<![CDATA[Mature oil fields commonly face production decline, increasing water cut, and limited availability of complete static and dynamic reservoir models. Under these conditions, a practical and traceable workflow is necessary to select well candidates for production optimization. This study proposes an integrated workflow combining well opportunity index (WOI), Delta Potential, quadrant analysis, and weighted ranking. The workflow is applied to three producing wells in the G-40 sandstone reservoir of the TM Field, a mature oil field in the South Sumatra Basin, Indonesia. Current oil saturation is estimated using a fractional-flow-based approach and validated by matching calculated and observed oil rates, resulting in Mean Absolute Percentage Error (MAPE) values of approximately 2%, 3%, and 3%. WOI represents reservoir opportunity through flow capacity, movable hydrocarbon pore volume, and remaining pressure support, while Delta Potential quantifies remaining production opportunity. The calculated Delta Potential values are 0.112, 0.103, and 0.042 MMSTB for TM-1, TM-2, and TM-3, respectively. Quadrant analysis places TM-1 and TM-2 in the high-WOI and high-Delta-Potential region; however, TM-2 is treated as a secondary candidate requiring further diagnosis because its WOI is lower than that of TM-1. The final weighted ranking produces the priority order TM-1 > TM-2 > TM-3. These results indicate that the proposed workflow provides a practical and traceable preliminary screening tool for mature-field production optimization under limited data availability.]]>
