Increase ROP in hard formation with turbodrill and hybrid bit
Schlumberger recommended using a 9 1/2-in T112HF steerable Neyrfor
Traditional standard turbodrill to drive an impregnated hybrid bit with 16-mm
PDC cutters. This combination, which was selected based on hydraulic
calculations, significantly increased ROP and reduced drilling time. The bent
housing on the turbodrill’s bearing section was set at 0.75° to
perform any directional work required to maintain the planned trajectory, and
the turbodrill was configured with a 121/8-in lower bearing stabilizer (LBS)
and a 12-in midbody stabilizer (MBS) to hold inclination and azimuth. In
addition, there was an 11 3/4-in stabilizer on the MWD tool above the
turbodrill.
Increased ROP and reduced drilling time, saving USD 4 million
The steerable Neyrfor Traditional turbodrill and impregnated hybrid bit
achieved an average ROP of 4.7 m/h in the hardest interval of the 12¼-in
section, which is 88% higher than the 2.5 m/h average ROP from the RSS and PDC
bit in the previous interval. The performance improvement in the 250-m interval
saved the operator nearly two days of drilling time and approximately USD 4
million.
The first 212 m of the 12 1/4-in section, from 3,211 m to 3,423 m MD,
were drilled at an average ROP of 2.5 m/h using a BHA with a PDC bit and RSS.
At that point, inclination was 45.83° and azimuth was 221.1°. A trip
was then made to change to a BHA with the steerable turbodrill and hybrid bit
to drill the claystone and limestone formation—considered the
section’s hardest interval.
The turbodrill BHA then drilled 250 m through the hard upper formation
at an average ROP of 4.7 m/h. Throughout the run, inclination and azimuth were
held at 45.79° and 222.36°, respectively, per the well plan, with just
33 m spent sliding. After reaching the lower formation at 3,673 m MD, a trip
was made to change back to the BHA with the RSS and PDC bit because the
formation was softer than the upper one.
