# US 11,078,404 B2 · Methods and materials for controlled release of materials in a subterranean reservoir

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- Number: US 11,078,404 B2
- Document ID: US11078404B2
- Status: Granted
- Kind: B2
- Application number: 16/547,201
- Filed: 2019-08-21
- Published: 2019-12-12
- Granted: 2021-08-03
- Earliest claimed: 2016-06-27
- Assignees: Research Triangle Institute
- Applicants: Research Triangle Institute
- Inventors: Leah Marie Johnson; Ginger Denison Rothrock; Chasity Antoninette Norton; Nicolas Daniel Huffman; Jeffrey Brent Mecham
- Web page: https://patentgrep.com/patent/US11078404B2

## CPC

- C09K 8/588: characterised by the use of specific polymers {(polymeric surfactants C09K8/584)}
- C09K 8/508: macromolecular compounds {(C09K8/512 takes precedence)}
- C09K 8/512: containing cross-linking agents
- C09K 8/516: characterised by their form or by the form of their components, e.g. encapsulated material
- E21B 33/138: Plastering the borehole wall; Injecting into the formation
- E21B 43/20: Displacing by water
- C09K 2208/10: Nanoparticle-containing well treatment fluids
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

The present disclosure relates to delivery and release systems, such as core-shell particles. An exemplary composition according to the disclosure can include a degradable polymeric shell surrounding a core that includes a crosslinker, which can encompass a metal, such as chromium. The core-shell particles can be provided with a gel-forming polymer, such as a polyacrylamide, into a subterranean reservoir having conditions such that the shell of the core-shell polymer degrades, and the so-released metal is effective to at least partially crosslink the gel-forming polymer to form a gel. The so-formed gel can be effective to control water flow through the subterranean reservoir, such as in relation to a waterflood of the reservoir.

## Claims

### Claim 1

A method for controlling water flow through a subterranean reservoir, the method comprising;
delivering to a portion of the subterranean reservoir a gelation system comprising: a gel-forming polymer configured for crosslinking with a crosslinker; and a controlled-release delivery particle comprising a degradable polymeric shell surrounding a core comprising the crosslinker;
wherein the subterranean reservoir exhibits conditions such that the crosslinker is released from the core of the controlled-release delivery particle via degradation of the polymeric shell, and the released crosslinker crosslinks the gel-forming polymer to form a gel that at least partially prevents flow of the water through the portion of the subterranean reservoir where the so-formed gel is located; and
wherein the degradable polymeric shell comprises a polymer selected from the group consisting of polyureas, polyurethanes, and combinations thereof.

### Claim 2 (depends on 1)

The method of claim 1, wherein the gel-forming polymer is selected from the group consisting of polyacrylamides, partially hydrolyzed polyacrylamides, polyvinyl alcohols, biopolymers, and combinations thereof.

### Claim 3 (depends on 2)

The method of claim 2, wherein the gel-forming polymer comprises a polyacrylamide-co-acrylic acid.

### Claim 4 (depends on 1)

The method of claim 1, wherein the gel-forming polymer during the delivering of the gelation system to a portion of the subterranean reservoir is in the form of a hydrated solution.

### Claim 5 (depends on 4)

The method of claim 4, wherein the hydrated solution, in a non-crosslinked form, has a viscosity that is greater than the viscosity of water but is less than 50 cP at a temperature of about 25° C.

### Claim 6 (depends on 1)

The method of claim 1, wherein the gel-forming polymer has a weight average molecular weight of about 50,000 Da to about 2,000,000 Da.

### Claim 7 (depends on 1)

The method of claim 1, wherein the crosslinker is source of a metal ion.

### Claim 8 (depends on 7)

The method of claim 7, wherein the metal ion is selected from the group consisting of Cr(III), Cr(IV), Ti(IV), Al(III), Zr(IV), and combinations thereof.

### Claim 9 (depends on 7)

The method of claim 7, wherein the crosslinker is selected from the group consisting of chromium propionate, chromium acetate, chromium chloride, and combinations thereof.

### Claim 10 (depends on 1)

The method of claim 1, wherein the degradable polymeric shell is configured for one or more of thermal degradation, oxidative degradation, and chemical degradation for release of the crosslinker from the core.

### Claim 11 (depends on 1)

The method of claim 1, wherein the degradable polymeric shell comprises one or more of polymers with hydrolytically cleavable groups that degrade with time, polymers with hydrolytically degradable groups that degrade in aqueous media, polymers with azo cleavable groups, and polymers with thermally degradable azo groups.

### Claim 12 (depends on 1)

The method of claim 1, wherein the degradable polymeric shell is configured to release the crosslinker from the core in response to a change in one or more of pH, temperature, pressure, salinity, shear, water content, and oil content.

### Claim 13 (depends on 1)

The method of claim 1, wherein the controlled release delivery particle has an average size of about 50 nm to about 900 nm.

### Claim 14 (depends on 1)

The method of claim 1, wherein the core further comprises one or more additional agents selected from the group consisting of wettability modifiers, anti-scale agents, surfactants, catalysts, blocking agents, sensors, and combinations thereof.

### Claim 15 (depends on 1)

The method of claim 1, further comprising a different controlled-release delivery particle comprising a degradable polymeric shell surrounding a core comprising one or more agents selected from the group consisting of wettability modifiers, anti-scale agents, surfactants, catalysts, blocking agents, sensors, and combinations thereof.