METHOD FOR DETECTING FORMATION RESISTIVITY OUTSIDE OF METAL CASING USING TIME-DOMAIN ELECTROMAGNETIC PULSE IN WELL

A method for detecting formation resistivity outside of metal casing using time-domain electromagnetic pulse in a borehole, the method including steps of a) providing a borehole large power pulse transmitting source, recording an induced electromotive force , and full time digital recording a transm...

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Hauptverfasser: LUO MINGZHANG, XIANG KUI, HU WENBAO, YAN LIANGJUN, TANG XINGONG, CHEN QINGLI, LIU DIREN, XIE XINGBING, SU ZHULIU, XU ZHENPING, MAO YURONG, WANG JUNMIN
Format: Patent
Sprache:eng
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Zusammenfassung:A method for detecting formation resistivity outside of metal casing using time-domain electromagnetic pulse in a borehole, the method including steps of a) providing a borehole large power pulse transmitting source, recording an induced electromotive force , and full time digital recording a transmitted waveform and a received signal; b) conducting transmission-reception and superimposing received signals to improve signal to noise ratio; c) calculating corresponding casing response according to known casing parameters and recorded current waveform of the transmitting source to obtain a relative induced electromotive force f; d) correcting relative induced electromotive force value; e) carrying out one-dimensional inversion and converting the observation signal into radial variation information of the formation resistivity; f) obtaining a two-dimensional image of the longitudinal and radial resistivity distribution of outer cased formation resistivity for measured well sections; and g) determining residual oil distribution in a reservoir from outer cased reservoir resistivity distribution.