Stick/slip prone formation threatens operation viability
While trying to drill 8 1/2-in well sections for a well in offshore Malaysia, an operator was experiencing problematic torsional vibration caused by a stick/slip-prone formation.
To increase operational progress, a Schlumberger drilling design team initiated an i-DRILL system design analysis to develop a BHA that would mitigate vibration and enhance drilling performance. The team divided their analysis into three parts.
1: Drilling data analysis. Drilling data that included drilling parameters,
mud logs, dull pictures, and drilling reports from the from the first two wells were analyzed. Understanding the formation properties and how the bit behaved in the formation was enhanced through the use of
DBOS optimization analysis. The data identified potential contributors to the drilling performance problem: interbedded formation, hard stringers, washouts in the hole, insufficient lubricity with
water-based mud (WBM), and the use of a
reaming stabilizer tool.
2: IDEAS platform analysis. To further investigate the operator’s problem, the IDEAS drillbit design platform was used to simulate drilling conditions that matched the application in which a BHA would be used. This effort revealed that the reaming stabilizer tool, which was initially used to help remove ledges, caused very high levels of lateral and torsional vibration. Accordingly, the BHA would perform much better and much more stable with a regular stabilizer instead of the reaming stabilizer tool.
