ZINC-BASED SULFUR COMPOUND SCAVENGER WITH REDUCED SOLIDS DEPOSITION

Abstract

Certain zinc-based scavengers can scavenge sulfur compounds from fluids containing one or more hydrocarbons, water and the sulfur compound, but may leave deposits of insoluble zinc sulfide (ZnS) which can be problematic. When the zinc-based scavengers are used together with at least one zinc sulfide deposition preventer, deposition of zinc sulfide can be reduced or eliminated. The sulfur compound may be hydrogen sulfide (H.sub.2S). Suitable zinc-based sulfur compound scavengers include, but are not necessarily limited to, a zinc carboxylate, a tetramine zinc carbonate, zinc carbonate, zinc ammonium carbonate, zinc chelates, and/or zinc lignosulfonate. Suitable zinc sulfide deposition preventers include, but are not necessarily limited to, sodium salts of a phosphorous-based polymer, polymeric ammonium salts, acrylic sulfonate non-ionic terpolymers, and/or modified acrylic acid polymers.

Claims

1. A method for scavenging a sulfur compound from a fluid comprising a hydrocarbon, water, and the sulfur compound selected from the group consisting of H.sub.2S, sulfide, bisulfide, and combinations thereof, the method comprising: injecting at least one zinc-based sulfur compound scavenger into the fluid in an amount effective to at least partially scavenge the sulfur compound from the fluid; and injecting at least one zinc sulfide deposition preventer into the fluid in an amount effective to at least partially prevent the deposition of zinc sulfide from the fluid; where injecting the at least one zinc-based sulfur compound scavenger and injecting at least one zinc sulfide deposition preventer occurs in any order or simultaneously.

2. The method of claim 1 where the fluid is a mixed production fluid, where the hydrocarbon is crude oil, and where the water is selected from the group consisting of fresh water, brine, and combinations thereof.

3. The method of claim 1 where the at least one zinc-based sulfur compound scavenger is selected from the group consisting of a zinc carboxylate, a tetramine zinc carbonate, a zinc carbonate, a zinc ammonium carbonate, a zinc chelate, a zinc lignosulfonate, and combinations thereof.

4. The method of claim 1 where the at least one zinc sulfide deposition preventer is selected from the group consisting of sodium salts of a phosphorous-based polymer, polymeric ammonium salts, acrylic sulfonate non-ionic terpolymers, modified acrylic acid polymers, and combinations thereof.

5. The method of claim 1 where the effective amount of the at least one zinc-based sulfur compound scavenger ranges from about 0.25 to about 50 parts zinc to 1 part of the total of sulfur compound.

6. The method of claim 5 where the effective amount of the at least one zinc sulfide deposition preventer ranges from about 0.1 to about 50 parts zinc sulfide deposition preventer to parts zinc-based sulfur compound scavenger.

7. The method of claim 1 where the sulfur compound comprises H.sub.2S.

8. A method for scavenging a sulfur compound from a fluid comprising a hydrocarbon, water, and the sulfur compound selected from the group consisting of H.sub.2S, sulfide, bisulfide, and combinations thereof, the method comprising: injecting at least one zinc-based sulfur compound scavenger into the fluid in an amount effective to at least partially scavenge the sulfur compound from the fluid, where the at least one zinc-based sulfur compound scavenger is selected from the group consisting of a zinc carboxylate, a tetramine zinc carbonate, a zinc carbonate, a zinc ammonium carbonate, a zinc chelate, a zinc lignosulfonate, and combinations thereof; and injecting at least one zinc sulfide deposition preventer into the fluid in an amount effective to at least partially prevent the deposition of zinc sulfide from the fluid, where the at least one zinc sulfide deposition preventer is selected from the group consisting of sodium salts of a phosphorous-based polymer, polymeric ammonium salts, acrylic sulfonate non-ionic terpolymers, modified acrylic acid polymers, and combinations thereof; where injecting the at least one zinc-based sulfur compound scavenger and injecting at least one zinc sulfide deposition preventer occurs in any order or simultaneously.

