Rhino XS2 Reamer Enlarges Seven Horizontal Sections in Horizontal Deepwater Wells

Published: 01/19/2015

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Enlarge horizontal sections in wellbore with complex stability issues

While drilling in deep water offshore Brazil, an operator had encountered wellbore stability issues in its horizontal wells. In one instance, the BHA became stuck in a tight hole and had to be cemented in. The operator wanted to overcome these problems by enlarging the horizontal section from 8 1/2 in to 9 1/2 in to allow more clearance when tripping the BHA in and out of hole. Enlarging the section would also allow tripping and running gravel-pack sand screens in the 8 1/2-in parent hole open lengths from 1,000 m to 1,400 m. Additionally, increasing annular clearances would improve ECD management.

Deploy Rhino XS2 reamer in customized BHA

The operator requested a tool that allows deactivation to prevent formation damage, to deter the creation of ledges and washouts, and to improve hole cleaning. Schlumberger recommended running a BHA that included the Rhino XS2 reamer, a hydraulically expandable reamer that permits one activation and one deactivation through a ball-drop method. This was the first time that the Rhino XS2 reamer was used in South America.

The Schlumberger team used the i-DRILL engineered drilling system design to evaluate different drilling mechanics issues and design a customized BHA, which included a roller reamer placed below the Rhino XS2 reamer. This configuration would avoid stick/slip and reduce surface speed as well as shock and vibration. i-DRILL system simulations showed that adding a roller reamer instead of an 8 1/2-in stabilizer below the Rhino XS2 reamer would help reduce stick/slip levels by 24%.

Enlarged an average of 1,100 m with no failures

While the reamer deactivated after enlarging all the horizontal sections an average of 1,100 m per run, the three bottom-up cycles were achieved in open hole, and one bottom-up cycle was achieved inside the 9 5/8-in casing. The average ROP of the seven total runs was 18 m/h. In all, seven hole enlargements were completed in seven runs with a 100% success rate, and the cutter blocks arrived at surface with little wear.

Graphic - The Rhino XS2 reamer  allows one activation and one deactivation through a ball-drop method.
The Rhino XS2 reamer allows one activation and one deactivation through a ball-drop method.
Brazil, South America, Offshore


  • Underream while drilling an 8 1/2-in × 9 1/2-in horizontal section to facilitate running gravel-pack sand screens, tripping in and out, and equivalent-circulating-density (ECD) management.
  • Provide underreamer deactivation at final enlargement section depth.

Solution: Run a Rhino XS2 full-cycle expandable reamer and a roller reamer to increase wellbore quality while enlarging the hole.


  • Successfully underreamed seven horizontal sections in seven runs.
  • Enlarged an average of 1,100 m with no failures.
  • Circulated four bottom-up cycles with successful tool deactivation in all runs.
  • Achieved average ROP of 18 m/h.
Products Used