Method of real time subsurface imaging using electromagnetic data acquired from moving platforms
First Claim
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 physical EM source and/or physical EM sensor in at least one position on at least one moving platform and moving the moving platform from the start of a survey up to a given time moment t;
b. measuring while the moving platform is moving at least one component of electric and/or magnetic field data with the at least one physical EM sensor in at least one receiving position on the moving platform along at least one survey line by the at least one moving platform from the start of the survey up to the given time moment t;
c. computing predicted at least one component of EM data from the start of the survey up to the given time moment t by use of an initial 3D electrical conductivity model that is based on known information regarding the examined medium;
d. calculating a temporal sensitivity for the EM data measured at the at least one physical EM sensor 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 physical EM source and physical EM sensor sensitivities of the at least one moving platform;
e. comparing the computed predicted EM data with the EM data measured at the at least one physical EM sensor to determine an error value between the predicted EM data and the measured EM data;
f. constructing a temporal 3D volume image of the electrical conductivity for the given time moment t when the error value is less than a predetermined threshold value 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; and
g. outputting the temporal 3D image,wherein when the error value is greater than the predetermined threshold value;
the initial 3D electrical conductivity model is updated and an updated predicted at least one component of EM data is calculated;
the updated predicted at least one component of EM data is compared with the EM data measured at the at least one physical EM sensor to determine an updated error value between the predicted EM data and the measured EM data; and
the temporal 3D volume image is constructed when the updated error value is less than the predetermined threshold value.
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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.
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Citations
22 Claims
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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:
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a. placing at least one physical EM source and/or physical EM sensor in at least one position on at least one moving platform and moving the moving platform from the start of a survey up to a given time moment t; b. measuring while the moving platform is moving at least one component of electric and/or magnetic field data with the at least one physical EM sensor in at least one receiving position on the moving platform along at least one survey line by the at least one moving platform from the start of the survey up to the given time moment t; c. computing predicted at least one component of EM data from the start of the survey up to the given time moment t by use of an initial 3D electrical conductivity model that is based on known information regarding the examined medium; d. calculating a temporal sensitivity for the EM data measured at the at least one physical EM sensor 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 physical EM source and physical EM sensor sensitivities of the at least one moving platform; e. comparing the computed predicted EM data with the EM data measured at the at least one physical EM sensor to determine an error value between the predicted EM data and the measured EM data; f. constructing a temporal 3D volume image of the electrical conductivity for the given time moment t when the error value is less than a predetermined threshold value 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; and g. outputting the temporal 3D image, wherein when the error value is greater than the predetermined threshold value; the initial 3D electrical conductivity model is updated and an updated predicted at least one component of EM data is calculated; the updated predicted at least one component of EM data is compared with the EM data measured at the at least one physical EM sensor to determine an updated error value between the predicted EM data and the measured EM data; and the temporal 3D volume image is constructed when the updated error value is less than the predetermined threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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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 physical EM source and/or physical EM sensor placed in at least one position on at least one moving platform, where the moving platform is moved from the start of a survey up to a given time moment t, the method comprising:
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a. measuring while the moving platform is moving at least one component of electric and/or magnetic field data with the at least one physical EM sensor in at least one receiving position on the moving platform along at least one survey line by the at least one moving platform from the start of the survey up to the given time moment t; b. computing predicted at least one component of EM data from the start of the survey up to the given time moment t by use of an initial 3D electrical conductivity model that is based on known information regarding an examined medium; c. calculating a temporal sensitivity for the EM data measured at the at least one physical EM sensor 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 physical EM source and physical EM sensor sensitivities of the at least one moving platform; d. comparing the computed predicted EM data with the EM data measured at the at least one physical EM sensor to determine an error value between the predicted EM data and the measured EM data; e. constructing a temporal 3D volume image of the electrical conductivity for the given time moment t when the error value is less than a predetermined threshold value 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; and f. outputting the temporal 3D image, wherein when the error value is greater than the predetermined threshold value; the initial 3D electrical conductivity model is updated and an updated predicted at least one component of EM data is calculated; the updated predicted at least one component of EM data is compared with the EM data measured at the at least one physical EM sensor to determine an updated error value between the predicted EM data and the measured EM data; and the temporal 3D volume image is constructed when the updated error value is less than the predetermined threshold value.
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22. A system for rapid real time imaging of electrical conductivity from moving platforms comprising:
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a moving platform; at least one physical EM source and/or physical EM sensor configured to generate and/or measure one component of electric and/or magnetic field data, wherein the at least one physical EM source and/or physical EM sensor are positioned on the moving platform; 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 while the moving platform is moving at least one component of electric and/or magnetic field data with the at least one physical EM sensor in at least one receiving position on the moving platform along at least one survey line by the at least one moving platform from the start of the survey up to the given time moment t; b. compute predicted at least one component of EM data from the start of the survey up to the given time moment t by use of an initial 3D electrical conductivity model that is based on known information regarding the examined medium; c. calculate a temporal sensitivity for the EM data measured at the at least one physical EM sensor 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 physical EM source and physical EM sensor sensitivities of the at least one moving platform; d. compare the computed predicted EM data with the EM data measured at the at least one physical EM sensor to determine an error value between the predicted EM data and the measured EM data; e. constructing a temporal 3D volume image of the electrical conductivity for the given time moment t when the error value is less than a predetermined threshold value 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; and f. outputting the temporal 3D image, wherein when the error value is greater than the predetermined threshold value; the initial 3D electrical conductivity model is updated and an updated predicted at least one component of EM data is calculated; the updated predicted at least one component of EM data is compared with the EM data measured at the at least one physical EM sensor to determine an updated error value between the predicted EM data and the measured EM data; and the temporal 3D volume image is constructed when the updated error value is less than the predetermined threshold value.
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Specification