Method for determining the viscosity of a polymer solution

Patent metadata

Field	Value
Publication number	US-11841302-B2
Application number	US-201917432009-A
Country	US
Kind code	B2
Filing date	Feb 19, 2019
Priority date	Feb 19, 2019
Publication date	Dec 12, 2023
Grant date	Dec 12, 2023

Abstract

The invention relates to a method for determining the intrinsic viscosity [η] of an aqueous polymer solution at a temperature T, wherein the aqueous polymer solution comprises at least one acrylamide-based polymer in an aqueous solvent, the aqueous solvent having a salinity of from 6 to 250 g/L, the method comprising the steps of: —providing a single universal relation R 1 between (i), the product of polymer concentration and intrinsic viscosity C·[η], and (ii) specific viscosity at zero shear rate η sp ; —performing a measurement of the dynamic viscosity of the aqueous polymer solution at one polymer concentration C 1 , at temperature T and at various shear rates; —determining from said measurement the zero-shear viscosity η 0 of the aqueous polymer solution at polymer concentration C 1 and at temperature T; —calculating the specific viscosity at zero shear rate of the aqueous polymer solution at polymer concentration C and at temperature T as η sp =(η 0 −η s )/η s , where η s is the zero-shear viscosity of the aqueous solvent; —estimating the intrinsic viscosity [η] of the aqueous polymer solution at temperature T by applying the universal relation R 1 to the calculated specific viscosity at zero shear rate η sp and polymer concentration C 1 .

First claim

The invention claimed is:

1. A method for determining intrinsic viscosity [η] of an aqueous polymer solution at a temperature T, wherein the aqueous polymer solution comprises at least one acrylamide-based polymer in an aqueous solvent, the aqueous solvent having a salinity of from 6 to 250 g/L, the method comprising:
providing a single universal relation R 1 between (i), product of polymer concentration and intrinsic viscosity C·[η], and (ii) specific viscosity at zero shear rate η sp ;
performing a measurement of dynamic viscosity of the aqueous polymer solution at one polymer concentration C 1 , at temperature T and at various shear rates;
determining from said measurement zero-shear viscosity η 0 of the aqueous polymer solution at polymer concentration C 1 and at temperature T;
calculating specific viscosity at zero shear rate of the aqueous polymer solution at polymer concentration C 1 and at temperature T as η sp =(η 0 −η s )/η s , where η s is zero-shear viscosity of the aqueous solvent; and
estimating the intrinsic viscosity [η] of the aqueous polymer solution at temperature T by applying the universal relation R 1 to the calculated specific viscosity at zero shear rate η sp and polymer concentration C 1 .

2. The method according to claim 1 , wherein one or more measurements of the dynamic viscosity of the aqueous polymer solution at various shear rates are performed only at the polymer concentration C 1 .

3. The method according to claim 1 , further comprising:
performing a measurement of dynamic viscosity of the aqueous polymer solution, at at least another polymer concentration C 2 , at temperature T, and at various shear rates;
determining zero-shear viscosity η 0 of the aqueous polymer solution at least the polymer concentrations C 1 and C 2 and at temperature T, from the measurement of the dynamic viscosity of the aqueous polymer solution at the polymer concentration C 1 and the measurement of the dynamic viscosity of the aqueous polymer solution at the polymer concentration C 2 ;
calculating specific viscosity at zero shear rate of the aqueous polymer solution at least the polymer concentrations C 1 and C 2 and at temperature T as η sp =(η 0 −η s )/η s , where η s is the zero-shear viscosity of the aqueous solvent; and
estimating an average intrinsic viscosity [η] of the aqueous polymer solution at temperature T by fitting the calculated specific viscosity at zero shear rate of the aqueous polymer solution at least the polymer concentrations C 1 and C 2 and at temperature T with the universal relation R 1 .

4. The method according to claim 1 , wherein the single universal relation R 1 is obtained by:
providing a number of acrylamide-based polymers;
for each acrylamide-based polymer, performing several measurements of dynamic viscosity of aqueous solutions of the acrylamide-based polymer in an aqueous solvent, the aqueous solvent having a salinity of from 6 to 250 g/L, at various shear rates and various polymer concentrations, at one or several temperatures;
deriving specific viscosity at zero shear rate and intrinsic viscosity of each aqueous solution, at each concentration and temperature, from said several measurements, so as to obtain a set of specific viscosity at zero shear rate data associated with product of intrinsic viscosity and polymer concentration data; and
providing a mathematical fit for the specific viscosity at zero shear rate data as a function of the product of intrinsic viscosity and polymer concentration data.

