INDUCTIVE DOWNHOLE SENSOR WITH CENTER TAP FOR COMMON MODE REJECTION

Systems, methods, and devices for evaluation of an earth formation intersected by a borehole using a logging tool. Methods include generating an excitation in the formation with an electromagnetic (EM) signal from a transmitter assembly at at least one frequency; making EM measurements using an EM t...

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Hauptverfasser: ZLOTNIK, Alexander, KIRCHMEIER, Eduard
Format: Patent
Sprache:eng ; fre ; ger
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Beschreibung
Zusammenfassung:Systems, methods, and devices for evaluation of an earth formation intersected by a borehole using a logging tool. Methods include generating an excitation in the formation with an electromagnetic (EM) signal from a transmitter assembly at at least one frequency; making EM measurements using an EM tool on a tool string in the borehole by receiving a signal at at least one receiver assembly responsive to the excitation; wherein the at least one receiver assembly includes an induction antenna comprising a first winding and a second winding that share a common center tap, and wherein the average potential on the induction antenna is substantially the same as a ground potential. The receiver assembly or transmitter assembly may comprise a receiver or transmitter electrically connected to the induction antenna by a balun transformer, and a capacitive shield encompassing the induction antenna, the capacitive shield comprising a meander shaped isolation gap.