Organic-inorganic nanocomposite gel and oil-based drilling fluid

Patent metadata

Field	Value
Publication number	US-11753575-B2
Application number	US-202217802545-A
Country	US
Kind code	B2
Filing date	Jun 16, 2022
Priority date	Jun 22, 2021
Publication date	Sep 12, 2023
Grant date	Sep 12, 2023

Abstract

The invention discloses an organic-inorganic nanocomposite gel sealing agent and oil-based drilling fluid. The sealing agent used for the oil-based drilling fluid is organic-inorganic nanocomposite gel, and the synthetic raw materials of the organic-inorganic nanocomposite gel includes molybdenum disulfide, 2-ethyl acrylic acid, N, N-dimethylacrylamide and N,N-methylene bisacrylamide; the drilling fluid includes the organic-inorganic nanocomposite gel provided by the invention. The organic-inorganic nanocomposite gel is used as a nano sealing agent, the particle size distribution of the organic-inorganic nanocomposite gel is 50-200 nm, the organic-inorganic nanocomposite gel can effectively prevent drilling fluid filtrate from intruding into stratums and prevent accidents such as borehole wall collapse, the organic-inorganic nanocomposite gel is particularly suitable for nano-sealing of shale stratums, and the preparation method of the organic-inorganic nanocomposite gel is reliable in principle and has a wide market prospect.

First claim

What is claimed is:

1. A method for preparing an organic-inorganic nanocomposite gel sealing agent, comprising the following steps:
(1) modification of nano-molybdenum disulfide: place nano-molybdenum disulfide in 75-80° C. vacuum drying tank for 10-12 h to dry, add 2-3 g of the dry nano-molybdenum disulfide to 40-50 ml of ethanol/water to form a dispersion, ultrasonicate for 40-50 min, then add 2-3 g of 3-aminopropyltriethoxysilane while stirring, react 8-10 h at 75-80° C., wash with ethanol and repeat 3-5 times before placing in 55-60° C. vacuum drying tank for 8-10 h to obtain modified nano-molybdenum disulfide;
(2) preparation of the organic-inorganic nanocomposite gel:
{circle around (1)} add the modified molybdenum disulfide to a reactor with ultra-pure water and ultrasound for 10-15 min to form a dispersion;
{circle around (2)} add comonomer of 2-ethyl acrylic acid and N, N-dimethylacrylamide, crosslinker of N, N-methylene bisacrylamide, stir rapidly to dissolve under nitrogen 20-30 min;
{circle around (3)} warm the reaction system to 55-60° C. while stirring, add ammonium persulphate and keep at a constant reaction temperature for 3-4 h;
{circle around (4)} after the reaction is completed, the temperature is reduced to 20-25° C., and the prepared sample is washed with distilled water to neutral, then dried in 60-70° C. oven;
{circle around (5)} grind the dried sample.

2. The method for preparing the organic-inorganic nanocomposite gel sealing agent according to claim 1 , wherein the amount of the modified nano molybdenum disulfide is 5-15% of the total weight of 2-ethyl acrylic acid and N, N-dimethylacrylamide; the amount of 2-ethyl acrylic acid is in the range of 3-3.5 g; 2-ethyl acrylic acid and N, N-dimethylacrylamide are in the weight ratio in the range of 1:1 to 1.5; the amount of N, N-methylene bisacrylamide is in the range of 1% to 3%; and the amount of ammonium persulphate is in a range of 1% to 3%.

3. An oil-based drilling fluid, wherein the drilling fluid comprises an organic-inorganic nanocomposite gel sealing agent prepared according to the method of claim 1 or claim 2 .

4. The oil-based drilling fluid according to claim 3 , wherein the drilling fluid includes the following components: 70-100 parts of white oil, 0.5-1 part of main emulsifier, 1-3 parts of serial dilutifiers, 5-10 parts of filter loss reducing agent, 2-5 parts of organic soil, 0.5-5 parts of quicklime, 10-30 parts of CaCl 2 brine with 20-25% concentration of CaCl 2 , 0.5-2 parts of wetting agent, 10-30 parts of heavy crystal stones, and 1-5 parts of the organic-inorganic nanocomposite gel sealing agent.

5. The oil-based drilling fluid according to claim 4 , wherein the filter loss reducing agent is oxidation asphalt, and a density of the heavy crystal stone is 4.2 g/cm 3 .

6. The oil-based drilling fluid according to claim 4 , wherein a pH of the oil-based drilling fluid is in the range of 8.5 to 10.

7. The oil-based drilling fluid according to claim 4 , wherein the oil-based drilling fluid has a density in the range of 1.20-2.20 g/cm 3 before adding the organic-inorganic nanocomposite gel sealing agent.

Assignees

• Univ Southwest Petroleum

Inventors

• Xie Gang
• Wang Ruolan
• Huang Jinjun
• Bai Yang

Classifications

• C09K8/512 Primary

  containing cross-linking agents · CPC title

• C09K8/035 Primary

  Organic additives · CPC title

• C09K8/5083

  obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• C09K8/32

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

• C08F220/04

  Acids; Metal salts or ammonium salts thereof · CPC title