Acidizing Heterogeneous Pre -Salt Carbonates Offshore Southeast Brazil

Abstract Achieving effective treatment coverage in long, high-permeability carbonate intervals remains a challenging objective, and Petrobras’ Pre-Salt offshore fields in Brazil are no exception. Wells are typically completed as open holes with two or three intervals isolated by feed-through packers, and flow is regulated through Interval Control Valves (ICVs). Each interval can extend beyond 200 meters, and when combined with permeability contrasts, acid diversion becomes particularly complex. To address these challenges, Petrobras has implemented various strategies to refine stimulation techniques and mitigate risks while maintaining operational efficiency. Given the selective completion of intervals, the use of coiled tubing and wireline introduces additional operational complexity, cost, and risk. Consequently, a novel mechanical solution was introduced: electronic remote-actuated valves installed at the base of the interval, complementing the intelligent completion valves located at the top by enabling acid injection from two distinct points. The depth of the secondary valve and the pumping strategy are optimized based on permeability log analysis, thereby enhancing zonal coverage compared to single-point injection. This approach has demonstrated a significant return on investment by improving treatment distribution without compromising operational safety or reliability. As a result, the deployment of these valves is expected to expand across new well projects, ultimately increasing treatment coverage and enhancing oil recovery in these fields.