Abstract
Mature multilayer reservoirs frequently suffer from uneven zonal inflow, accelerated water breakthrough, and declining production efficiency under conventional commingled operation. This study investigates the effectiveness of simultaneous-separate production (SSP) in Field X by integrating a comparative before–after analysis with a field-based evaluation of hydraulic isolation performance. The implementation of SSP produced a distinct and stable improvement in well behavior, reflected in increased oil rates, reduced water cut, and a more favorable redistribution of drawdown toward deeper oil-saturated zones. These effects indicate that SSP successfully limits inflow from depleted, water-prone intervals while activating previously underperforming layers. To validate the robustness of the findings, the results were benchmarked against Tatneft’s large-scale SSP program, which demonstrates comparable production responses across hundreds of wells. The consistency between local and external outcomes confirms the reproducibility of SSP under varied geological settings. Overall, the study demonstrates that SSP is a technically reliable, operationally feasible, and economically justified method for managing vertical heterogeneity and enhancing recovery in mature Kazakh reservoirs. The results support broader deployment of SSP as a scalable strategy for prolonging field productivity and improving resource utilization.