Schlumberger Technology Corporation

Richard Hunter

Liang Sun

Jiuping Chen

Luis Eduardo DePavia

David Conn

Robert W Tennent

Pavel Annenkov

Andrew G Brooks

Gaelle Jannin

Arnaud Jarrot

Michael W Schwartz

Melisa Lourdes Ramirez Tovar

Sam Soundar

Wei Zhou

Communication between the surface and a downhole location, such as a bottomhole assembly and/or an RSS is performed by electromagnetic downlink. Electromagnetic signals are transmitted from the surface through the formation at a frequency of 8 Hz or greater. Electromagnetic signals are transmitted and received while drilling or during drilling activities. In this manner, information and instructions may be transmitted to the BHA while drilling.

Electromagnetic downlink while drilling

A method includes receiving a signal having a telemetry portion and a noise portion. The method may also include identifying one or more harmonic frequencies in the signal. The method may also include determining whether the one or more harmonic frequencies are in a predetermined frequency band. The method may also include determining whether a signal-to-noise ratio (SNR) of the signal is below a predetermined SNR threshold. The method may also include generating one or more notifications in response to the determination whether the one or more harmonic frequencies are in the predetermined frequency band and the determination whether the SNR is below the predetermined SNR threshold.

Pump harmonic noise advisor

A method for steering a downhole tool includes receiving an electromagnetic (EM) signal from the downhole tool. The downhole tool is in a wellbore in a formation. The EM signal comprises a gap voltage and a gap current that are measured across a gap sub in the downhole tool. The method also includes determining a gap impedance based at least partially upon the gap voltage and the gap current. The method also includes determining a first formation resistivity at a first location in the wellbore based at least partially upon the gap impedance. The method also includes steering the downhole tool based at least partially upon the first formation resistivity.

Geo-steering using electromagnetic gap impedance data

A method for placement of electrodes includes determining spatial distribution of a signal caused by generating an electromagnetic field in an instrument disposed in drill string used to drill a wellbore. The electromagnetic field comprises encoded measurements from at least one sensor associated with the instrument. Voltages induced by noise are measured across at least one pair of spaced apart electrodes placed at a plurality of positions spaced apart from a surface location of the wellbore. A spatial distribution of noise is estimated using the measured voltages. Positions for placement of at least two electrodes are selected using the spatial distribution of signal and the spatial distribution of noise.

Method for placement of surface electrodes for electromagnetic telemetry

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Houston, TX, United States of America

Richard Hunter