Plural frequency geological exploration system and method with phase comparison
First Claim
1. An exploration system for indicating subterranean formations on the basis of at least one plurality of similarly-polarized, low-frequency radiated commensurate signals of respectively different frequencies radiated from a single transmitting station, comprising:
- receiver means for sensing said radiated signals of different frequencies and having a frequency of less than 450 kilohertz, as sensed signals, at a location above a formation of interest;
means for processing said sensed signals of different frequencies as sensed by said receiver means to provide a plurality of electrically phase-comparable signals; and
means for electrically phase comparing said phase-comparable signals to provide at least one manifestation of phase difference as in indication of the medium through which said commensurate signals are transmitted and accordingly said formation of interest.
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Abstract
A system is disclosed for investigating subterranean formations by analyzing the propagation of low-frequency radio transmissions. Commensurate signals of different frequencies are received from a transmitting station and are processed into a phase-comparable form. The phase-comparable signals are then compared in phase to provide a representative signal indicative of a subterranean formation. A system utilizing at least three transmitted signals is disclosed to provide specific information related to the depth of formations. A system utilizing signals from a plurality of transmitting stations is disclosed to afford improved formation illumination. Also, a mobile form of the system is disclosed which incorporates a position-information system for combined use.
43 Citations
10 Claims
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1. An exploration system for indicating subterranean formations on the basis of at least one plurality of similarly-polarized, low-frequency radiated commensurate signals of respectively different frequencies radiated from a single transmitting station, comprising:
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receiver means for sensing said radiated signals of different frequencies and having a frequency of less than 450 kilohertz, as sensed signals, at a location above a formation of interest; means for processing said sensed signals of different frequencies as sensed by said receiver means to provide a plurality of electrically phase-comparable signals; and means for electrically phase comparing said phase-comparable signals to provide at least one manifestation of phase difference as in indication of the medium through which said commensurate signals are transmitted and accordingly said formation of interest. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of geophysically exploring a formation of interest, comprising the steps of:
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simultaneously transmitting from at least one radio transmitter located at a single transmitting station, a plurality of commensurate, similarly-polarized, phase-locked radiated signals each having a different frequency under 450 kilohertz; sensing said plurality of said phase-locked radiated signals of different frequencies at a plurality of locations above said formation of interest and removed from said radio transmitter to provide a plurality of sensed signals; phase comparing said plurality of sensed signals at each location to provide at least one phase representative signal for each location to indicate the medium through which said sensed signals are transmitted; and manifesting said phase representative signals as an indication of said formation of interest. - View Dependent Claims (10)
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Specification