Method for measuring the diffusion coefficient of water within a porous medium by a nuclear magnetic resonance method

Patent metadata

Field	Value
Publication number	US-11226275-B2
Application number	US-201816621587-A
Country	US
Kind code	B2
Filing date	May 15, 2018
Priority date	Jun 19, 2017
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

The present invention relates to a method of measuring the diffusion coefficient of water in a porous medium. The coefficient is measured using a nuclear magnetic resonance (NMR) technique (2, 3, 4) and the sample (1) has the shape of a hollow cylinder.

First claim

The invention claimed is:

1. A method of measuring a diffusion coefficient of water in a porous medium, comprising:
a) preparing a sample of the porous medium which is shaped as a hollow cylinder that only contains liquid during measurement of the diffusion coefficient with an inside diameter of the hollow cylinder ranging between 15 and 30% of an outside diameter of the hollow cylinder;
b) saturating the sample of the porous medium with water;
c) immersing the water-saturated sample of the porous medium in a water-miscible tracer fluid which is not detectable by a Nuclear Magnetic Resonance (NMR) method;
d) measuring the water concentration in the sample using an NMR method; and
e) determining the water diffusion coefficient in the porous medium by use of the measured water concentration in the sample which accounts for the shape of the hollow cylinder during measurement of the sample of the porous medium.

2. A method as claimed in claim 1 , wherein the porous medium is one of a cement paste, concrete or rock.

3. A method as claimed in claim 2 , wherein the concrete contains aggregates sized in millimeters.

4. A method as claimed in claim 3 , wherein an outside diameter of the hollow cylinder ranges between 20 and 80 mm, and an inside diameter of the hollow cylinder ranges between 2 and 25 mm.

5. A method as claimed in claim 2 , wherein an outside diameter of the hollow cylinder ranges between 20 and 80 mm, and an inside diameter of the hollow cylinder ranges between 2 and 25 mm.

6. A method as claimed in claim 2 , wherein the tracer fluid which is not detectable by the NMR method is deuterium.

7. A method as claimed in claim 2 , comprising:
double coring the porous medium.

8. A method as claimed in claim 1 , wherein an outside diameter of the hollow cylinder ranges between 20 and 80 mm, and an inside diameter of the hollow cylinder ranges between 2 and 25 mm.

9. A method as claimed in claim 8 , wherein the tracer fluid which is not detectable by the NMR method is deuterium.

10. A method as claimed in claim 8 , comprising:
double coring the porous medium.

11. A method of storing a radioactive material in an enclosure, comprising:
a) determining a water diffusion coefficient within cement pastes by use of the diffusion coefficient measurement method as claimed in claim 8 ;
b) constructing the enclosure with a cement paste having a lowest diffusion coefficient of an available cement paste; and
c) storing the radioactive material within the cement enclosure.

12. A method as claimed in claim 1 , wherein the tracer fluid which is not detectable by the NMR method is deuterium.

13. A method as claimed in claim 12 , comprising:
double coring the porous medium.

14. A method as claimed in claim 1 , comprising:
double coring the porous medium.

15. A method of storing a radioactive material in an enclosure, comprising:
a) determining a water diffusion coefficient within available cement pastes by use of the diffusion coefficient measurement method as claimed in claim 14 ;
b) constructing the enclosure with a cement paste having a lowest diffusion coefficient of cement paste; and
c) storing the radioactive material within the cement enclosure.

16. A method as claimed in claim 1 , wherein the diffusion coefficient D p of the water in the porous medium is determined by a formula:

C
*

=

C

p
⁢

⁢
s

⁢

C
cylcreux

C

p
⁢

⁢
s

=

∑

n
=
0

∞

⁢

8

(

2
⁢
n

+
1

)

2

⁢

π
2

⁢

exp
⁡

(

-

D
p

⁡

(

2
⁢
n

+
1

)

2

⁢

π
2

⁢

t

4
⁢

⁢

l
2

)

,

⁢

C
cylcreux

=

4

b
2

-

Assignees

• Ifp Energies Now

Inventors

• Fleury Marc

Classifications

• G01N2013/003

  Diffusion; diffusivity between liquids · CPC title

• G01N24/081

  Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity · CPC title

• G01N33/383

  Concrete or cement · CPC title

• G01N13/00 Primary

  Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects (scanning-probe techniques or apparatus G01Q) · CPC title

• G01N24/08

  by using nuclear magnetic resonance (G01N24/12 takes precedence) · CPC title