5. The method according to claim 1 , wherein the single universal relation R 1 is defined as η sp =C·[η]+0.56 (C·[η]) 2.17 +0.0026 (C·[η]) 4.72 or as any other function where η sp deviates from C·[η]+0.56 (C·[η]) 2.17 +0.0026 (C·[η]) 4.72 at any value of C·[η] by less than 20%.

6. A method for determining dynamic viscosity of an aqueous polymer solution as a function of shear rate, at a temperature T and at a polymer concentration C′, wherein the aqueous polymer solution comprises at least one acrylamide-based polymer in an aqueous solvent, the aqueous solvent having a salinity of from 6 to 250 g/L, the method comprising:
providing a single universal relation R 2 between (i) product of polymer concentration and intrinsic viscosity C·[η] and (ii) Carreau coefficient n;
providing a single universal relation R 3 between (i) the product of polymer concentration and intrinsic viscosity C·[η] and (ii) ratio of relaxation time to diluted regime-relaxation time λ/λ d ;
determining intrinsic viscosity [η] of the aqueous polymer solution at temperature T by:
providing a single universal relation R 1 between (i), the product of polymer concentration and intrinsic viscosity C·[η], and (ii) specific viscosity at zero shear rate η sp ;
performing a measurement of dynamic viscosity of the aqueous polymer solution at one or more polymer concentrations other than C′, at temperature T and at various shear rates;
determining from said measurement zero-shear viscosity η 0 of the aqueous polymer solution at the one or more polymer concentrations other than C′ and at temperature T;
calculating specific viscosity at zero shear rate of the aqueous polymer solution at the one or more polymer concentrations other than C′ and at temperature T as η sp =(η 0 −η s )/η s , where η s is zero-shear viscosity of the aqueous solvent; and
estimating the intrinsic viscosity [η] of the aqueous polymer solution at temperature T by applying the universal relation R 1 to the calculated specific viscosity at zero shear rate η sp and the one or more polymer concentrations other than C′;

estimating diluted regime-relaxation time λ d of the aqueous polymer solution at temperature T by:
determining relaxation time λ 1 of the aqueous polymer solution at temperature T and at a single polymer concentration C 1 , from a measurement of dynamic viscosity of the aqueous polymer solution at polymer concentration C 1 and at temperature T, and then applying the universal relation R 3 to the determined relaxation time λ 1 , polymer concentration C 1 and the determined intrinsic viscosity [η] at temperature T; or
determining at least two relaxation times λ 1 and λ 2 of the aqueous polymer solution at temperature T and at at least two respective polymer concentrations C 1 and C 2 , from respective measurements of dynamic viscosity of the aqueous polymer solution at the at least two polymer concentrations C 1 and C 2 and at temperature T, and applying the universal relation R 3 to the at least two determined relaxation times λ 1 and λ 2 , respective polymer concentrations C 1 and C 2 and the determined intrinsic viscosity [η] at temperature T so as to provide an average value of λ d at temperature T;

estimating relaxation time λ′ of the aqueous polymer solution at temperature T and polymer concentration C′ by applying the universal relation R 3 to the estimated diluted-regime relaxation time λ d , the polymer concentration C′ and the determined intrinsic viscosity [η] at temperature T;
estimating Carreau coefficient n′ of the aqueous polymer solution at temperature T and polymer concentration C′ by applying the universal relation R 2 to polymer concentration C′ and the determined intrinsic viscosity [η] at temperature T;
estimating specific viscosity at zero shear rate η sp ′ of the aqueous polymer solution at polymer concentration C′ and at temperature T by applying the universal relation R 1 to (i) the determined intrinsic viscosity [η] at temperature T and (ii) polymer concentration C′;
estimating a zero-shear viscosity η 0 ′ of the aqueous polymer solution at polymer concentration C′ and at temperature T as η 0 ′=η s ·(η sp ′+1); and
estimating the dynamic viscosity η′ of the aqueous polymer solution as a function of shear rate {dot over (γ

Assignees

• Total Se

Inventors

• Jouenne Stéphane
• Levache Bertrand

Classifications

• G01N11/02 Primary

  by measuring flow of the material · CPC title

• G01N33/442

  Resins; Plastics · CPC title

• G01N2011/004

  Stress relaxation time · CPC title

• G01N2011/0033

  Yield stress; Residual stress at zero shear rate · CPC title

• G01N11/00 Primary

  Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties · CPC title