TY - CONF
T1 - Directional induction logging methods
AU - Sato, Motoyuki
AU - Fuziwara, Jun
AU - Miyairi, Makoto
AU - Kashihara, Koji
AU - Niitsuma, Hiroaki
N1 - Funding Information:
Hiroaki Niitsuma received a B.E.(1970), an M.E.(1972) and a Ph.D.(1975) in electrical communication engineering from Tohoku University, where he is currently professor in the Dept. of Resources Engineering. He is a member of the Research Group of Geothermal Energy Extraction Engineering (GEEE) at TU and engagedi n a research project (HWR-project) supportedb y the governmento f Japan. He is a chairman of subsurfacei nstrumentation division of the Mining and Material Processing Institute of Japan (MMIJ).
Publisher Copyright:
© 1994 Society of Petrophysicists and Well-Log Analysts. All Rights Reserved.
PY - 1994
Y1 - 1994
N2 - A new induction logging tool which has two coils whose axis is tilted from a borehole axis, resulting unsymmetrical configuration around a borehole is proposed. This configuration increases a sensitivity at one direction. This unsymmetrical sensor is mechanically rotated around a borehole axis and measures the electrical resistivity distribution. Comparing to other directional logging tools investigated before, the presented tool has a simple structure, but has a good directivity. Fundamental characteristics of this tool was theoretically investigated. The Born approximation, i.e., a conventional geometrical factor which has been widely used for the analysis of a induction logging system was generalized to tilt coil arrangements and was applied. The effect of tilt angle, coil separation and operation frequency were studied. A prototype model of the presented tool was fabricated and tested in a formation model. This model has inclined boundaries of formations having different conductivities. The measurement shows that this tool has a directional sensitivity as is expected from the theory. It was found from the theoretical analysis and experimental measurements that this system can measure the true resistivity of each formation as the conventional induction logging systems, and additionally it can make deep azimuthal resistivity measurement.
AB - A new induction logging tool which has two coils whose axis is tilted from a borehole axis, resulting unsymmetrical configuration around a borehole is proposed. This configuration increases a sensitivity at one direction. This unsymmetrical sensor is mechanically rotated around a borehole axis and measures the electrical resistivity distribution. Comparing to other directional logging tools investigated before, the presented tool has a simple structure, but has a good directivity. Fundamental characteristics of this tool was theoretically investigated. The Born approximation, i.e., a conventional geometrical factor which has been widely used for the analysis of a induction logging system was generalized to tilt coil arrangements and was applied. The effect of tilt angle, coil separation and operation frequency were studied. A prototype model of the presented tool was fabricated and tested in a formation model. This model has inclined boundaries of formations having different conductivities. The measurement shows that this tool has a directional sensitivity as is expected from the theory. It was found from the theoretical analysis and experimental measurements that this system can measure the true resistivity of each formation as the conventional induction logging systems, and additionally it can make deep azimuthal resistivity measurement.
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M3 - Paper
AN - SCOPUS:85037664732
T2 - SPWLA 35th Annual Logging Symposium 1994
Y2 - 19 June 1994 through 22 June 1994
ER -