Nano-indentation test to determine mechanical properties of reservoir rock

Patent metadata

Field	Value
Publication number	US-10451601-B2
Application number	US-201715625811-A
Country	US
Kind code	B2
Filing date	Jun 16, 2017
Priority date	Jun 28, 2016
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

Nano-indentation test to determine mechanical properties of reservoir rock can be implemented as multi-stage or single-stage tests. An experimental nano-indentation test (multi-stage or single-stage) is performed on a solid sample. A numerical nano-indentation test (multi-stage or single-stage) is performed on a numerical model of the solid sample. One or more experimental force-displacement curves obtained in response to performing the experimental nano-indentation test and one or more numerical force-displacement curves obtained in response to performing the numerical test are compared. Multiple mechanical properties of the solid sample are determined based on a result of the comparing.

First claim

What is claimed is:

1. A method comprising:
performing an experimental multi-stage nano-indentation test on a shale rock sample by:
in a first stage:
indenting, using a nano-indenter, the shale rock sample to a first depth from a surface of the sample, and
withdrawing the nano-indenter to a second depth from the surface of the shale rock sample, the second depth less than the first depth;

in a second stage:
indenting, using the nano-indenter, the shale rock sample to a third depth greater than the first depth, and
withdrawing the nano-indenter to a fourth depth from the surface of the shale rock sample, the fourth depth less than the third depth; and

during the first stage and the second stage, measuring a load on the shale rock sample during the indenting and the withdrawing;

performing a numerical multi-stage nano-indentation test on a numerical model of the shale rock sample, wherein the numerical multi-stage nano-indentation test matches the experimental multi-stage nano-indentation test;
comparing a plurality of experimental force-displacement curves obtained in response to performing the experimental multi-stage nano-indentation test and a plurality of numerical force-displacement curves obtained in response to performing the numerical multi-stage test; and
determining a plurality of mechanical properties of the shale rock sample based on a result of the comparing.

2. The method of claim 1 , wherein the shale rock sample is substantially 10 mm long, substantially 5 mm wide and substantially 3 mm thick.

3. The method of claim 1 , wherein performing the experimental multi-stage nano-indentation test on the shale rock sample comprises:
in a first stage,
indenting the shale rock sample with a first load, and
unloading the first load to a second load less than the first load; and

in a second stage,
indenting the shale rock sample with a third load greater than the first load, and
unloading the third load to a fourth load less than the third load.

4. The method of claim 3 , further comprising:
in a third stage,
indenting the shale rock sample with a fifth load greater than the third load, and
unloading the fifth load to a sixth load less than the fifth load.

5. The method of claim 4 , wherein the third load is greater than the second load, wherein the fifth load is greater than the fourth load, wherein the second load is less than the fourth load, and wherein the fourth load is less than the sixth load.

6. The method of claim 4 , wherein the first load is about 100 milli-Newtons (mN), the second load is about 30 mN, the third load is about 250 mN, the fourth load is about 120 mN, the fifth load is about 400 mN and the sixth load is about 120 mN.

7. The method of claim 1 , further comprising:
in a third stage:
indenting, using the nano-indenter, the shale rock sample to a fifth depth greater than the third depth,
withdrawing the nano-indenter to a sixth depth from the surface of the shale rock sample, the sixth depth less than the fifth depth, and
during the third stage, measuring a load on the shale rock sample during the indenting and the withdrawing.

8. The method of claim 7 , wherein a depth to which the nano-indenter indents the surface of the shale rock sample is at most 1/10 th of a thickness of the shale rock sample.

9. The method of claim 1 , wherein performing the numerical multi-stage nano-indentation test on the numerical model of the shale rock sample comprises:
numerically modeling a nano-indenter to perform the experimental nano-scale indentation test on the shale rock sample;
numerically modeling the shale rock sample; and
numerically modeling each stage of the experimental multi-stage nano-indentation test by indenting the numerically modeled shale rock sample with the numerically modeled nano-indenter.

10. The method of claim 9 , wherein the shale rock sample is numerically modeled based on mechanical properties of individual components of the shale rock sample.

11. The method of claim 9 , wherein the mechanical properties comprise a cohesive strength, a friction angle and a tensile strength.

12. The method of claim 9 , wherein the mechanical properties of the individual components based on which the shale rock sample is numerically modeled comprises Young's modulus, Poisson's ratio, cohesive strength, frictional angle and tensile strength.

13. The method of claim 1 , wherein comparing the plurality of experimental force-displacement curves obtained in response to performing the experimental multi-stage nano-indentation test and the plurality of numerical force-displacement curves obtained in response to performing the numerical multi-stage test comprises comparing each force-displacement curve obtained in response to performing each experimental stage to each force-displacement curve obtained in response to performing each numerical stage.

14. The method of claim 13 , determining a plurality of mechanical properties of the shale rock sample based on a result of the comparing comprises:
determining that the plurality of experimental force-displacement curves match the plurality of numerical force-displacement curves;
identifying mechanical properties of the individual components based on which the shale rock sample was numerically modeled; and
determining that the plurality of the mechanical properties of the shale rock sample match the mechanical properties based on which the shale rock sample was numerically modeled.

15. The method of claim 14 , wherein determining that the plurality of experimental force-displacement curves match the plurality of numerical force-displacement curves comprises determining that a variance between each experimental force-displacement curve and each corresponding numerical force-displacement curve is less than 5%.

16. The method of claim 1 , wherein determining a plurality of mechanical properties of the shale rock sample based on a result of the comparing comprises:
determining that at least one of the plurality of experimental force-displacement curves does not match a corresponding numerical force-displacement curve; and
modifying mechanical properties of the individual components based on which the shale rock sample was numerically modeled.

Assignees

• Saudi Arabian Oil Co

Inventors

• Han Yanhui
• Abousleiman Younane N
• Hull Katherine Leigh
• Muntasheri Ghaithan

Classifications

• G01N2203/0216

  Finite elements · CPC title

• G01N2203/0218

  Calculations based on experimental data · CPC title

• G01N3/42

  by performing impressions under a steady load by indentors, e.g. sphere, pyramid (G01N3/54 takes precedence) · CPC title

• E21B49/02

  by mechanically taking samples of the soil · CPC title

• G01N33/24 Primary

  Earth materials (G01N33/42 takes precedence) · CPC title