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Measurement of in-phase and out-of-phase components of low frequency A.C. magnetic fields within cased boreholes to measure geophysical properties of geological formations
Measurement of in-phase and out-of-phase components of low frequency A.C. magnetic fields within cased boreholes to measure geophysical properties of geological formations
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机译:测量套管井内低频交流磁场的同相和异相分量,以测量地质构造的地球物理特性
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摘要
This invention relates to the measurement of the longitudinal components of low frequency A.C. magnetic fields from within cased boreholes which are used to measure geophysical properties of geological formations. The applied A.C. magnetic fields are generated by passing low frequency A.C. current through insulated wires or by conducting low frequency A.C. current through geological formations, either of which are examples of conducting A.C. currents through different "circuit pathways". The currents generating the applied A.C. magnetic fields are in the frequency range between 0.001 Hz and 20 Hz. The measured longitudinal components of the resulting total A.C. magnetic fields within the cased boreholes are responsive to various geophysical parameters which include the resistivities of the portions of the geological formations subject to said applied A.C. magnetic fields. Measurements of the in-phase parts and the out-of-phase parts of the longitudinal field components are defined in relation to the phases of the A.C. currents conducted through the "circuit pathways".
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