Magneto-seismic exploration method and system

Patent metadata

Field	Value
Publication number	US-10101495-B2
Application number	US-201715444803-A
Country	US
Kind code	B2
Filing date	Feb 28, 2017
Priority date	Mar 10, 2016
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

Systems and methods are provided for a magneto-seismic exploration of a subsurface region. An electromagnetic source may transmit time-varying electromagnetic field into the subsurface region, in the presence of a static or time-varying magnetic field, such that a component of the electric field associated with the time-varying electromagnetic field is substantially parallel to an interface between two subsurface formations in the subsurface region, wherein the electric field interacts with the static or time-varying magnetic field and creates a Lorentz force in each of the subsurface formations. One or more seismic receivers may detect a seismic signal generated by a Lorentz force change at the interface between the two subsurface formations. A computer system may be programmed to process and present the detected seismic signal.

First claim

What is claimed is:

1. A method for a magneto-seismic exploration of a subsurface region, comprising:
transmitting a time-varying electromagnetic field into a subsurface region, such that a source of the time-varying electromagnetic field is arranged to have a component of an electric field associated with the time-varying electromagnetic field be substantially parallel to an interface, at depth, between two subsurface formations in the subsurface region and be substantially parallel or substantially perpendicular to a component of a magnetic field that is substantially parallel to the interface at depth, wherein the magnetic field is a static or time-varying magnetic field, and the component of the electric field interacts with the component of the magnetic field and creates a Lorentz force in each of the subsurface formations;
detecting, with one or more seismic receivers, a magneto-seismic signal generated by the Lorentz force change at the interface between the two subsurface formations; and
using a computer system to process and present the detected magneto-seismic signal.

2. The method of claim 1 , wherein the Lorentz force change results from a difference between conductivities of the two subsurface formations.

3. The method of claim 1 , wherein the source of time-varying electromagnetic field is an electromagnetic power source.

4. The method of claim 3 , further comprising choosing a frequency content of the electromagnetic power source according to a thickness of one of the two subsurface formations.

5. The method of claim 3 , further comprising choosing a frequency content of the electromagnetic power source according to a depth of one of the two subsurface formations.

6. The method of claim 3 , further comprising choosing one or both of a frequency content and an amplitude of the electromagnetic power source to improve a signal to noise ratio of the detected magneto-seismic signal.

7. The method of claim 3 , wherein the electromagnetic power source is coupled to either a pair of railroad track electrodes, a pair of dipole electrodes, or a magnetic induction coil.

8. The method of claim 1 , wherein the magnetic field is the earth's magnetic field.

9. The method of claim 1 , wherein the magnetic field is generated by an electromagnet or a permanent magnet.

10. The method of claim 1 , wherein the time-varying electromagnetic field is transmitted from an earth's surface into the subsurface region.

11. The method of claim 1 , wherein the time-varying electromagnetic field is transmitted from a sea or sea floor into the subsurface region.

12. The method of claim 1 , wherein the time-varying electromagnetic field is transmitted from a wellbore in the subsurface region.

13. The method of claim 1 , wherein at least one of the seismic receivers is located at the earth's surface above the subsurface region.

14. The method of claim 1 , wherein at least one of the seismic receivers is located in a sea or on a sea floor above the subsurface region.

15. The method of claim 1 , wherein at least one of the seismic receivers is located inside a wellbore in the subsurface region.

16. The method of claim 1 , wherein the detected magneto-seismic signal includes one or both of a compressional wave and a shear wave.

17. The method of claim 1 , wherein the one or more seismic receivers are configured to detect compressional and shear waves.

18. The method of claim 1 , wherein the method further comprises generating, with the computer system, a conductivity map of the subsurface region.

19. The method of claim 1 , further comprising orienting electrodes of the source to generate the component of the electric field; and disposing at least one of the one or more receivers between the electrodes.

20. The method of claim 1 , further comprising disposing a source of the magnetic field in a wellbore.

21. A system for a magneto-seismic exploration of a subsurface region, comprising:
an electromagnetic power source configured to transmit a time-varying electromagnetic field into a subsurface region, in the presence of a static or time-varying magnetic field, such that the electromagnetic power source of the time-varying electromagnetic field is disposed to have a component of an electric field associated with the time-varying electromagnetic field be substantially parallel to an interface, at depth, between two subsurface formations in the subsurface region and be substantially parallel or substantially perpendicular to a component of a magnetic field that is substantially parallel to the interface at depth, wherein the magnetic field is a static or time-varying magnetic field, and the component of the electric field interacts with the component of the magnetic field and creates a Lorentz force in each of the subsurface formations;
one or more seismic receivers configured to detect a magneto-seismic signal generated by the Lorentz force change at the interface between the two subsurface formations; and
a computer system programmed to process and present the detected magneto-seismic signal.

22. The system of claim 21 , wherein a frequency range of the electromagnetic power source is chosen according to a thickness of one of the two subsurface formations.

23. The system of claim 21 , wherein a frequency range of the electromagnetic power source is chosen according to a depth of one of the two subsurface formations.

24. The system of claim 21 , wherein one or both of a frequency content and an amplitude of the electromagnetic power source are chosen to improve a signal to noise ratio of the detected magneto-seismic signal.

25. The system of claim 21 , wherein the electromagnetic power source is coupled to one of a pair of railroad track electrodes, a pair of dipole electrodes, and a magnetic induction coil.

26. The system of claim 21 , wherein the electromagnetic power source is configured to transmit the time-varying electromagnetic field from the earth's surface into the subsurface region.

27. The system of claim 21 , wherein the electromagnetic power source is configured to transmit the time-varying electromagnetic from a sea or sea floor into the subsurface region.

28. The system of claim 21 , wherein the electromagnetic power source is configured to transmit the time-varying electromagnetic field from a wellbore in the subsurface region.

29. The system of claim 21 , wherein at least one of the seismic receivers is located at the earth's surface above the subsurface region.

30. The system of claim 21 , wherein at least one of the one or more seismic receivers is located in a sea or on a sea floor above the subsurface region.

31. The system of claim 21 , wherein at least one of the one or more seismic receivers is located inside a wellbore in the subsurface region.

32. The system of claim 21 , wherein at least one of the one or more seismic receivers is configured to detect compressional and shear waves.

33. The system of claim 21 , wherein the computer system is programmed to process the detected magneto-seismic signal to generate a conductivity map of the subsurface region.

34. The system of claim 21 , wherein the transmitted time-varying electromagnetic field has significant energy content in a frequency range between 0.0001 Hz and 10,000 Hz.

Assignees

• Exxonmobil Res & Eng Co

Inventors

• Li Qiuzi
• Deckman Harry W
• Ertas Mehmet Deniz

Classifications

• G01V11/007 Primary

  using the seismo-electric effect · CPC title

• G01V2210/1429

  Subsurface, e.g. in borehole or below weathering layer or mud line · CPC title

• G01V2210/1297

  Sea bed · CPC title

• G01V2210/1425

  Land surface · CPC title

• G01V2210/1299

  Subsurface, e.g. in borehole or below weathering layer or mud line · CPC title