or branched alkylene group; hemi-acetal compounds of the general formula R.sup.11R.sup.12C(OH)OR.sup.13 wherein R.sup.11, R.sup.12 or R.sup.13 are hydrogen and/or C.sub.1 to C.sub.20 straight or branched alkyl group; hydroxyalkylhydantoins, bis(hydroxyalkyl)hydantoins, and dialkylhydantoins, wherein the alkyl group is a C.sub.1 to C.sub.6 alkyl group; and glyoxal.

15. The composition according to claim 1, further comprising a scale inhibitor selected from the group consisting of 1-hydroxyethane-1,1-diphosphonate, diethylenetriamine penta(methylene phosphonic acid), nitrilo(methylene phosphonic acid), methacrylic diphosphonate homopolymer, polymaleates, polyacrylates, polymethacrylates, polyphosphates, phosphate esters, acrylic acid-allyl ethanolamine diphosphonate copolymer, sodium vinyl sulfonate-acrylic acid-allyl ammonia diphosphonate terpolymer, acrylic acid-maleic acid-diethylene triamine) allyl phosphonate terpolymer and polycarboxylates.

16. The composition according to claim 1, further comprising a scale inhibitor copolymer, wherein the scale inhibitor copolymer comprises a) 0.1 to 10 mol-% of structural units derived from vinylphosphonic acid and/or of a salt thereof, b) 40 to 90 mol-%, of structural units derived from compounds of the formula (12) ##STR00022## and c) 1 to 50 mol-% of structural units derived from compounds of the formula (13) ##STR00023## in which X is OH or NR.sup.14R.sup.15, and R.sup.14 and R.sup.15, independently of one another, are H or C.sub.1-C.sub.4-alkyl.

17. The composition according to claim 1, comprising 0.1 to 80 wt.-% of the metal carboxylate, 1 to 50 wt.-% of the solvent, and 0.1 to 10 wt.-% of at least one emulsion breaker.

18. The composition according to claim 14, comprising the H.sub.2S scavenger in an amount of 1 to 20 wt.-%.

19. The composition according to claim 15, comprising the scale inhibitor in an amount of 0.1 to 5 wt.-%.

20. A process for scavenging sulfhydryl molecules in oilfield operations and process systems, the process comprising adding to a system susceptible to production of sulfhydryl compounds the composition according to claim 1.

Description

EXAMPLES

(1) In the whole specification, all references to percentages are meant to be weight percent relative to the respective whole composition, except if noted otherwise.

Example 1

Scavenger Performance

(2) In order to demonstrate the efficiency of the instant invention in removing sulfhydryl compounds as exhibited by components comprising Group 1, testing was performed focusing on removal of H.sub.2S from an oil/water mixture. All testing was performed at 117° F. (47° C.) by sparging 200 ppm and 1,000 ppm H.sub.2S gas (in a nitrogen matrix) at 0.15 liters per minute through 300 mL of oil (Eagle Ford condensate) and water (in a 50:50 volume ratio of oil to water) while magnetically stirring at 400 rpm. Five different dose rates of the various scavenger chemicals tested were added to the oil/water mixture at 250, 500, 1,000, 2,000 and 4,000 mg/L.

(3) Efficacy was determined as the time required to measure the same concentration of H.sub.2S exiting the test fluid than that entering, i.e. the time required for the scavenger to be 100% spent and loaded with H.sub.2S. The longer the time the more efficient the scavenger. The results have been summarized in Table 1.

