This paper discusses ultradeep directional-resistivity (DDR) logging-while-drilling (LWD) measurements for high-angle and horizontal wells that have been applied recently with success on the Norwegian continental shelf (NCS). The main benefits from the DDR measurements in the license have been to maximize reservoir exposure by active geosteering, optimize well placement above the oil/water contact (OWC), and increase subsurface understanding.
Background
More than 50% of all production wells today on the NCS are highly deviated or horizontal. An operator has tested DDR measurements since 2009. This new while-drilling technology, with its increased depth of investigation and ability to interpret multiple boundaries above and below the wellbore, is regarded as a key technology in reaching the ambitious target recovery rate of 70%.
Fig. 1 presents the bottomhole-assembly (BHA) architecture for the first DDR LWD tool with depth of investigation in excess of 30 m away from the borehole. The tool architecture consists of a set of subs spaced out on a BHA providing multispacing, multifrequency azimuthal measurements.
