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Abstract While conducting a wells campaign in North Brazil, the Operator suffered from significant non-productive time in the 8 ½-in deviated intermediate hole section, caused by BHA component failures while drilling hard diabase rock layers. Based on this outcome, an integrated Wells-Contractor team devised a plan to deploy new tools and technologies to efficiently drill the intermediate hole section in a single run, while controlling/mitigating shocks and vibrations, and preventing the re-occurrence of tool failures. The strategy encompassed a detailed engineering analysis to refine the drilling system, integrating new tech PDC bits with geometrical cutting structure, an at-the-bit sensor module for downhole dynamics recording, a more robust mud motor technology, and an instrumented sub for real-time high-frequency downhole dynamics monitoring. For the initial implementation, a 3-well sequence was selected to map the frequency and magnitude of shocks and vibrations throughout the area of operations, thus contributing to an enhanced understanding of the phenomenon for further modeling of the most suitable drilling system to address the challenges of the section. From the outset, well 4 had immediate significant improvement, with the first 8 ½-in BHA drilling through over 200 meters of diabase rock, more than doubling the meterage of the previously longest recorded run in well 3 and keeping drilling dynamics and tool integrity concerns in check. For the next 2 wells, the team further capitalized on the success of the refined BHA. Enticed by performance in well 4, the team started deepening the intermediate hole section to accommodate specific well design requirements. In well 6, the first BHA drilled through 328 meters of diabase rock, slightly surpassing the single BHA run meterage from the previous well and improving ROP. And in well 7, a single BHA drilled 1062 meters "shoe-to-shoe", including 300 meters of diabase rock, yielding a 33% ROP improvement against the average of the previous 2 best-performing wells. On a shoe-to-shoe basis, the implementation yielded a significant 100% performance improvement in the overall section meterage rate compared to the previous campaign. This, in turn, contributed to a 50% reduction of the effective metric cost and reduced risk exposure by eliminating trips and associated BHA handling. Well construction activities in North Brazil have their share of logistical and technical challenges. For the latter, the systematic integration of fit-for-purpose technologies and downhole measurements enabled the team to finally crack the code of hard rock drilling performance and dynamics in the Eastern Amazon basin, thus yielding great overall value for the project. As a result, the Operator plans to carry on the momentum and promote the next well design-related step changes across the region.
Quiñones et al. (Fri,) studied this question.