Compositions and methods for removing heavy metals from fluids

Patent metadata

Field	Value
Publication number	US-2017158976-A1
Application number	US-201514961969-A
Country	US
Kind code	A1
Filing date	Dec 8, 2015
Priority date	Dec 8, 2015
Publication date	Jun 8, 2017
Grant date	—

Abstract

A sulfidic complexing agent is disclosed that includes a suspension or a solution formed by a reaction between a water-soluble metal compound and a water-soluble sulfidic compound. The sulfidic complexing agent has a pH of from about 5 to about 11 and a molar ratio of metal to sulfur of from about 0.1 to about 1,000. The sulfidic complexing agent is useful for removing elemental mercury from a hydrocarbon fluid by contacting the hydrocarbon fluid with the sulfidic complexing agent. The molar ratio of sulfur in the sulfidic complexing agent to mercury in the hydrocarbon fluid is from about 50 to about 2,500. Also disclosed is a method for concurrently transporting and removing a trace amount of volatile mercury in a CO 2 -containing natural gas stream extracted from a subterranean formation. The natural gas stream is transported in a pipeline into which the sulfidic complexing agent is injected. Also disclosed is a method for capturing gas phase elemental mercury from a gas stream in the overhead section of a crude oil distillation unit by contacting the gas stream with the sulfidic complexing agent in the overhead section of the distillation unit to form a treated gas stream.

First claim

What is claimed is:

1 . An aqueous metal sulfide colloid complexing agent comprising a suspension or a solution formed by a reaction between a water-soluble metal compound and a water-soluble sulfidic compound;
wherein the water-soluble metal compound comprises a metal selected from the group consisting of Ti, Zr, Hg, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Ga, In, Tl, Sn, Pb, As, Sb, Bi, Se, Te and combinations thereof; wherein the water-soluble sulfidic compound is selected from the group consisting of sodium polysulfide, ammonium polysulfide, calcium polysulfide, sodium hydrosulfide, potassium hydrosulfide, ammonium hydrosulfide, sodium sulfide, potassium sulfide, calcium sulfide, magnesium sulfide, ammonium sulfide, sulfanes, hydrogen sulfide, sodium thiocarbamate, sodium dithiocarbamate, ammonium thiocarbamate and ammonium dithiocarbamate and mixtures thereof; and wherein the aqueous metal sulfide colloid complexing agent has a pH of from about 5 to about 11 and a molar ratio of metal to sulfur of from about 0.1 to about 1,000.

2 . The aqueous metal sulfide colloid complexing agent according to claim 1 wherein the water-soluble metal compound comprises a metal selected from the group consisting of Mo, W, Mn, Fe, Ni, Cu, Se and combinations thereof.

3 . The aqueous metal sulfide colloid complexing agent according to claim 1 wherein the water-soluble metal compound comprises Mo.

4 . The aqueous metal sulfide colloid complexing agent according to claim 1 wherein the metal in the water-soluble metal compound is in the form of an anion.

5 . The aqueous metal sulfide colloid complexing agent according to claim 1 wherein the water-soluble sulfidic compound is selected from the group consisting of sodium hydrosulfide, ammonium hydrosulfide, sodium sulfide, ammonium sulfide, and combinations thereof.

6 . The aqueous metal sulfide colloid complexing agent according to claim 1 wherein the molar ratio of metal to sulfur is from about 0.25 to about 1,000.

7 . The aqueous metal sulfide colloid complexing agent according to claim 1 wherein the molar ratio of metal to sulfur is from about 0.5 to about 10.

8 . The aqueous metal sulfide colloid complexing agent according to claim 1 , further comprising mercury; wherein the molar ratio of sulfur to mercury in the aqueous metal sulfide colloid complexing agent is at least about 1.

9 . The aqueous metal sulfide colloid complexing agent according to claim 8 wherein the molar ratio of sulfur to mercury is from about 2 to about 100,000.

10 . The aqueous metal sulfide colloid complexing agent according to claim 9 wherein the molar ratio of sulfur to mercury is from about 10 to about 25,000.

11 . The aqueous metal sulfide colloid complexing agent according to claim 1 further comprising an additive selected from the group consisting of a demulsifier, an anti-foam material, an oxygen scavenger, a scale inhibitor, a hydrate inhibitor and combinations thereof.

