# US 10,870,791 B2 · Compositions and methods for cross-linking hydratable polymers using produced water

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- Number: US 10,870,791 B2
- Document ID: US10870791B2
- Status: Granted
- Kind: B2
- Application number: 16/101,835
- Filed: 2018-08-13
- Published: 2019-04-04
- Granted: 2020-12-22
- Earliest claimed: 2017-08-14
- Assignees: PfP Industries, LLC
- Applicants: PfP INDUSTRIES, LLC
- Inventors: Asoke Deysarkar; Nikhil Patel; Nathalie Rasolomiarantsoa; James Nguyen; Rajendra Ghimire; Michael J. Callanan; Robert McDaniel; Madhukar Chetty
- Web page: https://patentgrep.com/patent/US10870791B2

## CPC

- C09K 8/685: {containing cross-linking agents}
- C09K 8/725: {Compositions containing polymers}
- C09K 8/885: {obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds}
- C09K 8/887: {containing cross-linking agents}
- C09K 8/90: of natural origin, e.g. polysaccharides, cellulose
- E21B 43/26: by forming crevices or fractures
- E21B 43/267: reinforcing fractures by propping
- 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

Fracturing fluid compositions including a base fluid including a high TDS produced and/or flow back water, brackish water, RO reject water, clear brine, and mixtures thereof with or without added fresh water and systems, and methods for making and using same, where the method includes: (a) adding a first buffer to adjust the pH of a base fluid to an acidic pH, (b) adding a hydratable polymer or polymer slurry to the base fluid to form a hydratable polymer fracturing fluid, (c) adding a cross-linking composition to the hydratable polymer fracturing fluid to form a pre-cross-linked fracturing fluid, and (d) if needed, adding a second buffer to the pre-cross-linked fracturing fluid to adjust the pH of the pre-cross-linked fracturing fluid to form a viscosified fracturing fluid having a crosslinked structure.

## Claims

### Claim 1

A fracturing fluid composition comprising:
a base fluid comprising an elevated total dissolved solids (TDS) water selected from the group consisting of produced water, flow back water, brackish water, reverse osmosis (RO) reject water, clear brine, and mixtures and combinations thereof,
a hydratable polymer composition or a hydratable polymer slurry composition, wherein the hydratable polymer composition or hydratable polymer slurry composition includes one or more gel-forming hydratable polymers and one or more synthetic polymers,
a friction reducer composition including hydrolyzed or partially hydrolyzed hydrolyzable polymers and copolymers,
a cross-linking composition in an amount sufficient to crosslink the gel-forming hydratable polymer to form a fracturing fluid having a crosslinked structure, and
a proppant,
wherein the hydratable polymers are present in an amount less than 10 ppt of the fracturing fluid composition,
wherein the crosslinked structure occurs in the last 25% of a residence time of the fracturing fluid composition in a tubular downhole injection mechanism,
wherein the one or more synthetic polymers and the friction reducer composition reduce drag properties of the fracturing fluid composition as the fracturing fluid composition travels down the tubular downhole injection mechanism into a subterranean formation and enters subterranean formation fractures, and
wherein the crosslinked structure in the fracturing fluid composition improves proppant transport properties, reduces a fracturing fluid composition injection rate, and reduces a volume of water required to created a desired fracture geometry and placement of the proppant into the fractures.

### Claim 2 (depends on 1)

The composition of claim 1, further comprising:
a first buffer in an amount sufficient to adjust a pH of the fracturing fluid composition to an acidic pH to improve hydration of the hydratable polymers and to prevent premature crosslinking of the gel-forming hydratable polymers, and
a second buffer in an amount sufficient to adjust the acidic pH to a final pH sufficient to activate the crosslinking composition to form the crosslinked structure, wherein the final pH is at or above 9.

### Claim 3 (depends on 2)

The composition of claim 2, wherein the acidic pH is less than or equal to pH 7.

### Claim 4 (depends on 3)

The composition of claim 3, wherein the crosslinking composition is capable of producing the crosslinked structure at the acidic pH.

### Claim 5 (depends on 1)

The composition of claim 1, further comprising:
a buffer in an amount sufficient to adjust a pH of the fracturing fluid composition to a final pH sufficient to activate the crosslinking composition to form the crosslinked structure,
wherein the final pH is at or above 9.