9. The method of claim 8 where the fluid is a mixed production fluid, where the hydrocarbon is crude oil, and where the water is selected from the group consisting of fresh water, brine, and combinations thereof.

10. The method of claim 8 where the effective amount of the at least one zinc-based sulfur compound scavenger ranges from about 0.25 to about 50 parts zinc to 1 part of the total of sulfur compound.

11. The method of claim 10 where the effective amount of the at least one zinc sulfide deposition preventer ranges from about 0.1 to about 50 parts zinc sulfide deposition preventer to parts zinc-based sulfur compound scavenger.

12. The method of claim 8 where the sulfur compound comprises H.sub.2S.

13. A sulfur compound scavenged fluid comprising: a hydrocarbon; water; the sulfur compound selected from the group consisting of H.sub.2S, sulfide, bisulfide, and combinations thereof; at least one zinc-based sulfur compound scavenger in an amount effective to at least partially scavenge the sulfur compound from the fluid; and at least one zinc sulfide deposition preventer into the fluid in an amount effective to at least partially prevent the deposition of zinc sulfide from the fluid.

14. The sulfur compound scavenged fluid of claim 13 where the hydrocarbon is crude oil, and where the water is selected from the group consisting of fresh water, brine, and combinations thereof.

15. The sulfur compound scavenged fluid of claim 13 where the at least one zinc-based sulfur compound scavenger is selected from the group consisting of a zinc carboxylate, a tetramine zinc carbonate, a zinc carbonate, a zinc ammonium carbonate, a zinc chelates, a zinc lignosulfonate, and combinations thereof.

16. The sulfur compound scavenged fluid of claim 13 where the at least one zinc sulfide deposition preventer is selected from the group consisting of sodium salts of a phosphorous-based polymer, polymeric ammonium salts, acrylic sulfonate non-ionic terpolymers, modified acrylic acid polymers, and combinations thereof.

17. The sulfur compound scavenged fluid of claim 13 where the effective amount of the at least one zinc-based sulfur compound scavenger ranges from about 0.25 to about 50 parts zinc to 1 part of the total of sulfur compound.

18. The sulfur compound scavenged fluid of claim 17 where the effective amount of the at least one zinc sulfide deposition preventer ranges from about 0.1 to about 50 parts zinc sulfide deposition preventer to parts zinc-based sulfur compound scavenger.

19. The sulfur compound scavenged fluid of claim 13 where the sulfur compound comprises H.sub.2S.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a photograph of three bottles containing 50 vol % water and 50 vol % oil taken from a well separator and containing 700 ppm of a zinc-based sulfur compound scavenger, where the bottle of Example 11 contained no zinc sulfide deposition preventer, the bottle of Example 12 contained 500 ppm zinc sulfide deposition preventer, and the bottle of Example 13 contained 1000 ppm zinc sulfide deposition preventer.

DETAILED DESCRIPTION

[0011] It has been discovered that zinc sulfide deposition from the use of a zinc-based sulfur compound scavenger, such as to scavenge H.sub.2S from mixed production in one non-limiting embodiment, can be prevented or reduced by co-injection with a zinc sulfide deposition preventer.

[0012] The fluids treated with a zinc-based sulfur compound scavenger include a hydrocarbon, water, and a sulfur compound, which sulfur compound includes, but is not necessarily limited to H.sub.2S, sulfide, and/or bisulfide. It will be understood that the term zinc-based sulfur compound scavenger will be used interchangeably herein with zinc-based H.sub.2S scavenger. While a major concern is the scavenging of H.sub.2S, it will be appreciated that the same compounds can scavenge other sulfur species including, but not limited to, sulfides and bisulfides. Further, mixed production as defined herein is a fluid that contains a hydrocarbon, such as crude oil and/or condensate, and water, such as brine or fresh water, and associated gas, if any.

