Electromagnetic logging between a cased borehole and surface

The present disclosure relates to systems and methods for conducting an electromagnetic borehole-to-surface survey of a formation surrounding a borehole. Such methods include deploying a dipole transmitter into the borehole to a depth of investigation, deploying an array of electromagnetic receivers...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser: ROSTHAL RICHARD A, ZHANG HONG
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:The present disclosure relates to systems and methods for conducting an electromagnetic borehole-to-surface survey of a formation surrounding a borehole. Such methods include deploying a dipole transmitter into the borehole to a depth of investigation, deploying an array of electromagnetic receivers outside of the wellbore, and measuring a response of the formation at the array of electromagnetic receivers deployed outside of the wellbore, for example at the surface. From the response of the formation a property of the formation can be determined based on the response of the formation measured at the array of electromagnetic receivers. For the scenario of a cased well, a local reference receiver may be added at a location proximate the borehole to measure the effective magnetic moment of the transmitter inside the casing, and normalize the formation response in order for a more accurate determination of a formation characteristic, such as resistivity. These receivers can also be used for other types of surveys.