# US 2019/0169480 A1 · Aqueous drilling fluid for reducing bitumen accretion

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- Number: US 2019/0169480 A1
- Document ID: US20190169480A1
- Status: Published application
- Kind: A1
- Application number: 16/210,268
- Filed: 2018-12-05
- Published: 2019-06-06
- Earliest claimed: 2017-12-05
- Assignees: Secure Energy (Drilling Services) Inc.
- Applicants: Secure Energy (Drilling Services) Inc.
- Inventors: Kuangbiao MA; Stuart DUBBERLEY
- Web page: https://patentgrep.com/patent/US20190169480A1

## CPC

- C08F 220/56: Acrylamide; Methacrylamide
- C09K 8/04: Aqueous well-drilling compositions
- C09K 8/12: containing synthetic organic macromolecular compounds or their precursors
- C09K 8/524: organic depositions, e.g. paraffins or asphaltenes
- E21B 37/06: using chemical means for preventing or limiting {, e.g. eliminating,} the deposition of paraffins or like substances
- C08F 2800/20: as weight or mass percentages
- E21B 21/062: {by mixing components}
- E21B 21/065: {Separating solids from drilling fluids}
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- 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

Some embodiments of the present disclosure relate to drilling fluids that comprise an aqueous solvent and an ampholytic semi-hydrophobic polymer that is readily hydratable under field mixing conditions. The ampholytic semi-hydrophobic polymer comprises semi-hydrophobic monomer units comprising a C1-C7 hydrocarbyl substituent, a hydrogen substituent, or a combination thereof. Some embodiments of the present disclosure relate to use of a drilling fluid as defined herein to reduce bitumen accretion to a wellbore drilling component. Some embodiments of the present disclosure relate to methods for reducing bitumen accretion to a wellbore drilling component, the method comprising introducing a drilling fluid as defined herein into a wellbore containing the wellbore drilling component.

## Claims

### Claim 1

A drilling fluid comprising:
an aqueous solvent; and
an ampholytic semi-hydrophobic polymer that is hydratable under field mixing conditions,
wherein the ampholytic semi-hydrophobic polymer comprises a semi-hydrophobic monomer unit that comprises a C1-C7 hydrocarbyl substituent, a hydrogen substituent, or a combination thereof.

### Claim 2 (depends on 1)

The drilling fluid of claim 1, wherein the semi-hydrophobic monomer units are present in the ampholytic hydrophobic polymer in an amount of less than about 10% (w/w).

### Claim 3 (depends on 1)

The drilling fluid of claim 1, wherein the C1-C7 hydrocarbyl substituent is one of a C4-C7 alkyl substituent, a C4-C7 alkenyl substituent, a C4-C7 alkynyl substituent, and a combination thereof.

### Claim 4 (depends on 1)

The drilling fluid of claim 1, wherein the semi-hydrophobic monomer unit comprises a cationic semi-hydrophobic monomer units.

### Claim 5 (depends on 4)

The drilling fluid of claim 4, wherein the cationic semi-hydrophobic monomer unit comprises a quaternary ammonium substituent.

### Claim 6 (depends on 4)

The drilling fluid of claim 4, wherein the cationic semi-hydrophobic monomer units are as shown in formula (I) or formula (II):
wherein n is an integer between 1 and about 300,000, and wherein R, R′, R″, and R′″ are each independently a C1-C7 alkyl substituent, a C2-C7 alkenyl substituent, a C2-C7 alkynyl substituent, and a hydrogen substituent.

### Claim 7 (depends on 6)

The drilling fluid of claim 6, wherein R, R′, R″, and R′″ are each independently a C4-C7 alkyl substituent, a C4-C7 alkenyl substituent, and a C4-C7 alkynyl substituent.

### Claim 8 (depends on 1)

The drilling fluid of claim 1, wherein the ampholytic semi-hydrophobic polymer further comprises anionic monomer units and non-ionic monomer units.

### Claim 9 (depends on 8)

The drilling fluid of claim 8, wherein the anionic monomer units are acrylate monomer units.

### Claim 10 (depends on 8)

The drilling fluid of claim 8, wherein the non-ionic monomer units are acrylamide monomer units.

### Claim 11 (depends on 1)

The drilling fluid of claim 1, wherein between about 2% and about 4% (w/w) of the ampholytic semi-hydrophobic polymer is comprised of a cationic semi-hydrophobic monomer unit.

### Claim 12 (depends on 1)

The drilling fluid of claim 1, wherein between about 10% and about 20% (w/w) of the ampholytic semi-hydrophobic polymer is comprised of an anionic monomer unit.

### Claim 13 (depends on 1)

The drilling fluid of claim 1, wherein between about 75% and about 95% (w/w) of the ampholytic semi-hydrophobic polymer is comprised of a non-ionic monomer unit.

### Claim 14 (depends on 1)

The drilling fluid of claim 1, wherein the semi-hydrophobic monomer units are each an anionic semi-hydrophobic monomer unit.

### Claim 15 (depends on 1)

The drilling fluid of claim 1, wherein the semi-hydrophobic monomer unit is a non-ionic semi-hydrophobic monomer unit.

### Claim 16

A method for reducing bitumen accretion on a wellbore drilling component, the method comprising introducing a drilling fluid into a wellbore containing the wellbore drilling component, wherein the drilling fluid comprises:
an aqueous solvent; and
an ampholytic semi-hydrophobic polymer that is hydratable under field mixing conditions, wherein the ampholytic semi-hydrophobic polymer comprises semi-hydrophobic monomer units comprising a C1-C7 hydrocarbyl substituent, a hydrogen substituent, or a combination thereof.

### Claim 17 (depends on 1)

A method for reducing bitumen accretion on a wellbore drilling component, the method comprising introducing the drilling fluid defined in claim 1 into a wellbore containing the wellbore drilling component.

### Claim 18 (depends on 16)

The method of claim 16, wherein the drilling fluid is circulated through the wellbore.

### Claim 19 (depends on 17)

The method of claim 17, wherein the drilling fluid is circulated through the wellbore.

### Claim 20 (depends on 18)

The method of claim 18, further comprising separating drill cuttings from the drilling fluid.