[0013] The method is not limited to any order of introduction of the zinc-based sulfur compound scavenger or zinc sulfide deposition preventer into the fluid being treated. To be explicit, these components may be introduced as a single formulation, or by co-injection, or the scavenger is introduced first and the preventer second, or the preventer is introduced first and the scavenger second. In some non-limiting embodiments, it may be less advantageous to inject the scavenger first and the preventer second. It may be likely that the preventer would work better if it is added at the same time or before the formation of zinc sulfide due to scavenger addition.

[0014] Suitable zinc-based sulfur compound scavengers include, but are not necessarily limited to, a zinc carboxylate, a tetramine (2+) zinc carbonate, zinc carbonate, a zinc ammonium carbonate, a zinc chelate, and/or a zinc lignosulfonate. Suitable zinc chelates include, but are not necessarily limited to, zinc ethylenediaminetetraacetic acid (EDTA), zinc 2,3-dimercaptopropanesulfonic acid (DMPS), zinc thiamine tetrahydrofurfuryl disulfide (TTFD), zinc TSQ (6-methoxy-8-toluenesulfonamido-quinoline), and combinations of these.

[0015] Suitable zinc sulfide deposition preventers include, but are not necessarily limited to, sodium salts of a phosphorous-based polymer, polymeric ammonium salts, acrylic sulfonate non-ionic terpolymers, and/or modified acrylic acid polymers. The phosphorous-based polymer may include, but is not necessarily limited to, polymers of 2-propenoic acid, polymers with sodium ethenesulfonate, disodium salt-initiated polymers of peroxydisulfuric acid ([(HO)S(O).sub.2].sub.2O.sub.2), and/or polymeric reaction products with tetrasodium ethenylidenebis[phosphonate]. One non-limiting example of a modified acrylic acid polymers is 2-propenoic acid, polymer with sodium phosphinate (1:1).

[0016] The above zinc sulfide deposition preventers are known ZnS dispersants. However, it was discovered that certain ZnS dispersants did not significantly affect the formation of ZnS solids. These include, but are not necessarily limited to, mixtures of a phosphonate salt with a quaternary ammonium compound, as well as the phosphonate salt or the quaternary ammonium compound used separately.

[0017] With respect to the amount of zinc-based sulfur compound scavenger effective to scavenge sulfides from the fluid, the amount ranges from about 0.25 independently to about 50 parts zinc to 1 part of the total of sulfur compound, where it is remembered that the sulfur compound is H.sub.2S/sulfide/bisulfide in the brine and/or hydrocarbon phase, understanding that the about of sulfide will vary and the amount of zinc in the scavenger will also vary. In this context of amounts, zinc refers to the zinc portion of the zinc-based sulfur compound scavenger. In a different non-restrictive version, the effective amount of scavenger may range from about 0.5 parts independently to about 20 parts zinc to parts H.sub.2S/sulfide/bisulfide. As used herein with respect to a range, the term independently means that any threshold may be used together with any other threshold to give a suitable alternative range. In a non-limiting example in this case, a suitable alternative range can be 20 parts to 50 parts zinc to sulfide compound.

[0018] The amount of zinc sulfide deposition preventer effective to prevent or inhibit ZnS solid formation ranges from about 0.1 parts independently to about 50 parts zinc sulfide deposition preventer to parts zinc-based sulfur compound scavenger; alternatively from about 0.25 parts independently to about 10 parts zinc sulfide deposition preventer to zinc-based sulfur compound scavenger.

[0019] The method described herein is expected to be largely unaffected by pressure and temperature. The method is expected to work at potential production temperatures; in one non-limiting embodiment from about 0? ? C. to about 200? C.

[0020] The mechanism by which the zinc sulfide deposition preventer operates to prevent or inhibit ZnS formation and deposition could be either through dispersion, inhibition, and/or dissolution of ZnS; although the method is not limited by any particular mechanism.

