METHOD OF REAL TIME SUBSURFACE IMAGING USING ELECTROMAGNETIC DATA ACQUIRED FROM MOVING PLATFORMS

• US 20130018585A1
• Filed: 06/04/2012
• Published: 01/17/2013
• Est. Priority Date: 07/15/2011
• Status: Active Grant

• Current Assignee: TechnoImaging, LLC
• Original Assignee: TechnoImaging, LLC
• Inventors: Zhdanov, Michael S., Wilson, Glenn A., Cox, Leif H.
• Granted Patent: US 9,322,910 B2
• Time in Patent Office: Days
• US Class Current: 702/2
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01V 3/083 Controlled source electromagnetic [CSEM] surveying
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat
• CPC Class Codes: G01V 3/16 specially adapted for use from aircraft G01V3/165 - G01V3/175 take precedence

Abstract

A method for the real time volume imaging of geological structures and/or man-made objects having electrical conductivity is described, using electromagnetic (EM) sources and/or EM sensors mounted from at least one moving platform. The EM sources may include natural EM sources and/or man-made inductive sources and/or man-made galvanic sources. The EM sensors may measure at least one component of the EM field at the at least one sensor position. The EM fields measured for each combination of EM source and EM sensor may be volume imaged in real time using a moving sensitivity domain that captures the finite spatial sensitivity of each combination of EM sources and EM sensors. At least one desired property, such as conductivity, dielectric permittivity and/or induced polarization parameters, may be derived from the volume image, providing a reconstruction or classification of the physical properties of the geological structures and/or man-made objects.

Claims

1. A method for real time volume imaging of electrical conductivity of an examined medium from electromagnetic (EM) data measured from at least one moving platform, the method comprising:

a. placing at least one EM source and/or EM sensor in at least one position on at least one moving platform from the start of a survey up to a given time moment t;

b. measuring at least one component of electric and/or magnetic field data with at least one EM sensor in at least one receiving position along at least one survey line by the at least one moving platform from the start of a survey up to a given time moment t;

c. calculating a temporal sensitivity for the EM data measured at the at least one receiver operating from the start of the survey up to the given time moment t using a perturbation of the electrical conductivity within the moving sensitivity domain of the EM source and EM sensor sensitivities of the at least one moving platform;

d. constructing a temporal 3D volume image of the electrical conductivity for the given time moment t by applying an iterative linearized inversion and/or migration with line search and/or preconditioning to the temporal EM data measured by the at least one moving platform from the start of the survey up to the given time moment t.

2. The method of claim 1, wherein the electrical conductivity comprises one of conductivity, dielectric permittivity, and/or induced polarization parameters, representing the physical properties of the examined medium containing natural structures (e.g. mineral deposit or hydrocarbon reservoir) or man-made objects;

3. The method of claim 1, wherein the at least one EM sensor comprises a plurality of EM sensors arranged in an array.

4. The method of claim 3, wherein the plurality of EM sensors include inductive and/or galvanic and/or capacitive sensors.

5. The method of claim 1, wherein the EM sources may be controlled EM sources including man-made inductive sources and/or man-made galvanic sources located at least one fixed position with respect to the at least one moving platform.

6. The method of claim 1, wherein the EM sources may be controlled EM sources including man-made inductive sources and/or man-made galvanic sources located on the at least one moving platform.

7. The method of claim 1, wherein the EM sources may be natural EM sources.

8. The method of claim 1, wherein the forward modeling, inversion and/or migration of the EM data includes an algorithm based on a numerical solution of Maxwell'"'"'s equations in either the frequency-domain or the time-domain including but not limited to semi-analytical, finite difference, finite element, boundary element, integral equation and/or hybrid numerical methods.

9. The method of claim 1, wherein the forward modeling comprises of algorithms based on linear approximations.

10. The method of claim 1, wherein imaging is based on the inversion and/or migration comprised of

a) an algorithm based on an iterative linearized method and/or line search and/or preconditioning technique;

b) temporal sensitivities and/or their actions calculated implicitly and/or explicitly using adjoint operators;

c) temporal sensitivities and/or their actions calculated implicitly and/or explicitly using linear approximations;

d) an algorithm based on regularization including smooth and/or focusing stabilizers and/or combinations thereof;

e) an algorithm based on a temporal moving sensitivity domain of the EM source and EM sensor sensitivities;

f) an algorithm based using the initial 3D electrical conductivity model at the time moment t_n may be constructed from in real time from the 3D electrical conductivity model at the time moment t_n-1.

11. The method of claim 1, wherein at least one moving platform is a vessel.

12. The method of claim 1, wherein at least one moving platform is a wireline device.

13. The method of claim 1, wherein at least one moving platform is a bottom hole assembly.

14. The method of claim 1, wherein at least one moving platform is an unattended aerial system.

15. The method of claim 1, wherein at least one moving platform is a helicopter.

16. The method of claim 1, wherein at least one moving platform is a fixed wing aircraft.

17. The method of claim 1, wherein at least one moving platform is an airship.

18. The method of claim 1, wherein at least one moving platform is a vehicle.

19. The method of claim 1, wherein the examined medium contains a geological structure.

20. The method of claim 1, wherein volume images for variations in the subsurface electrical conductivity may be obtained from time-lapsed surveys.

21. A physical non-transitory computer readable medium having stored thereon computer executable instructions that when executed by a processor cause a computing system to perform a method for rapid real time imaging of electrical conductivity from moving platforms using at least one EM source and/or EM sensor placed in at least one position on at least one moving platform from the start of a survey up to a given time moment t, the method comprising:

a. measuring at least one component of electric and/or magnetic field data with at least one EM sensor in at least one receiving position along at least one survey line by the at least one moving platform from the start of a survey up to a given time moment t;

b. calculating a temporal sensitivity for the EM data measured at the at least one receiver operating from the start of the survey up to the given time moment t using a perturbation of the electrical conductivity within the moving sensitivity domain of the EM source and EM sensor sensitivities of the at least one moving platform;

c. constructing a temporal 3D volume image of the electrical conductivity for the given time moment t by applying an iterative linearized inversion and/or migration with line search and/or preconditioning to the temporal EM data measured by the at least one moving platform from the start of the survey up to the given time moment t.

22. A system for rapid real time imaging of electrical conductivity from moving platforms comprising:

a moving platform;

at least one EM source and/or EM sensor configured to generate and/or measure one component of electric and/or magnetic field data; and

a computing system comprising;

a processor;

one or more physical non-transitory computer readable medium having computer executable instructions stored thereon that when executed by the processor, cause the computing system to perform the following;

a. measure at least one component of electric and/or magnetic field data with at least one EM sensor in at least one receiving position along at least one survey line by the at least one moving platform from the start of a survey up to a given time moment t;

b. calculate a temporal sensitivity for the EM data measured at the at least one receiver operating from the start of the survey up to the given time moment t using a perturbation of the electrical conductivity within the moving sensitivity domain of the EM source and EM sensor sensitivities of the at least one moving platform;

c. construct a temporal 3D volume image of the electrical conductivity for the given time moment t by applying an iterative linearized inversion and/or migration with line search and/or preconditioning to the temporal EM data measured by the at least one moving platform from the start of the survey up to the given time moment t.