(4) TABLE-US-00001 TABLE 1 H.sub.2S scavenger efficiency testing of components that comprise the instant invention and comparative examples from the prior art 200 ppm H.sub.2S (min-sec) 1,000 ppm H.sub.2S (min-sec) 250 500 1000 2000 4000 Example Chemical ppm ppm ppm ppm ppm 1 (C) 1,3,5 1′50″ 3′42″ 11′22″ 2′12″ 5′17″ Hexahydrotriethanol- 1,3,5 Triazine 2 (C) 1,3,5- 1′45″ 3′37″ 11′05″ 2′03″ 5′03″ trimethylhexahydro- 1,3,5-triazine 3 (C) α,α,α-Trimethyl-1,3,5- 1′48″ 3′40″ 11′15″ 2′07″ 5′10″ triazine-1,3,5(2H,4H,6H)- triethanol 4 (C) 1,6-dihydroxy-2,5- 2′15″ 4′58″ 14′24″ 2′44″ 6′31″ dioxahexane 5 (C) 1,3-Dimethylol-5,5- 2′04″ 4′32″ 12′49″ 2′24″ 5′53″ dimethylhydantoin 6 (C) Zinc neodecanoate 3′21″ 8′21″ 25′50″ 3′04″ 7′48″ 7 (C) Zinc 2-ethylhexanoate 3′15″ 8′05″ 24′58″ 2′52″ 7′31″ 8 Instant Invention 3′25″ 8′29″ 26′02″ 3′17″ 7′59″ Formulation

(5) The inventive formulation of example 8 was as follows: 75% zinc-neodecanoate, 24.3% heavy aromatic naphtha, 0.3% of DDBSA (as described in formula (6)), 0.2% Nonyl acid catalyzed resin with up to 5 mol ethylene oxide (EO) per OH group and an approximate molecular weight of 3,500 g/mol as described in formula (5), and 0.2% Group 5 Copolymer (58% AMPS, 38% Acrylic Amide, 2% n-Vinyl Formamide, 2% Vinyl Phosphonic Acid).

(6) It can be seen that all the triazine compounds that comprised comparative examples 1 (C), 2 (C), and 3 (C) performed very similarly. Comparative examples 4 (C) and 5 (C) performed better than the triazine examples but the raw scavengers of this instant invention in examples 6 and 7 outperformed the comparative examples in terms of H.sub.2S loading efficacy.

Example 2

Viscosity Profiles

(7) The purpose of this testing was to determine the effect that Group 2 components had on the viscosity of compositions of the instant invention. Viscosity was measured using a Brookfield viscometer at a constant of 71° F. (22° C.) and ambient pressure. The results have been displayed in Table 2.

(8) TABLE-US-00002 TABLE 2 Viscosity measurements of the instant invention and comparative examples Example Chemistry/Formulation Viscosity (cP) 1 (C) Zinc neodecanoate 9,000 2 (C) Zinc 2-ethylhexanoate 8,500 3 (C) 75% Zinc neodecanoate + 25% MEG 732 4 (C) 75% Zinc 2-ethylhexanoate + 25% MEG 711 5 (C) 75% Zinc neodecanoate + 25% 2-BE 766 6 (C) 75% Zinc 2-ethylhexanoate + 25% 2-BE 728 7 (C) 75% Zinc neodecanoate + 25% HAN 93 8 (C) 75% Zinc 2-ethylhexanoate + 25% HAN 86 9 (C) 75% Zinc neodecanoate + 25% butanol 624 10 (C) 75% Zinc 2-ethylhexanoate + 25% butanol 586 11 (C) 75% Zinc neodecanoate + 25% toluene 137 12 (C) 75% Zinc 2-ethylhexanoate + 25% toluene 124 13 Instant Invention Formulation 139

(9) The inventive formulation of example 13 was 1 as follows: 75% zinc-neodecanoate, 24.3% heavy aromatic naphtha, 0.3% of DDBSA (as described in formula (6)), 0.2% Nonyl acid catalyzed resin with up to 5 mol ethylene oxide (EO) per OH group and an approximate molecular weight of 3,500 g/mol as described in formula (5), and 0.2% Group 5 Copolymer (58% AMPS, 38% Acrylic Amide, 2% n-Vinyl Formamide, 2% Vinyl Phosphonic Acid).

(10) In Table 2 MEG is monoethylene glycol, 2-BE is 2-butoxyethanol, and HAN is heavy aromatic naphtha. It can be seen that viscosity can be dramatically reduced by adding relatively low amounts of solvent compared to the two comparative Group 1 examples. The most effective Group 2 components to add to the Group 1 components for viscosity reduction were heavy aromatic naphtha and/or toluene.