[0021] The zinc-based sulfur compound scavengers described herein are very effective and react very quickly. In applications with very short contact times, they are often the only viable option. The methods described herein can alleviate or eliminate a main drawback of using zinc-based sulfur compound scavenger, namely insoluble solids formation. And while the zinc sulfide deposition preventers described herein significantly reduce insoluble ZnS in the aqueous phase, the zinc sulfide deposition preventer does not adversely affect the sulfide scavenging performance of the scavenger.

[0022] The method and compositions described herein will now be discussed with reference to certain specific Examples which are intended to further illustrate, but not necessarily limit the method and the compositions.

Examples 1-10

[0023] Table I presents the performance in a modified ASTM D5705 test at 49? C., with a two-hour test duration in 70 vol % hydrocarbon/30 vol % brine, where the baseline H.sub.2S content was 5000 ppm. The incumbent was a zinc-based sulfur compound scavenger that was approximately 69.6% zinc, 2-ethylhexanoate neodecanoate complexes where the balance was mostly hydrocarbon solvents with approximately 3.2% 2-butoxyethanol. The New zinc-based sulfur compound scavenger is tetramine zinc (2+) carbonate.

TABLE-US-00001 TABLE I H.sub.2S Scavenging Test Results Dosage, % H.sub.2S Ex. Scavenger ppm Scavenging 1 Incumbent 1 [HSO3518] 300 <60 2 Incumbent 1 500 86 3 Incumbent 1 700 100 4 New Scavenger [HSW810] 300 <60 5 New Scavenger 500 90 6 New Scavenger 700 100

[0024] Field testing was performed with bottles containing multiphase samples taken from a well separator. The test bottles contained 50 vol % water and 50 vol % crude oil. After dosing, the bottles were vigorously hand-shaken individually, and then the headspace H.sub.2S was measured immediately thereby providing a very short contact time. After headspace H.sub.2S measurements, samples were again shaken vigorously by hand and observed for emulsion tendencies over time. The scavenging test results indicated that the New scavenger performed as well as or slightly better than Incumbent 1, but the New scavenger was still able to scavenge H.sub.2S more thoroughly in the tested dosage range, as shown in Table II, where the amounts reported in ppm is the amount of H.sub.2S measured in the head space at the given concentration of scavenger.

TABLE-US-00002 TABLE II H.sub.2S Scavenging Field Test Results Ex. 7 8 9 Chemical Blank New Incumbent 1 Concentration scavenger 100 ppm 800 ppm 225 ppm 425 ppm 500 ppm 0 ppm 0 ppm

[0025] The New scavenger did not have the same emulsion tendency as Incumbent 1. The emulsion observed was no worse than the untreated sample. The only issue observed was the formation of reaction products (ZnS) in the water phase, which could present issues depending on where the ZnS deposits.

Examples 10-17

[0026] Two scale inhibitors were evaluated for possible mitigation of ZnS solids: SI 1 and SI 2. Based on expert recommendation from scale inhibition subject matter experts, the minimum dosage for SI 1 was 500 ppm, the minimum dosage for SI 2 was 50 ppm. Performance was measured using a modified ASTM D5705 test at 49? C., two-hour test duration, with a mixture of 70 vol % hydrocarbon/30 vol % brine. It was found that there was no impact of the ZnS deposition preventer on the New scavenger scavenging performance.

