CPC E21B 47/003 (2020.05) [E21B 47/13 (2020.05); E21B 49/08 (2013.01); G01V 3/34 (2013.01); G01V 3/38 (2013.01)] | 20 Claims |
1. A method for characterizing a geological formation, comprising:
using a downhole logging device to perform multifrequency electromagnetic measurements of the geological formation;
determining a plurality of complex permittivities of the geological formation at a plurality of frequencies from the multifrequency electromagnetic measurements, wherein the plurality of frequencies comprise two frequencies f2 and f1;
determining a plurality of complex permittivities of water in the geological formation at the plurality of frequencies from the multifrequency electromagnetic measurements; and
determining a value of at least one formation parameter from the plurality of complex permittivities of the geological formation and the plurality of complex permittivities of water in the geological formation, wherein the at least one formation parameter is selected from the group consisting of water-filled porosity of the geological formation, water salinity, water saturation, tortuosity of water-filled pore space, and combinations thereof, and wherein determining the value of the at least one formation parameter from the plurality of the complex permittivities of the geological formation and the plurality of complex permittivities of water in the geological formation comprises selectively determining a value of the water-filled porosity based on evaluation of a quality index derived from a real part and an imaginary part of an expression involving the plurality of complex permittivities of the geological formation and the plurality of complex permittivities of water in the geological formation at the two frequencies f2 and f1.
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