Example 3

Emulsion Testing

(11) It is well known to one skilled in the art that solids in an oil/water mixture can cause significant emulsion stability especially if those solids are liable to oil wet and sit on the oil/water interface. This is the case with zinc sulfide and as this is a reaction product of preferred embodiments of the instant invention, the test work presented here shows how Group 3 emulsion breaker components assist with the resolution of emulsions caused by use of the Group 1 components.

(12) The testing was performed using the standard bottle test, well known to one skilled in the art. This involved taking 100 mL of different ratios of crude oil and synthetic brine in a prescription bottle and agitating them on a mechanical shaker in order to induce emulsions. All tests were performed at a temperature of 140° F. (60° C.) and separation observed for 10 minutes. For tests that contained ZnS, the ZnS was added as a substance in a known concentration. The time taken for emulsion resolution was recorded as water drop rate, crude oil dehydration and interface quality. Water drop rate is the rate at which water volumetrically separates from the crude oil. It is desirable for this to be as quick as possible, achieving a maxima in under 5 minutes is more desirable in oilfield operations. The crude oil dehydration is measured as base sediment and water % (BS&W %) which in this test is the water content that remains in the oil at the end of the test. This gives a secondary indication of performance because while water drop is one desirable feature of a good demulsifier, the remaining water left in the crude oil is ideally <2%, more desirable is <1%. Finally the quality of the interface is important. A clean interface, i.e. a very uniform layer existing between the oil and water, rather than a baggy, or inhomogeneous interface is most desirable. This is because the way oilfield separation process equipment works requires a clean interface to be most efficient. These tests were performed using comparative components and preferred embodiments of the instant invention to show how inclusion of Group 3 components significantly enhanced the resolution of emulsions and that examples from the known art cause substantial challenges with respect to emulsion formation. The results have been summarized in Tables 3 and 4 which show formulations and performance data respectively.

(13) TABLE-US-00003 TABLE 3 Formulations tested for emulsion resolution Example Formulation 1 (C) Zinc-neodecanoate 2 (C) 75% zinc-neodecanoate, 25% HAN 3 75% zinc-neodecanoate, 24% HAN, 1% DDBSA as described in formula (6) 4 75% zinc-neodecanoate, 24% HAN, 1% Nonyl acid catalyzed resin with up to 5 mol ethylene oxide (EO) per OH group and an approximate molecular weight of 3,500 g/mol as described in formula (5) 5 75% zinc-neodecanoate, 24% HAN, 0.5% DDBSA as described in formula (6) and 0.5% Nonyl acid catalyzed resin with up to 5 mol ethylene oxide (EO) per OH group and an approximate molecular weight of 3,500 g/mol as described in formula (5)

(14) TABLE-US-00004 TABLE 4 Emulsion resolution testing of the instant invention and comparative examples Ex. ZnS (from Oil content Water Drop (mL) BS&W Interface Table 3) (vol.-%).sup.1 (wt.-%) 1 min 2 min 3 min 4 min 5 min 10 min (%) Quality 1 (C) 50 0 35 41 48 50 50 50 3.2 Good, sharp 50 0.5 21 24 27 31 33 41 6.3 Poor, baggy 70 0 12 18 26 30 30 30 2.8 Good, sharp 70 0.5 6 8 10 13 14 19 5.9 Poor, baggy 2 (C) 50 0 37 42 50 50 50 50 2.9 Good, sharp 50 0.5 22 23 29 34 36 44 6.1 Poor, baggy 70 0 14 19 28 30 30 30 2.4 Good, sharp 70 0.5 7 8 12 14 16 21 5.7 Poor, baggy 3 50 0 43 48 50 50 50 50 1.4 Good, sharp 50 0.5 34 38 42 44 47 50 2.3 Good, sharp 70 0 22 29 30 30 30 30 0.9 Good, sharp 70 0.5 16 21 27 29 30 30 1.9 Good, sharp 4 50 0 42 47 49 50 50 50 1.6 Good, sharp 50 0.5 32 36 40 43 46 50 2.7 Good, sharp 70 0 21 28 30 30 30 30 1.0 Good, sharp 70 0.5 14 20 26 28 30 30 2.1 Good, sharp 5 50 0 48 50 50 50 50 50 0.3 Good, sharp 50 0.5 46 49 50 50 50 50 0.3 Good, sharp 70 0 27 29 30 30 30 30 0.1 Good, sharp 70 0.5 24 28 30 30 30 30 0.2 Good, sharp .sup.1The remainder of the 100% is brine