TABLE-US-00003 TABLE III Evaluation of ZnS Inhibitor and Dispersant H.sub.2S Dosage H.sub.2S %, % Ex. Scavenger + SI (ppm) ppm Scavenged 10 Untreated 2500 11 New Scvngr. 700 0 100 12 New Scvngr. + SI 1 700 + 500 0 100 13 New Scvngr. + SI 1 700 + 1000 0 100 14 New Scvngr. + SI 2 700 + 100 0 100 15 New Scvngr. + SI 2 700 + 200 0 100 16 New Scvngr. + SI 2 700 + 500 0 100 17 New Scvngr. + SI 2 700 + 1000 0 100

[0027] Zinc sulfide dispersant SI 2 did not have a significant effect on ZnS solids formation in the water phase even at dosages up to 1000 ppm. However, at the higher dose tested, SI 1 appeared to significantly reduce insoluble ZnS in the aqueous phase as shown in FIG. 1, which is a photograph of the three bottles of Example 11 which contained no zinc sulfide deposition preventer, the bottle of Example 12 which contained 500 ppm zinc sulfide deposition preventer, and the bottle of Example 13 which contained 1000 ppm zinc sulfide deposition preventer. All bottles contained 700 ppm of the New scavenger. It may be seen from FIG. 1 that at 1000 pm of SI 1 there are no ZnS deposits.

[0028] In the foregoing specification, the method has been described with reference to specific embodiments thereof and has been shown as effective in providing a method for inhibiting or preventing ZnS deposition when using a zinc-based sulfur compound scavenger.

[0029] It will be evident that various modifications and changes can be made to the methods and compositions described herein without departing from the broader scope of the invention as set forth in the appended claims. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense. For example, specific zinc-based sulfur compound scavengers, zinc sulfide deposition preventers, sulfide compounds, fluids, hydrocarbons, waters, ratios, dosages, orders of addition, proportions, and time periods thereof falling within the claimed parameters, but not specifically identified or tried in a particular method or composition to prevent or inhibit the formation of ZnS, are expected to be within the scope of this application.

[0030] The present application may suitably comprise, consist, or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. For instance, there may be provided a method for scavenging a sulfur compound from a fluid comprising a hydrocarbon, water, and the sulfur compound selected from the group consisting of H.sub.2S, sulfide, bisulfide, and combinations thereof, where the method comprises, consists essentially of, or consists of injecting at least one zinc-based sulfur compound scavenger into the fluid in an amount effective to at least partially scavenge the sulfur compound from the fluid, injecting at least one zinc sulfide deposition preventer into the fluid in an amount effective to at least partially prevent the deposition of zinc sulfide from the fluid, where injecting the at least one zinc-based sulfur compound scavenger and injecting at least one zinc sulfide deposition preventer occurs in any order or simultaneously.

[0031] Further there may be provided a sulfur compound scavenged fluid comprising, consisting essentially of, or consisting of a hydrocarbon; water; the sulfur compound selected from the group consisting of H.sub.2S, sulfide, bisulfide, and combinations thereof; at least one zinc-based sulfur compound scavenger in an amount effective to at least partially scavenge the sulfur compound from the fluid; at least one zinc sulfide deposition preventer into the fluid in an amount effective to at least partially prevent the deposition of zinc sulfide from the fluid.

[0032] As used herein, the terms comprising, including, containing, characterized by, and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method acts, but also include the more restrictive terms consisting of and consisting essentially of and grammatical equivalents thereof. As used herein, the term may with respect to a material, structure, feature, or method act indicates that such is contemplated for use in implementation of an embodiment of the disclosure and such term is used in preference to the more restrictive term is so as to avoid any implication that other, compatible materials, structures, features, and methods usable in combination therewith should or must be, excluded.

[0033] As used herein, the singular forms a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0034] As used herein, the term and/or includes any and all combinations of one or more of the associated listed items.

[0035] As used herein, relational terms, such as first, second, top, bottom, upper, lower, over, under, etc., are used for clarity and convenience in understanding the disclosure and do not connote or depend on any specific preference, orientation, or order, except where the context clearly indicates otherwise.

[0036] As used herein, the term substantially in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0% met, at least 95.0% met, at least 99.0% met, or even at least 99.9% met.

[0037] As used herein, the term about in reference to a given parameter is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the given parameter).