When drilling operations commenced in Sao Francisco basin, the operator knew the exploratory well campaign would present a major investment. However, as operations progressed the well costs and time exceeded assessments mainly drilling the 8½? production hole section through two hard and abrasive formations. Due to the unconventional nature of the reservoir, well costs must be held to a minimum in the exploration phase to ensure each project is economically viable. To accomplish the objective, several tool technologies were analyzed and proposed with the aim of reducing down-time and tool failures. One of the main issues identified was the high level of shock and vibration (S&V) observed while drilling the Macaubas and Paranoa formations. The environment had a negative impact on drilling efficiency and contributed to tool failures and excessive wear on BHA components leading to additional trips and preventing the operator from achieving higher ROP and run lengths.

After an engineering analysis, the drilling team determined the root cause was BHA/bit whirl while along with several other contributing factors related to the challenging hard and abrasive formations. Based on this information, the provider recommended using a roller reamer in the bottom hole assembly (BHA), to mitigate shock and vibration and improve drilling efficiency. Results were positive and the roller reamer reduced NPT and overall well costs in this economically sensitive play. Roller reamers are currently part of standard packed BHA and are being used as a reference for operators experiencing the same type drilling dysfunctions.