In both Rumaila and Zubair fields, operators were challenged by declining injector and producer performance in sandstone intervals characterized by high clay content, HCl-sensitive minerals, and carbonates. Conventional multistage acid treatments required complex fluid sequences and extended pumping time, increasing exposure to precipitation, fines migration, and corrosion risks. Sustained injectivity improvements were difficult to achieve, particularly in the upper shale intervals in Rumaila, where near-wellbore damage and brine-related impairment limited performance.
Previous stimulation attempts using legacy multistage acid systems yielded inconsistent results, with limited durability of injectivity gains and operational inefficiencies due to large fluid volumes and equipment footprint. Customers were seeking a lower-risk, simplified approach capable of restoring permeability while minimizing secondary formation damage and logistical exposure—especially in rigless execution windows in Zubair.
The primary objective was to restore injectivity and production performance in complex sandstone reservoirs while reducing operational risk, simplifying execution, and enabling repeatable deployment across candidate wells.
SLB deployed the OneSTEP EF solution to directly address the mineralogical complexity of clay- and HCl-sensitive sandstone intervals while eliminating the multiple interfaces inherent in conventional multistage acid systems. By consolidating all treatment functions into a single-stage application, the solution reduced precipitation risk, minimized formation exposure time, and simplified surface logistics—critical for both injector rehabilitation in Rumaila and rigless campaign execution in Zubair.
In Rumaila, the first OneSTEP EF solution deployment delivered:
These results restored injector performance and improved near-wellbore conditions while reducing the risks associated with conventional acidizing, including precipitation, fines migration, and corrosion. The simplified single-stage approach also reduced operational complexity and enabled a more controlled, repeatable execution model across similar wells.
In Zubair, integration of the OneSTEP EF solution within the first rigless campaign reestablished access to stimulation in constrained operational environments. The simplified fluid system and reduced equipment footprint enabled faster execution and improved operational efficiency within rigless windows.
The November 2025 pilot phase informs a structured rollout strategy, supporting standardized, low-risk sandstone treatments across prioritized wells. This establishes the OneSTEP EF solution as a scalable stimulation pathway for clay-sensitive sandstone intervals, enabling consistent performance improvement while minimizing operational exposure.
