Granted Patent B2

US 12,565,823 · App. 17/653,802 · Granted Mar 3, 2026

Inventors: Jose Oliverio Alvarez (Houston, TX); David Joseph Jacobi (Houston, TX)

Assignee: SAUDI ARABIAN OIL COMPANY

E21B36/04G01N22/00E21B2200/22

Abstract

Claims (56)

1 . A system for determining shale rock maturity, the system comprising:

a dual mode microwave cavity configured to receive a shale sample obtained from a geological formation;

a heating system configured to heat the shale sample to a range of different temperatures using microwave emissions of a first frequency;

a measuring system configured to measure a complex permittivity of the shale sample using a microwave signal of a second frequency; and

a processor configured to:

obtain an imaginary part of the complex permittivity; and

determine the shale rock maturity based on a relaxation in the imaginary part,

comprising:

identifying a maximum S1 in a first temperature range and a maximum S 2 in a second temperature range higher than the first temperature range;

computing a ratio S1/(S1+S2) to obtain a productivity index; and

evaluating the productivity index to obtain the shale rock maturity,

wherein the shale rock maturity is used to determine a viability of the geological formation,

informing operation of a drilling system for production of hydrocarbons from the geological formation.

2 . The system of claim 1 , further comprising a sample vial insertable into the dual mode microwave cavity,

wherein the sample vial is configured to hold the shale sample.

3 . The system of claim 1 , further comprising a thermometer, configured to monitor the heating of the shale sample.

4 . The system of claim 1 , wherein the dual mode microwave cavity is cylindrical.

5 . The system of claim 1 , wherein the microwave emissions of the heating system establish a resonant TE 111 mode inside the dual mode microwave cavity.

6 . The system of claim 1 , wherein the microwave signal of the measuring system establishes a resonant TM 010 mode inside the dual mode microwave cavity.

7 . The system of claim 1 ,

wherein the measuring system comprises a cross-coupling filter configured to attenuate at the first frequency.

8 . A method for determining shale rock maturity, the method comprising:

measuring a complex permittivity of a shale sample obtained from aa geological formation as a function of temperature;

obtaining an imaginary part of the complex permittivity; and

determining the shale rock maturity based on a relaxation in the imaginary part, comprising:

identifying a maximum S1 in a first temperature range and a maximum S2 in a second temperature range higher than the first temperature range;

computing a ratio S1/(S1+S2) to obtain a productivity index; and

evaluating the productivity index to obtain the shale rock maturity,

wherein the shale rock maturity is used to determine a viability of the geological formation,

informing operation of a drilling system for production of hydrocarbons from the geological formation.

9 . The method of claim 8 , wherein measuring the complex permittivity of the shale sample comprises:

obtaining the shale sample;

heating the shale sample; and

recording the complex permittivity during the heating.

10 . The method of claim 9 , wherein obtaining the shale sample comprises:

extracting the shale sample from a core plug obtained from a well.

11 . The method of claim 9 , wherein heating the shale sample comprises:

generating microwave emissions; and

exposing the shale sample to the microwave emissions.

12 . The method of claim 9 , wherein heating shale sample comprises:

heating the shale sample according to a temperature profile specifying a continuously increasing temperature.

13 . The method of claim 8 , wherein measuring the complex permittivity comprises:

measuring the complex permittivity using a microwave signal.

14 . The method of claim 8 , wherein determining the shale rock maturity based on the relaxation in the imaginary part further comprises:

processing the imaginary part by a machine learning model to obtain the shale rock maturity.

15 . The method of claim 14 , further comprising:

training the machine learning model based on samples of known maturity.

16 . A non-transitory machine-readable medium comprising a plurality of machine-readable instructions executed by one or more processors, the plurality of machine-readable instructions causing the one or more processors to perform operations comprising:

determining a shale rock maturity of a shale sample obtained from a geological formation based on a relaxation in an imaginary part of a complex permittivity, comprising:

identifying a maximum S1 of the imaginary part in a first temperature range and a maximum S2 of the imaginary part in a second temperature range higher than the first temperature range;

computing a ratio S1/(S1+S2) to obtain a productivity index; and

evaluating the productivity index to obtain the shale rock maturity,

wherein the complex permittivity of the shale sample is a function of a temperature of the shale sample, and

wherein the shale rock maturity is used to determine a viability of the geological formation, informing operation of a drilling system for production of hydrocarbons from the geological formation.

17 . The non-transitory machine-readable medium of claim 16 , wherein determining the shale rock maturity based on the relaxation in the imaginary part further comprises:

processing the imaginary part by a machine learning model to obtain the shale rock maturity.

Assignments (3)

Continuity (1)

References Cited (20)