Multi-dimensional dielectric logging

Patent metadata

Field	Value
Publication number	US-11048013-B2
Application number	US-201716348886-A
Country	US
Kind code	B2
Filing date	Jan 5, 2017
Priority date	Jan 5, 2017
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

A conductivity model is used for a logging tool and surrounding borehole and formation. The conductivity model is separable into a background conductivity model and an anomalous conductivity model for at least one of the formation and the tool. With the conductivity model, background electromagnetic fields and Green's functions corresponding to electromagnetic field signals at one or more receivers are computed for inversion of measured electromagnetic signals to determine adjustable parameters associated with anomalous conductivity. From the inversion, dielectric and other electromagnetic properties of the formation and borehole are determined.

First claim

What is claimed is:

1. A method comprising:
generating a complex conductivity model, wherein the complex conductivity model is separable into a homogeneous background conductivity model and an inhomogeneous anomalous conductivity model;
determining background electromagnetic fields and body-to-receiver Green's functions associated with each of two or more receivers of a dielectric logging tool based on the homogeneous background conductivity model; and
determining a scattering tensor, wherein the scattering tensor relates the background electromagnetic fields to at least of a conductivity contrast and an anomalous electric field, wherein the conductivity contrast is a difference in conductivity between homogeneous background conductivity for the homogeneous background conductivity model and a second homogeneous background conductivity model; and
determining one or more properties of a formation based, at least in part, on received electromagnetic response signals, the background electromagnetic fields, the body-to-receiver Green's functions, the scattering tensor, and the inhomogeneous anomalous conductivity model,
wherein the received electromagnetic response signals comprise response signals measured at the two or more receivers of the dielectric logging tool in response to electromagnetic signals emitted towards the formation.

2. The method of claim 1 , wherein the complex conductivity model comprises a complex conductivity model of the dielectric logging tool that describes at least one of a three-dimensional shape of the dielectric logging tool, material properties of the dielectric logging tool, dielectric fill of the one or more receivers, and dielectric fill of a transmitter antenna of the dielectric logging tool.

3. The method of claim 1 , wherein determining the background electromagnetic fields and the body-to-receiver Green's functions comprises computing the background electric fields and the body-to-receiver Green's functions based on the homogeneous background conductivity model.

4. The method of claim 1 , wherein determining the background electromagnetic fields and the body-to-receiver Green's functions comprises selecting precomputed background electric fields and precomputed body-to-receiver Green's functions.

5. The method of claim 1 , wherein the one or more properties of the formation comprise at least one of electrical properties, geophysical properties, fluid properties, and rock properties.

6. The method of claim 1 , wherein the inhomogeneous anomalous conductivity model of the formation is radially symmetric about a longitudinal axis of a borehole.

7. The method of claim 1 , wherein determining one or more properties of the formation comprises determining at least one sensitivity with respect to an inhomogeneous anomalous conductivity.

8. A system comprising:
a dielectric logging tool comprising a transmitter and two or more receivers; and
a computational facility comprising,
a processor, and
processor-executable instructions, the processor-executable instructions executable by the processor to cause the system to,
obtain a complex conductivity model corresponding to at least one of a formation and the dielectric logging tool, wherein the complex conductivity model is separable into a homogeneous background conductivity model and an inhomogeneous anomalous conductivity model,
determine background electromagnetic fields and body-to-receiver Green's functions for each of the two or more receivers based on the homogeneous background conductivity model,
determine a scattering tensor, wherein the scattering tensor relates the background electromagnetic fields to at least one of a conductivity contrast and an anomalous electric field, wherein the conductivity contrast is a difference between homogeneous background conductivity for the homogeneous background conductivity model and a second homogeneous background conductivity model; and
determine one or more properties of the formation based, at least in part, on signals received by the two or more receivers, the background electromagnetic fields, the body-to-receiver Green's functions, the scattering tensor, and the inhomogeneous anomalous conductivity model.

9. The system of claim 8 , wherein the processor-executable instructions to determine the background electromagnetic fields and the body-to-receiver Green's functions comprise processor-executable instructions to determine the background electromagnetic fields and the body-to-receiver Green's functions by computation.

10. The system of claim 8 , wherein the processor-executable instructions to determine the background electromagnetic fields and the body-to-receiver Green's functions comprise processor-executable instructions to retrieve precomputed background electromagnetic fields and precomputed body-to-receiver Green's functions.

11. A computer-readable medium storing instructions for execution by one or more processors of a computer, the instructions, when executed, causing the computer to:
obtain electromagnetic signals measured with two or more receivers of a dielectric logging tool, wherein the obtained electromagnetic signals comprise signals measured in response to emission of an electromagnetic signal towards a formation;
determine background electromagnetic fields and body-to-receiver Green's functions for each of the two or more receivers, wherein the background electromagnetic fields and the body-to-receiver Green's functions are based on a homogeneous background conductivity model;
determine a scattering tensor, wherein the scattering tensor relates the background electromagnetic fields to at least one of a conductivity contrast and an anomalous electric field; and
determine one or more properties of the formation based at least in part on the obtained electromagnetic signals, the determined background electromagnetic fields, the determined body-to-receiver Green's functions, the scattering tensor, and an inhomogeneous anomalous conductivity model.

12. The computer-readable medium of claim 11 , wherein the instructions to determine the background electromagnetic fields and the body-to-receiver Green's functions comprise instructions to cause the computer to calculate the background electromagnetic fields and the body-to-receiver Green's functions.

13. The computer-readable medium of claim 11 , wherein the one or more properties of the formation comprise at least one of electrical properties, geophysical properties, fluid properties and rock properties.

14. The computer-readable medium of claim 11 , wherein the instructions to determine the one or more properties of the formation further comprise instructions to determine at least one sensitivity with respect to an inhomogeneous anomalous conductivity.

15. The method of claim 1 , wherein determining the one or more properties of the formation comprises inverting the received electromagnetic response signals based, at least in part, on the background electromagnetic fields, the body-to-receiver Green's functions, and the inhomogeneous anomalous conductivity model.

16. The method of claim 1 , wherein determining the one or more properties of the formation comprises determining an inhomogeneous anomalous conductivity.

17. The system of claim 8 , wherein the processor-executable instructions to determine the one or more properties of the formation comprise processor-executable instructions to invert the signals received by the two or more receivers based, at least in part, on the background electromagnetic fields, the body-to-receiver Green's functions, and the inhomogeneous anomalous c

Assignees

• Halliburton Energy Services Inc

Inventors

• Wilson Glenn A
• Ewe Wei-Bin

Classifications

• G01V3/26

  operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device (with electromagnetic waves G01V3/30) · CPC title

• G01V3/30 Primary

  operating with electromagnetic waves · CPC title

• G01V3/38

  Processing data, e.g. for analysis, for interpretation, for correction · CPC title