Case Study: First Rhino RHE System Run in Deepwater Brazil Saves Petrobras USD 1.4 Million, Reduces Rig Time 21%

Dual-reamer solution eliminates rathole and allows setting casing in specific target formation, saving a dedicated trip and improving operational efficiency

Challenge: Decrease rig time and improve efficiency during a deepwater hole-enlargement-while-drilling (HEWD) program offshore Brazil.

Solution: Run the Rhino RHE dual-reamer rathole elimination system, which would enlarge the hole section and eliminate the rathole.


  • Enlarged 3,996 ft [1,218 m] of borehole from 12 1/4 in to 14 3/4 in.
  • Enlarged 167 ft [51 m] of the 177-ft [54-m] rathole without a dedicated cleanout run.
  • Saved a dedicated trip by setting casing in the target formation, which could not be reached without eliminating the rathole.
  • Saved USD 1,400,200 and reduced drilling time by 21%.
  • Maintained vertical trajectory by using optimized parameters.

Minimize drilling time in deepwater exploration campaign

While drilling exploration wells in a presalt field offshore Brazil, Petrobras required enlarging the 12 1/4-in hole to 14 3/4-in for casing clearance purposes. After successfully enlarging the borehole, the operator set a 10 3/4-in casing below the end of a halite package in the anhydrite formation to enable more accurate results during the leakoff test for the next hole section.

This approach requires a dedicated cleanout run to remove the offset between the underreamer tool and the 12 1/4-in bit. However, a dedicated cleanout run necessitates increased drilling time because the HEWD BHA must be pulled out of hole to allow running an underreamer-only BHA to enlarge the offset area between TD and the underreamer.

Integrate dual-reamer solution into HEWD BHA

For avoiding adding extra time to the drilling operation, Schlumberger recommended that Petrobras use the Rhino RHE system, an integrated dual-reamer drilling system that enlarges the borehole while drilling and eliminates the rathole without requiring a separate trip. The Rhino RHE system comprises a Rhino XS hydraulically expandable reamer, which was run above MLWD tools, and a near-bit Rhino XC on-demand hydraulically actuated reamer. Once the BHA reached TD, the Rhino XC reamer was activated and enlarged the rathole, eliminating the need for a dedicated rathole cleanout run. Because the well was gaining inclination and no rotary steerable system was used in the BHA, Schlumberger and Petrobras worked together to manage drilling parameters and to control the well trajectory.

Save USD 1,400,000, reduce drilling time by 21%

This operation marked the first Rhino RHE system run in deepwater Brazil. Petrobras enlarged the interval from 14,321-ft [4,365-m] MD to 18,317-ft [5,583-m] MD, a total of 3,996 ft [1,218 m], using the Rhino XS reamer. The average ROP was recorded at 38.4 ft/h [11.7 m/h]. Once the BHA reached TD, the Rhino XC reamer was activated, and the borehole was enlarged from 18,150-ft [5,532-m] MD to 18,317-ft [5,583-m] MD, thereby removing the offset between the Rhino XS reamer and the drill bit. For this operation, ROP averaged 9.8 ft/h [3 m/h]. Throughout the operation, drilling parameters were monitored and optimized to ensure correct trajectory.

After completing the HEWD job, the BHA was POOH, and the cutter blocks of both reamers were found to be in gauge. By using the Rhino RHE system, Petrobras reduced operational time by 21% and saved approximately USD 1,400,000.

Download: First Rhino RHE System Run in Deepwater Brazil Saves Petrobras USD 1.4 Million, Reduces Rig Time 21% (0.12 MB PDF)

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