Improve drilling speed and efficiency in salt drilling
Shell wanted to design an optimized drilling system and identify best
practices that would set a new standard for Gulf of Mexico salt drilling. This
required a joint effort between Shell and Schlumberger to identify best
practices.
Use an optimized BHA design to achieve footage and ROP increases
Based on the analysis, a "drill on torque" approach was recommended to
maximize ROP in the salt. This would require increasing the torque limit to
65,000 ft.lbf while drilling salt. Consequently, it was suggested that the salt
drilling BHAs be designed with higher torsional stiffness to enable higher
torque and rpm without inducing harmful vibrations.
For the 16 1/2-in build-and-hold section, a combination of the
PowerDrive Orbit RSS from Schlumberger and the AxeBlade bit from Smith Bits, a
Schlumberger company, was recommended to enhance the drilling performance and
to widen the operating envelope, as compared with conventional PDC bits and RSS
systems.
Achieved new salt drilling benchmarks
The 18 1/8-in × 21-in section was drilled at 200 rpm with
65,000-lbf surface WOB, resulting in 200-ft/h [61-m/h] net ROP, and a maximum
instantaneous ROP of 300 ft/h [91 m/h]. This represents a 20% increase in ROP,
as compared with the best offset of 160 ft/h [49 m/h].
