Impact of Selectivity Loss on Scale Management in Well-F in the Buzios Pre-Salt Field: Insights into Crossflow Effects and Operational Challenges

Abstract This study examines the effects of selectivity loss on scale management and production efficiency in Well-F, situated within the Buzios Pre-salt field and equipped with intelligent completion inflow control valves. The research aims to elucidate the role of crossflow phenomena, identify the underlying mechanisms contributing to productivity decline, and evaluate targeted mitigation strategies to optimize well performance. The Buzios reservoir, notable for its extensive carbonate sequences and multi-interval well architecture, presents distinctive challenges that necessitate a multidisciplinary approach to formation damage management. To investigate these challenges, advanced diagnostic methodologies were employed, including productivity index trend analysis, skin factor evolution, diagnostic plotting, and pressure loss assessment using Permanent Downhole Gauge (PDG) sensors. These techniques yielded significant insights into reservoir dynamics and the impact of crossflow, both of which critically affect production efficiency. Two principal mechanisms of productivity impairment were identified: (1) an abrupt decline resulting from the malfunction or unintended movement of the intermediate control valve (ICV-ITM), and (2) a gradual decrease attributed to carbonate scale deposition. The abrupt productivity drop observed in early 2023 was linked to an unexpected partial closure of the ICV-ITM, leading to a marked reduction in output from the intermediate interval and challenging the presumption that intelligent completions inherently facilitate scale diagnostics. In contrast, the gradual loss in productivity due to carbonate scaling was addressed through a combination of acid stimulation and inhibitor squeeze treatments. These chemical interventions proved both cost-effective and operationally efficient, though crossflow effects constrained the extent of productivity recovery. Despite only partial restoration following chemical treatments in late 2022, the reopening of the ICV-ITM in late 2023 resulted in the full recovery of well productivity, underscoring the importance of proactive equipment maintenance. Overall, this study highlights the complexities associated with managing scale-related formation damage in high-productivity pre-salt carbonate reservoirs. It emphasizes the critical need to integrate advanced diagnostic tools, customized chemical treatment regimes, and proactive maintenance strategies to effectively address productivity challenges. Furthermore, novel findings regarding the application of PDG sensors and interval-specific remediation underscore actionable approaches for enhancing production efficiency and maintaining integrity in complex reservoir environments.