Methods and compositions for clarifying produced waters for boiler feed waters

Patent metadata

Field	Value
Publication number	US-10934189-B2
Application number	US-201715785947-A
Country	US
Kind code	B2
Filing date	Oct 17, 2017
Priority date	Oct 17, 2016
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

Disclosed are methods and compositions for coagulating and clarifying produced waters for use as boiler feed waters, for example for the generation of steam. The methods and compositions are especially useful for treatment of produced waters from steam-injection methods of tertiary oil recovery such as steam-assisted gravitational drainage. Disclosed are compositions comprising a first copolymer having a high molecular weight and bearing a low molar cationic charge and a second copolymer having a lower molecular weight and bearing a high molar cationic charge. The compositions are suitable for addition as coagulants to produced waters that have been treated by warm lime softening. Also disclosed are methods of treating produced waters from steam-injection oil recovery for use as boiler feed waters to generate steam in such steam injection methods.

First claim

What is claimed is:

1. A method of treating a water source, the method comprising:
(i) combining a water source and a softening agent to make a softened water having a temperature of from about 45° C. to about 80° C. and a pH of about 9.5 to about 11, the softening agent selected from calcium hydroxide, calcium oxide, sodium carbonate, potassium carbonate, or any combination thereof, wherein the softened water comprises a colloidal calcium carbonate, a colloidal magnesium hydroxide, or a combination thereof;
(ii) coagulating the colloidal calcium carbonate, the colloidal magnesium hydroxide, or the combination thereof, wherein the coagulating consists of combining the softened water with
(a) a DADMAC/acrylamide copolymer having a number average molecular weight from about 1,000,000 daltons to about 10,000,000 daltons and a cationic mole charge of about 10% to about 30%,
(b) an epichlorohydrin/dimethylamine copolymer having a number average molecular weight of about 10,000 daltons to about 25,000 daltons, wherein the weight ratio of the DADMAC/acrylamide copolymer to the epichlorohydrin/dimethylamine copolymer is about 1:1.4,
(c) optionally water, and
(d) optionally ammonium sulfate

to make a coagulated water; and
(iii) flocculating the coagulated water, wherein the flocculating consists of combining a one or more flocculating agents and optionally water with the coagulated water to form a flocculated water comprising a floc, wherein the one or more flocculating agents is selected from the group consisting of homopolymers and copolymers comprising the residues of monomers selected from N-vinyl pyrrolidone, N-vinyl formamide, N,N dimethylacrylamide, N-vinyl acetamide, N-vinylpyridine, N-vinylimidazole, isopropyl acrylamide, acrylic acid, a salt of acrylic acid, methacrylic acid, a salt of methacrylic acid, ethylene glycol methacrylate, 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethydiallylammonium chloride, acrylamido propyltrimethyl ammonium chloride, methacrylamido propyltrimethyl ammonium chloride, and any combination of the residues, oxyalkylated alcohols, polyacrylamide, acrylamide copolymers bearing a negative molecular charge, polysaccharides, poly(methacrylamide), anionic polymers, and any combination thereof,
wherein the water source comprises calcium ions, magnesium ions, bicarbonate ions, or any combination thereof.

2. The method of claim 1 , wherein the water source comprises a produced water from a steam-assisted gravity drainage process.

3. The method of claim 1 , wherein the one or more flocculating agents is selected from the group consisting of oxyalkylated alcohols, and homopolymers and copolymers comprising the residues of monomers selected from the group consisting of N-vinyl pyrrolidone, N-vinyl formamide, N-vinyl acetamide, acrylic acid, a salt of acrylic acid, methacrylic acid, a salt of methacrylic acid, ethylene glycol methacrylate, 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, and any combination of the residues.

4. The method of claim 3 , wherein the one or more flocculating agents consists of polyacrylic acid and/or a salt thereof.

5. The method of claim 1 , the method further comprises removing at least a portion of the floc from the flocculated water to provide a clarified water.

6. The method of claim 5 , further comprising purifying the clarified water in a further purification step selected from ion exchange, filtration, evaporator crystallizer treatment, electrodialysis, dissolved gas flotation, plate coalescence, or any combination thereof.

7. The method of claim 5 , further comprising heating the clarified water in a boiler to produce steam.

8. The method of claim 7 , further comprising applying the steam to a steam-assisted gravity drainage process to recover heavy crude oil from oil sands.

9. The method of claim 1 , wherein the softening agent further comprises sodium aluminate.

10. The method of claim 1 , wherein the colloidal calcium carbonate, the colloidal magnesium hydroxide, or the combination thereof has an average particle size as measured by dynamic light scattering of about 1 nm to about 500 nm.

11. The method of claim 10 , wherein the coagulate has an average particle size as measured by dynamic light scattering and/or laser diffraction is from 100 times to 1,000 times the average particle size of the colloidal precipitate.

12. A composition consisting of:
(a) a DADMAC/acrylamide copolymer having a number average molecular weight from about 1,000,000 daltons to about 10,000,000 daltons and a cationic charge of about 30 mole percent to about 10 mole percent;
(b) an epichlorohydrin/dimethylamine copolymer having a number average molecular weight from about 10,000 daltons to about 25,000 daltons, wherein the weight ratio of the DADMAC/acrylamide copolymer to the epichlorohydrin/dimethylamine copolymer is about 1:1.4;
(c) water;
(d) optionally ammonium sulfate; and
(e) a flocculating agent selected from oxyalkylated alcohols, and homopolymers and copolymers comprising the residues of monomers selected from N-vinyl pyrrolidone, N-vinyl formamide, N-vinyl acetamide, acrylic acid, a salt of acrylic acid, methacrylic acid, a salt of methacrylic acid, ethylene glycol methacrylate, 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, and any combination of the residues.

13. The composition of claim 12 , wherein the flocculating agent consists of polyacrylic acid and/or a salt thereof.

Assignees

• Ecolab Usa Inc

Inventors

• Burney Jason R
• Murcia Michael J

Classifications

• C02F5/02

  Softening water by precipitation of the hardness · CPC title

• C08G73/0226

  Quaternisation of polyalkylene(poly)amines · CPC title

• C08L39/04

  Homopolymers or copolymers of monomers containing heterocyclic rings having nitrogen as ring member · CPC title

• C08G73/0213

  Preparatory process · CPC title

• C08L33/26

  Homopolymers or copolymers of acrylamide or methacrylamide · CPC title