Method using near and far field ULF and ELF interferometry synthetic aperture radar for subsurface imaging

摘要

This invention relates to devices and processes for geophysical prospecting, subsurface fluid monitoring and, more particular, to the use of interferometric techniques using Control Source Electromagnetic (“CSEM”) and Magnetoturelic (“MT”) signals to create images of sub-surface structures and fluids.

主权项

1. A method of subsurface monitoring via interferometric techniques using control source electromagnetic signals, the method comprising the following steps:
a. positioning at least one transmitter on a surface, said at least one transmitter positioned at an angle less than a critical angle with respect to a normal of a target structure, said critical angle dependent on each transmission frequency, said at least one transmitter additionally positioned such that transmissions are directed towards said target structure, said target structure beneath said surface, wherein said at least one transmitter are capable of transmitting one or more phase coherent chirps created using a plurality of said transmission frequencies; b. positioning at least two receivers on said surface, said at least two receivers positioned such that said transmissions from said at least one transmitter are received by at least one of said at least two receivers, wherein said at least two receivers are capable of detecting small phase shifts and amplitude changes from chirps through phase coherence; c. wherein said at least one transmitter and said at least two receivers are phase and/or time coherent with a low drift synchronizing clock; d. recording data received by said at least two receivers in response to said chirps; e. repeating steps a. through d. for a plurality of said transmission frequencies, said angles, and/or the positions on said surface; and f. creating at least one interferometric images of said target structure from said data using data framing, wherein said data framing creates data samples which are phase coherent and coherent with said low drift synchronizing clock.