Published: 01/19/2015
Published: 01/19/2015
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.
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%.
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.
Challenge:
Solution: Run a Rhino XS2 full-cycle expandable reamer and a roller reamer to increase wellbore quality while enlarging the hole.
Results:
