Kerogen maturity and porosity in shale

Patent metadata

Field	Value
Publication number	US-2021140902-A1
Application number	US-201816491987-A
Country	US
Kind code	A1
Filing date	Mar 7, 2018
Priority date	Mar 7, 2017
Publication date	May 13, 2021
Grant date	—

Abstract

A system having an NMR measurement device make measurements on a region of investigation in which an NMR-active fluid has been injected. A source of the NMR-active fluid (e.g., methane) is provided, and the pressure of the region of investigation may be monitored. A sealing apparatus serves to isolate the region of investigation. A parameter is estimating using the obtained measurement. The parameter estimated may include the inter-granular porosity, intra-kerogen porosity, kerogen maturity, free gas volume, and/or adsorbed gas volume. A baseline measurement may be made prior to injecting the NMR-active fluid, and the region of investigation may be evacuated before injecting the NMR-active fluid. The obtained T2 distribution can be resolved and each peak attributed to different constituent sources of the signal. The system can be conveyed into a wellbore using a drillstring, a wireline, a slickline, or a coil tubing.

First claim

What is claimed is:

1 . A system, comprising:
a nuclear magnetic resonance (NMR) measurement device; a mechanical unit containing or in fluid communication with an NMR-active injectable fluid and capable of injecting the injectable fluid into a region of investigation; and a processor capable of estimating a parameter using data obtained by the NMR measurement device regarding the region of investigation having the injectable fluid injected therein.

2 . The system of claim 1 , wherein the parameter estimated is selected from the group consisting of: inter-granular porosity, intra-kerogen porosity, kerogen maturity, free gas volume, and adsorbed gas volume.

3 . The system of claim 1 , wherein the system further comprises a sealing apparatus.

4 . The system of claim 1 , wherein the NMR-active injectable fluid is methane.

5 . The system of claim 1 , wherein the system can be conveyed into a wellbore using a logging-while-drilling drillstring, a wireline, a slickline, or a coil tubing.

6 . The system of claim 1 , wherein the region of investigation is within a volume selected from the group consisting of: a core sample, a drill cutting, a collection of drill cuttings, and a portion of a subsurface formation.

7 . The system of claim 1 , further comprising a non-metallic pressure vessel that contains a volume that includes the region of investigation.

8 . A method, comprising:
isolating a volume that includes a region of investigation; injecting an NMR-active injectable fluid into the region of investigation; performing an NMR measurement on the region of investigation containing the injected NMR-active fluid; and estimating a parameter using the obtained measurement.

9 . The method of claim 8 , further comprising:
evacuating at least a portion of any existing fluid between an NMR measurement device and the region of investigation prior to injecting the injectable fluid.

10 . The method of claim 8 , further comprising:
making a baseline NMR measurement on the region of investigation before injecting the injectable fluid.

11 . The method of claim 8 , wherein the isolating the volume comprises engaging a sealing apparatus.

12 . The method of claim 8 , wherein the NMR-active fluid is methane.

13 . The method of claim 8 , further comprising:
conveying an NMR measurement device into a wellbore proximate the region of investigation using a logging-while-drilling drillstring, a wireline, a slickline, or a coil tubing.

14 . The method of claim 8 , further comprising:
monitoring the pressure in the region of investigation.

15 . The method of claim 8 , wherein the parameter estimated is selected from the group consisting of: inter-granular porosity, intra-kerogen porosity, kerogen maturity, free gas volume, and adsorbed gas volume.

16 . The method of claim 8 , further comprising:
correlating kerogen maturity to intra-kerogen porosity based on the estimated parameter.

17 . The method of claim 8 , further comprising:
resolving, from the obtained measurement, a T2 distribution of gas molecules in intra-kerogen pores of the region of investigation.

18 . The method of claim 8 , further comprising:
resolving, from the obtained measurement, a T2 distribution of gas molecules in inter-granular porosity of the region of investigation.

19 . The method of claim 8 , further comprising:
maintaining a substantially constant pressure on the injectable fluid, and repeatedly performing the NMR measurement until the obtained measurement is substantially time-independent.

20 . The method of claim 8 , further comprising:
tuning an NMR measurement device to be consistent with the NMR-active injectable fluid.

Assignees

• Schlumberger Technology Corp

Inventors

• Badri Mohammed
• Taherian Reza

Classifications

• G01R33/448

  Relaxometry, i.e. quantification of relaxation times or spin density (G01R33/50 takes precedence) · CPC title

• G01V3/32

  operating with electron or nuclear magnetic resonance · CPC title

• G01N24/081 Primary

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

• G01R33/30

  Sample handling arrangements, e.g. sample cells, spinning mechanisms · CPC title