Net-Pay Optimization and Improved Mapping With Look-Around LWD Measurements

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 171856, “Net-Pay Optimization and Improved Reservoir Mapping From Ultradeep Look-Around Logging-While-Drilling Measurements,” by Frank Antonsen, Per Atle Olsen, Stein Ottar Stalheim, Monica Vik Constable, Matthieu Irondelle, Michael Cook, and Trond Rognebakke Bjørstad, Statoil, and Christophe Dupuis, Philippe Marza, Jean Seydoux, Dzevat Omeragic, and Jean-Michel Denichou, Schlumberger, prepared for the 2014 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 10–13 November. The paper has not been peer reviewed. 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. With these measurements, a multilayer inversion generates a mapping of the resistivity distribution above and below the borehole. Differentiating this technology from standard image logs, the relative dip of the formation layer can be determined not only at the trajectory, but also away from the trajectory. In addition to the 1D (layer-cake) resistivity mapping, the tool provides an orientation of the map perpendicular to the formation-structure planes.