Thinner for oil-based drilling fluids

Patent metadata

Field	Value
Publication number	US-10723931-B2
Application number	US-201514945697-A
Country	US
Kind code	B2
Filing date	Nov 19, 2015
Priority date	Nov 19, 2015
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

A thinner that is a polycondensed fatty acid that is selected from the group consisting of 12-hydroxystearic acid, 12-hydroxyoctadecanoic acid, polyhydroxystearic acid, reaction products with stearic acid, octadecanoate, octadecanoic acid, and homopolymers of stearic acid is able to reduce the viscosity of oil-based drilling fluid, thus allowing for reuse of the oil-based drilling fluid.

First claim

What is claimed is:

1. A method of decreasing viscosity of an oil-based drilling fluid composition comprising
a) Adding a thinner to the oil-based drilling fluid to form an oil-based drilling fluid composition; wherein the thinner is 0.03-0.2% of a polycondensed fatty acid that is selected from the group consisting of 12-hydroxystearic acid, polyhydroxystearic acid, stearic acid, reaction products with stearic acid, salts containing octadecanoate anion, homopolymers of stearic acid, fatty imidazoline (Z)-4-((2-(2-((E)-heptadec-8-en-1-yl)-4,5-dihydro-1H-imidazol-1-yl)ethyl)amino)-4-oxobut-2-enoic acid and mixtures thereof; wherein the molecular weight of the thinner is 600-2.4 kilodaltons;
b) injecting the oil-based drilling fluid composition into a wellbore; and
c) retrieving the oil-based drilling fluid composition as it returns to the surface.

2. The method of claim 1 wherein steps a)-c) are repeated.

3. The method of claim 1 wherein the temperature of the wellbore is 180 degrees C. or less.

4. The method of claim 1 wherein the temperature of the wellbore is 130 degrees C. or less.

5. The method of claim 1 wherein the temperature of the wellbore is 22 degrees C. or above.

6. The method of claim 1 wherein viscosity of the oil-based drilling fluid composition after addition of the thinner is decreased by up to 75% of the yield point in comparison to viscosity of the oil-based drilling fluid before addition of the thinner.

7. The method of claim 1 wherein viscosity of the oil-based drilling fluid composition after addition of the thinner is decreased by up to 50% of the yield point in comparison to viscosity of the oil-based drilling fluid before addition of the thinner.

8. The method of claim 1 wherein the oil-based drilling fluid comprises
50-100% oil base;
1-5% viscosifier;
20-70% weighting agent;
5-10% fluid loss additives;
0-5% lime;
0-30% brine; and
0.3-10% emulsifiers.

Assignees

• Cnpc Usa Corp

Inventors

• Zhou Chun
• Liu Fuchen
• Hoxha Burhan

Classifications

• C09K8/32 Primary

  Non-aqueous well-drilling compositions, e.g. oil-based · CPC title

• E21B21/062

  by mixing components · CPC title

• C09K2208/28

  Friction or drag reducing additives · CPC title

• C09K8/36

  Water-in-oil emulsions · CPC title

• C09K8/035 Primary

  Organic additives · CPC title