(15) It can be seen that the presence of ZnS in the oil/water mixtures causes separation issues via emulsion formation. The presence of small concentrations of emulsion breaker bases helps to resolve these emulsions, in Example 5 which is a preferred embodiment of the instant invention, a formulated emulsion breaker package was used to show how complete emulsion resolution can be obtained that could be used as a field solution in order to resolve the challenges caused by the prior art examples.

Example 4

Breakdown Product Inhibition

(16) A further preferred embodiment of the instant invention is to inhibit the formation of undesirable solids. An example is the inhibition of ZnS solids caused by the reaction of preferred embodiments from Group 1 with H.sub.2S. Preferred embodiments from Group 5 were included with a preferred embodiment formulation comprising components from Group 1, 2 and 3 and tested for inhibition of undesirable solid formation.

(17) The various formulations were tested at various concentrations in a 50:50 oil/water mixture (as described in Example 1). At the end of the test the total fluids were filtered through a 0.45 pm filter and the solids captured weighted and characterized. A high amount of solids measured indicated poor inhibition of ZnS, and the composition confirmed using x-ray diffraction. The results of this testing has been summarized in Table 5 and 6 which show the formulations tested and performance of these formulations respectively.

(18) TABLE-US-00005 TABLE 5 Formulations tested for ZnS solids deposition potential Example Formulation 1 (C) Zinc-neodecanoate 2 (C) 75% zinc-neodecanoate, 25% HAN 3 75% zinc-neodecanoate, 24% HAN, 1% DDBSA as described in formula (6) 4 75% zinc-neodecanoate, 24% HAN, 1% Nonyl acid catalyzed resin with up to 5 mol ethylene oxide (EO) per OH group as described in formula (5) 5 75% zinc-neodecanoate, 24% HAN, 0.5% DDBSA as described in formula (6) and 0.5% Nonyl acid catalyzed resin with up to 5 mol ethylene oxide (EO) per OH group and an approximate molecular weight of 3,500 g/mol as described in formula (5) 6 75% zinc-neodecanoate, 24.3% heavy aromatic naphtha, 0.3% of DDBSA (as described in formula (6)), 0.2% Nonyl acid catalyzed resin with up to 5 mol ethylene oxide (EO) per OH group and an approximate molecular weight of 3,500 g/mol as described in formula (5), and 0.2% Group 5 Copolymer (58% AMPS, 38% Acrylic Amide, 2% n-Vinyl Formamide, 2% Vinyl Phosphonic Acid).

(19) TABLE-US-00006 TABLE 6 Results of ZnS solids deposition control Example (from Table 5 Formulation Mass of Composition of Inorganic table 5) Concentration (ppm) Solids (g) Component of Solids 1 (C) 1,000 0.0171 Zinc sulfide 5,000 0.0867 Zinc sulfide 10,000 0.1682 Zinc sulfide 2 (C) 1,000 0.0160 Zinc sulfide 5,000 0.0649 Zinc sulfide 10,000 0.1269 Zinc sulfide 3 1,000 0.0127 Zinc sulfide 5,000 0.0627 Zinc sulfide 10,000 0.1247 Zinc sulfide 4 1,000 0.0149 Zinc sulfide 5,000 0.0635 Zinc sulfide 10,000 0.1245 Zinc sulfide 5 1,000 0.0148 Zinc sulfide 5,000 0.0630 Zinc sulfide 10,000 0.1252 Zinc sulfide 6 1,000 0.0027 Zinc sulfide 5,000 0.0131 Zinc sulfide 10,000 0.03468 Zinc sulfide

(20) It can be seen that the amount of zinc sulfide byproduct formed upon sparging through excess H.sub.2S in the comparative examples is significant when compared to the inventive example number 6 which shows clear dispersion of ZnS solids.