12 . The aqueous metal sulfide colloid complexing agent according to claim 11 wherein the demulsifier is selected from polyamines, polyamidoamines, polyimines, condensates of o-toluidine and formaldehyde, quaternary ammonium compounds, ionic surfactants, polyoxyethylene alkyl phenols, and mixtures thereof.

13 . The aqueous metal sulfide colloid complexing agent according to claim 11 wherein the hydrate inhibitor is a thermal inhibitor in an amount of from about 5 to about 80 vol %.

14 . The aqueous metal sulfide colloid complexing agent according to claim 13 wherein the hydrate inhibitor is a low dose hydrate inhibitor in an amount from about 0.5 to about 5.0 vol %.

15 . The aqueous metal sulfide colloid complexing agent according to claim 1 wherein the pH is from about 6 to about 8.

16 . The aqueous metal sulfide colloid complexing agent according to claim 1 further comprising an acid neutralizer in an amount from about 0.01 to about 10 wt %.

17 . The aqueous metal sulfide colloid complexing agent according to claim 16 wherein the acid neutralizer comprises methyldiethanol amine.

18 . The aqueous metal sulfide colloid complexing agent according to claim 16 , further comprising an acid selected from the group consisting of carbonic, acetic and combinations thereof in an amount from about 10 ppm to about 1 wt %.

19 . A method for removing elemental mercury from a hydrocarbon fluid comprising:
contacting the hydrocarbon fluid with the aqueous metal sulfide colloid complexing agent of claim 1 in an aqueous phase; wherein the molar ratio of sulfur in the aqueous metal sulfide colloid complexing agent to mercury in the hydrocarbon fluid is from about 50 to about 2,500; and wherein at least about 90% of the mercury in the hydrocarbon fluid is removed from the hydrocarbon liquid and into the aqueous phase.

20 . The method of claim 19 wherein the metal in the water-soluble metal compound is in the form of an anion.

21 . The method of claim 19 wherein the contacting is conducted in the overhead of a crude unit.

22 . The method of claim 19 , further comprising removing the elemental mercury from the aqueous phase by a process selected from the group consisting of ion exchange, distillation, precipitation, settling, filtration, centrifugation and combinations thereof.

23 . The method of claim 19 , further comprising removing the elemental mercury from the aqueous phase by ion exchange.

24 . A method for concurrently transporting and removing a trace amount of volatile mercury in a CO 2 -containing natural gas stream extracted from a subterranean formation, comprising:
obtaining a produced fluid containing natural gas and produced water from the subterranean formation and having an initial concentration of volatile mercury; transporting the produced fluid in a pipeline; and injecting a sulfidic complexing agent in an aqueous phase into the pipeline carrying the produced fluid to form a treated produced fluid; wherein volatile mercury in the produced fluid transported in the pipeline reacts with the sulfidic complexing agent to form at least one non-volatile mercury-containing complex; and wherein the treated produced fluid has a final concentration of volatile mercury lower than the initial concentration of volatile mercury.

25 . The method of claim 24 , further comprising:
separating the treated produced fluid to generate a CO 2 -containing natural gas stream having a reduced concentration of volatile mercury, and an aqueous mixture of produced water, non-volatile mercury-containing complex and unreacted sulfidic complexing agent; and separating the unreacted sulfidic complexing agent and the non-volatile mercury-containing complex from the aqueous mixture, by a process selected from the group consisting of ion exchange, distillation, precipitation, settling, filtration, centrifugation and combinations thereof to generate a recovered sulfidic complexing agent with non-volatile mercury complexes, and treated produced water.

26 . The method of claim 25 , further comprising:
using the treated produced water as the aqueous phase in the injecting step of claim 24 .

27 . The method of claim 24 , wherein the pipeline extends from a well head above the subterranean formation to a hydrocarbon production facility.

28 . The method of claim 24 , wherein the pipeline is

Assignees

• Chevron Usa Inc

Inventors

• O'Rear Dennis John
• Thompson Joshua Allen
• Mahieux Cedrick

Classifications

• E21B43/34

  Arrangements for separating materials produced by the well · CPC title

• C10G29/12

  Halides · CPC title

• C10G29/16

  Metal oxides · CPC title

• B01D11/0492

  Applications, solvents used · CPC title

• C10L3/101 Primary

  Removal of contaminants · CPC title