Reservoir top detection by resistivity logging signals in deviated and horizontal wells: comparative analysis

This research is aimed at finding out the capabilities of an electromagnetic probe with toroidal coils in geosteering problems. Three-dimensional numerical finite-difference modeling of electromagnetic responses was performed for a probe with toroidal coils, for high-frequency electromagnetic logging probe and side logging sondes in two-layer models with varying resistivity contrast and borehole zenith angle. Based on these calculations, the key features of the toroidal coil electromagnetic sounder (ZET), high-frequency electromagnetic logging (VIKIZ) and side logging (BKZ) signals in detecting the boundary before it is crossed are shown. These features make it possible to determine the approach to the roof of the collector using the signals ZET, VIKIZ and BKZ.