Diverting agent and method of filling fracture in well using same

Patent metadata

Field	Value
Publication number	US-11674073-B2
Application number	US-202117397244-A
Country	US
Kind code	B2
Filing date	Aug 9, 2021
Priority date	Feb 13, 2019
Publication date	Jun 13, 2023
Grant date	Jun 13, 2023

Abstract

A diverting agent of the present invention contains a polyvinyl alcohol-based resin, wherein when the diverting agent is added to a 0.48 mass % aqueous solution of guar gum to prepare a mixed solution having a concentration of 12 mass %, a dispersion liquid obtained by dispersing the mixed solution at 30° C. for 60 minutes is pressurized and dehydrated at a pressure of 1 MPa using a pressure dehydration device including a drainage part having a slit having a width of 2 mm, and a regression line represented by an equation (A): y=ax+b (in the equation (A), y is a cumulative dehydration amount (g), x is a square root of a time (minutes) elapsed from start of pressurization, a and b are a slope and an intercept of the regression line, respectively, and 0<x≤2) is calculated by a least squares method from a scatter diagram plotted on a graph in which the square root x of the time is plotted on a horizontal axis and the cumulative dehydration amount y is plotted on a vertical axis, a slope a of the equation (A) satisfies a condition (B): a≤80.

First claim

The invention claimed is:

1. A diverting agent, comprising:
a polyvinyl alcohol-based resin, wherein
when the diverting agent is added to a 0.48 mass % aqueous solution of guar gum to prepare a mixed solution having a concentration of 12 mass % of the diverting agent, the mixed solution is dispersed at 30° C. for 60 minutes to obtain a dispersion liquid, the dispersion liquid is pressurized and dehydrated at a pressure of 1 MPa using a pressure dehydration device including a drainage part having a slit having a width of 2 mm, a cumulative dehydration amount y with respect to a square root x of a time is obtained, and a regression line represented by the following equation (A) is calculated by a least squares method from a scatter diagram plotted on a graph in which the square root x of the time is plotted on a horizontal axis and the cumulative dehydration amount y is plotted on a vertical axis, a slope a of the equation (A) satisfies the following condition (B)
y=ax+b   (A)

a≤ 80  (B)

wherein in the equation (A), y is the cumulative dehydration amount, x is the square root of the time in minutes elapsed from start of pressurization, a and b are the slope and an intercept of the regression line, respectively, and 0<x≤2.

2. The diverting agent according to claim 1 , wherein the polyvinyl alcohol-based resin contains two or more types of resin particles that are in the form of particles and have different average particle diameters.

3. The diverting agent according to claim 1 , wherein the polyvinyl alcohol-based resin contains a modified polyvinyl alcohol-based resin.

4. A method for preparing a diverting agent for temporarily filling a fracture generated in a well, the method comprising:
incorporating a polyvinyl alcohol-based resin, wherein
when the diverting agent is added to a 0.48 mass % aqueous solution of guar gum to prepare a mixed solution having a concentration of 12 mass % of the diverting agent, the mixed solution is dispersed at 30° C. for 60 minutes to obtain a dispersion liquid, the dispersion liquid is pressurized and dehydrated at a pressure of 1 MPa using a pressure dehydration device including a drainage part having a slit having a width of 2 mm, a cumulative dehydration amount y with respect to a square root x of a time is obtained, and a regression line represented by the following equation (A) is calculated by a least squares method from a scatter diagram plotted on a graph in which the square root x of the time is plotted on a horizontal axis and the cumulative dehydration amount y is plotted on a vertical axis, a slope a of the equation (A) satisfies the following condition (B)
y=ax+b   (A)

a≤ 80  (B)

wherein in the equation (A), y is the cumulative dehydration amount, x is the square root of the time in minutes elapsed from start of pressurization, a and b are the slope and an intercept of the regression line, respectively, and 0<x≤2.

5. A method of temporarily filling a fracture generated in a well, the method comprising:
allowing the diverting agent according to claim 1 to flow into a fracture with a flow of a fluid in the well.

Assignees

• Mitsubishi Chem Corp

Inventors

• Mandai Shusaku
• Hirano Yasuhiro
• Taniguchi Ryosuke
• Furo Chizuko
• Furui Kenji
• Shinohara Kenji
• Sato Ken

Classifications

• C09K8/035 Primary

  Organic additives · CPC title

• C08F216/06

  Polyvinyl alcohol {; Vinyl alcohol} · CPC title

• C08K5/098

  Metal salts of carboxylic acids · CPC title

• C08L2205/03

  containing three or more polymers in a blend · CPC title

• C08L29/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title