### Claim 6 (depends on 1)

The composition of claim 1, wherein the base fluid further includes fresh water.

### Claim 7 (depends on 1)

The composition of claim 1, wherein:
the gel-forming hydratable polymers are selected from the group consisting of galactomannan gums, glucomannan gums, guars, derivatized guars, cellulose derivatives, and mixtures or combinations thereof,
the synthetic polymers are selected from the group consisting of homo polymers of vinyl alcohol, homo polymers of acrylamide, homo polymers of 2-amino-2-methyl propane sulfonic acid, copolymers thereof, and mixtures or combinations thereof, and
the partially hydrolyzed polymer and copolymers are selected from the group consisting of hydrolyzed or partially hydrolyzed polyacrylic acid, hydrolyzed or partially hydrolyzed polymethacrylic acid, hydrolyzed or partially hydrolyzed polyacrylamide, hydrolyzed or partially hydrolyzed copolymers of acrylic acid and one or more ethylenically unsaturated monomers, hydrolyzed or partially hydrolyzed copolymers of methyacrylic acid and one or more ethylenically unsaturated monomers, hydrolyzed or partially hydrolyzed copolymers of acrylamide and one or more ethylenically unsaturated monomers and mixtures or combinations thereof.

### Claim 8 (depends on 7)

The composition of claim 7, wherein the gel-forming hydratable polymers are selected from the group consisting of guars, derivatized guars, and mixtures or combinations thereof.

### Claim 9 (depends on 7)

The composition of claim 7, wherein:
the hydratable polymer composition comprises a mixture of a guar or derivatized guar and a polyacrylamide, and
the synthetic polymers and the friction reducer composition are adapted to reduce drag properties of the fluid composition and to improve a shear stability of the crosslinked structure formed in the fluid composition.

### Claim 10 (depends on 1)

The composition of claim 1, wherein:
the hydratable polymer composition is present in the slurry in an amount between about 1 gpt and about 10 gpt of the fracturing fluid composition.

### Claim 11 (depends on 10)

The composition of claim 10, wherein:
a ppt ratio of the one or more gel-forming hydratable polymers to the sum of the one or more synthetic polymers and partially hydrolyzed polymers and copolymers is between 4:1 to 4:3, and
the amount of the hydratable polymer composition in the slurry is between about 1 gpt and 2 gpt of the fracturing fluid composition.

### Claim 12 (depends on 1)

The composition of claim 1, wherein the crosslinking composition comprises one or more compounds including boron ions, zirconium ions, and titanium ions, or mixtures thereof.

### Claim 13 (depends on 12)

The composition of claim 12, wherein the crosslinking composition comprises one or more borate compounds.

### Claim 14 (depends on 1)

The composition of claim 1, wherein
the proppant comprises sand.

### Claim 15

A method of fracturing a subterranean formation comprising:
pumping a fracturing fluid composition into a tubular downhole injection mechanism, wherein the fracturing fluid composition comprising:
a base fluid comprising an elevated total dissolved solids (TDS) water selected from the group consisting of produced water, flow back water, brackish water, reverse osmosis (RO) reject water, clear brine, and mixtures and combinations thereof,
a hydratable polymer composition or a hydratable polymer slurry composition, wherein the hydratable polymer composition or hydratable polymer slurry composition includes one or more gel-forming hydratable polymers and one or more synthetic polymers, and
a friction reducer composition including hydrolyzed or partially hydrolyzed hydrolyzable polymers and copolymers, and
a cross-linking composition in an amount sufficient to crosslink the gel-forming hydratable polymer to form a fracturing fluid composition having a crosslinked structure so that the crosslinked structure occurs in the last 25% of a residence time in the tubular downhole injection mechanism,
wherein the hydratable polymer composition is present in an amount less than 10 ppt of the fracturing fluid composition and wherein the one or more synthetic polymers and the hydrolyzed or partially hydrolyzed hydrolyzable polymers and copolymers reduce drag properties of the fracturing fluid composition as the fracturing fluid composition travels down the tubular downhole injection mechanism into a subterranean formation and enters subterranean formation fractures.

