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Field Distortion Due to Surface Pipes in Surface to Borehole Electromagnetic
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 78th EAGE Conference and Exhibition 2016, May 2016, Volume 2016, p.1 - 5
Abstract
Surface to borehole (STB) and borehole to surface (BTS) EM measurements are expected to provide useful resolution of the oil/water contact at reservoir depth. It has been shown however that the effect of the vertical steel casing above the reservoir can yield a distortion of the fields due to current channeling and leakage away from the casing. This paper extends the analysis of casing effect to investigate the channeling arising when the exciting source induces currents in pipes that extend horizontally in front of dipolar antennas. The problem considers a halfspace system (air-sediments or seawater-sediments), a pipe buried in the lower medium extending along the Y axis and a horizontal dipole source embedded in the upper medium. The problem is treated in a semi-analytical formulation, providing a general framework to study the current channeling effect in the pipe and in turn to compute the secondary vertical electric and magnetic field arising downhole due to an exciting dipole source oriented in the X and Y direction.