Abstract During extended reach drilling operations, stick-slip was identified within the operator's Fast Drill Process™ workflow as the primary performance limiter in the 8-1/2-in. hole section. This dysfunction resulted in low penetration rates, frequent downhole tool failures, and bit damage. Subsequently, multiple bit runs were required to reach interval objectives.
The redesign process identified two key solutions to mitigate stick-slip vibrations. First, the bit was redesigned to limit (or manage) the depth of cut to reduce the torque variations which can excite stick-slip. Second, the torsional stiffness of the drillstring was increased by changing from 5-1/2- to 5-7/8-in. drillpipe, which reduced the magnitude of the torsional oscillations. The systematic application of these design changes allowed higher weight on bit (WOB) to be applied without stick-slip dysfunction, resulting in significantly higher penetration rates.
This paper presents the results of applying depth of cut control and drillstring design to eliminate stick-slip while drilling. Weight-on-bit, vibration, and penetration rate data will be presented over the course of eight wells. Results indicate the managed depth of cut and increased torsional stiffness provided significant reductions in vibrations leading to multiple field record rate of penetrations (ROPs), improved downhole tool life, and reduced bit damage.
Introduction The Hibernia Platform (Fig. 1) is a gravity based structure (GBS) located in the Jeanne d 'Arc Basin off the coast of Newfoundland, Canada (Fig. 2). The GBS accesses two oil reservoirs, Hibernia and Ben Nevis-Avalon (BNA), through extended reach drilling (Fig. 3). Drilling from the platform has been conducted to measured depths as far as 33,000-ft MD, accessing the Hibernia and BNA reservoirs at approximately 12,100-ft TVD and 7,900-ft TVD, respectively. Wells drilled from the platform are typically S-shaped and have three dimensional trajectories with 12-1/4-in. tangent sections as long as 16,500-ft MD and sail angles between 35° and 84° (Fig. 4).
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