### Claim 16 (depends on 15)

The method of claim 15, wherein, in the pumping step, the fracturing fluid composition further comprising:
a first buffer in an amount sufficient to adjust a pH of the fracturing fluid composition to an acidic pH to improve hydration of hydratable polymers and to prevent premature crosslinking of the gel-forming hydratable polymers, and
a second buffer in an amount sufficient to adjust the acidic pH to a final pH and to activate the crosslinking composition, wherein the final pH is at or above 9.

### Claim 17 (depends on 16)

The method of claim 16, wherein, in the pumping step, the acidic pH is less than or equal to pH 7.

### Claim 18 (depends on 17)

The method of claim 17, wherein, in the pumping step, the crosslinking composition is capable of producing the crosslinked structure at the acidic pH.

### Claim 19 (depends on 15)

The method of claim 15, wherein, in the pumping step, the fracturing fluid composition further comprising:
a buffer in an amount sufficient to adjust a pH of the fracturing fluid composition to a final pH sufficient to activate the crosslinking composition to form the crosslinked structure, wherein the final pH is at or above 9.

### Claim 20 (depends on 15)

The method of claim 15, wherein, in the pumping step, the base fluid further includes fresh water.

### Claim 21 (depends on 15)

The method of claim 15, further comprising:
adding a proppant to the fracturing fluid composition being pumped into the tubular downhole injection mechanism, wherein the pumping of the fracturing fluid composition into the subterranean formation generates long narrow fractures and wherein the crosslinked structure in the fracturing fluid composition improves proppant transport properties, reduces a fracturing fluid composition injection rate, and reduces a volume of water required to created a desired fracture geometry and a desired placement of the proppant into the fractures.

### Claim 22 (depends on 15)

The method of claim 15, wherein, in the pumping step:
the gel-forming hydratable polymers are selected from the group consisting of galactomannan gums, glucomannan gums, guars, derivatized guars, cellulose derivatives, and mixtures or combinations thereof,
the synthetic polymers are selected from the group consisting of homo polymers of vinyl alcohol, homo polymers of acrylamide, homo polymers of 2-amino-2-methyl propane sulfonic acid, copolymers thereof, and mixtures or combinations thereof,
the partially hydrolyzed polymer and copolymers are selected from the group consisting of hydrolyzed or partially hydrolyzed polyacrylic acid, hydrolyzed or partially hydrolyzed polymethacrylic acid, hydrolyzed or partially hydrolyzed polyacrylamide, hydrolyzed or partially hydrolyzed copolymers of acrylic acid and one or more ethylenically unsaturated monomers, hydrolyzed or partially hydrolyzed copolymers of methyacrylic acid and one or more ethylenically unsaturated monomers, hydrolyzed or partially hydrolyzed copolymers of acrylamide and one or more ethylenically unsaturated monomers and mixtures or combinations thereof, and
a ppt ratio of the one or more gel-forming hydratable polymers to the sum of the one or more synthetic polymers and partially hydrolyzed polymers and copolymers is between 4:1 to 4:3.

### Claim 23 (depends on 22)

The method of claim 22, wherein, in the pumping step, the gel-forming hydratable polymers are selected from the group consisting of guars, derivatized guars, and mixtures or combinations thereof.

### Claim 24 (depends on 22)

The method of claim 22, wherein, in the pumping step:
the hydratable polymer is a mixture of a guar or derivatized guar and a polyacrylamide, and
the synthetic polymers and the friction reducer composition reduce drag properties of the fracturing fluid as the fracturing fluid composition travels through the tubular downhole injection mechanism into a formation to be fractured and improve a shear stability of the crosslinked structure formed in the fracturing fluid composition.

### Claim 25 (depends on 24)

The method of claim 24, wherein, in the pumping step:
the hydratable polymer composition is present in the slurry in an amount between about 1 gpt and about 10 gpt.

### Claim 26 (depends on 25)

The method of claim 25, wherein, in the pumping step:
the amount of the hydratable polymer composition in the slurry is between about 1 gpt and 2 gpt.

### Claim 27 (depends on 15)

The method of claim 15, wherein, in the pumping step, the crosslinking composition comprises one or more compounds including metal ions including boron, zirconium, and titanium containing compounds, or mixtures thereof.

### Claim 28 (depends on 15)

The method of claim 15, wherein, in the pumping step, the crosslinking composition comprises one or more borate compounds.