# US 9,518,208 B2 · Gelling agent for water shut-off in oil and gas wells

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- Number: US 9,518,208 B2
- Document ID: US9518208B2
- Status: Granted
- Kind: B2
- Application number: 14/658,536
- Filed: 2015-03-16
- Published: 2016-03-10
- Granted: 2016-12-13
- Earliest claimed: 2014-09-10
- Applicants: Kuwait Institute for Scientific Research
- Inventors: Shawqui M. Lahalih
- Web page: https://patentgrep.com/patent/US9518208B2

## CPC

- C09K 8/42: Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells (compositions for plastering C09K8/50)
- C09K 8/5083: {obtained by reactions only involving carbon-to-carbon unsaturated bonds}
- C09K 8/512: containing cross-linking agents
- C09K 8/882: {obtained by reactions only involving carbon-to-carbon unsaturated bonds}
- C09K 8/885: {obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds}
- C09K 8/887: {containing cross-linking agents}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

The gelling agent for water shut-off in oil and gas wells is a composition that forms a gel to reduce or eliminate the flow of water in a gas or oil well. The composition is formed by mixing polyvinyl alcohol, a polyvinyl alcohol copolymer, or mixtures thereof with an amino-aldehyde oligomer, such as urea formaldehyde or melamine formaldehyde, with or without a cross-linker. The polymer composition can be used to minimize or completely shut off excess water production with insignificant reduction in hydrocarbon productivity.

## Claims

### Claim 1

A gelling agent for water shut-off in oil and gas wells, comprising:
a water soluble polymer selected from the group consisting of polyvinyl alcohol, a polyvinyl alcohol copolymer and mixtures thereof;
an amino aldehyde oligomer selected from the group consisting of urea formaldehyde and melamine formaldehyde;
at least one gelation retarder selected from the group consisting of lignosulfonates and ethyl acetate;
a cross-linking agent selected from the group consisting of boric acid, acetic acid, borax, ammonium chloride, ammonium sulfate, glyoxal, and glutardialdehyde;
and an aqueous solvent, the water soluble polymer and the amino aldehyde oligomer being mixed in the aqueous solvent to form a polymer solution, the water soluble polymer being between 10% and 50% by weight of the polymer solution, and the amino aldehyde oligomer being between 50% and 90% by weight of the polymer solution.

### Claim 2 (depends on 1)

The gelling agent according to claim 1, wherein the aqueous solvent is selected from the group consisting of deionized water, brine, sea water, and tap water.

### Claim 3 (depends on 1)

The gelling agent according to claim 1, further comprising at least one gelation accelerator selected from the group consisting of sulfonated melamine formaldehyde and sulfonated naphthalene formaldehyde.

### Claim 4

A gelling agent for water shut-off in oil and gas wells, comprising:
a water soluble polymer selected from the group consisting of polyvinyl alcohol, a polyvinyl alcohol copolymer and mixtures thereof;
an amino aldehyde oligomer selected from the group consisting of urea formaldehyde and melamine formaldehyde;
at least one gelation accelerator selected from the group consisting of sulfonated melamine formaldehyde and sulfonated naphthalene formaldehyde;
a cross-linking agent selected from the group consisting of boric acid, acetic acid, borax, ammonium chloride, ammonium sulfate, glyoxal, and glutardialdehyde; and
an aqueous solvent, the water soluble polymer and the amino aldehyde oligomer being mixed in the aqueous solvent to form a polymer solution, the water soluble polymer being between 10% and 50% by weight of the polymer solution, and the amino aldehyde oligomer being between 50% and 90% by weight of the polymer solution.

### Claim 5 (depends on 4)

The gelling agent according to claim 4, wherein the aqueous solvent is selected from the group consisting of deionized water, brine, sea water, and tap water.

### Claim 6

A gelling agent for water shut-off in oil and gas wells, comprising:
10% to 50% by weight of polyvinyl alcohol;
50% to 90% by weight of urea formaldehyde;
0.0125% to 0.05% by weight acetic acid; and
an aqueous solvent.

### Claim 7 (depends on 6)

The gelling agent of claim 6, further comprising Ethyl Acetate.

### Claim 8 (depends on 6)

The gelling agent of claim 6, further comprising 5% to 20% by weight of sulfonated melamine formaldehyde.