O One of the artificial lift methods widely applied under such conditions is the hydraulic pumping unit (hpu) due to its operational flexibility and suitability for wells with low reservoir pressure and high water content. however, in practice, hpu performance is often suboptimal because of a mismatch between pump capacity and reservoir inflow capability, resulting in low volumetric efficiency and failure to achieve the well’s production potential. this study was conducted on wells r-33, p-22, and k-30 in the bun field, which represents a mature oil field with saturated reservoir conditions, where reservoir pressure (pr) is lower than bubble point pressure (pb) and fluid production is dominated by a multiphase oil–water flow system. reservoir inflow performance was analyzed using the wiggins inflow performance relationship (ipr) method. this study were to evaluate pump displacement, pump volumetric efficiency, and mechanical safety aspects of the system, as well as to determine potential production improvements through optimization of pump operating parameters, namely stroke length and pump speed (spm). the evaluation results indicate that under actual operating conditions, well r-33 has a pump displacement of 194.53 bfpd with an actual production rate of only 69.6 bfpd, resulting in a volumetric efficiency of 35.78%. in well p-22, pump displacement reaches 475.50 bfpd while the actual production rate is 104 bfpd, yielding a lower volumetric efficiency of 21.87%, which indicates an under-filled pump condition. in contrast, well k-30 exhibits relatively better performance with a pump displacement of 132.40 bfpd, a production rate of 90.6 bfpd, and a volumetric efficiency of 68.43%. mechanical safety analysis based on peak polished rod load (pprl) and minimum polished rod load (mprl) shows that although wells r-33 and p-22 experience considerable load fluctuations, all calculated stresses remain below the allowable material limits. after optimization, volumetric efficiency increased to 89.12% in well r-33 and 90.36% in well p-22, accompanied by production rate increases to 102.5 bfpd and 169.5 bfpd, respectively. these results demonstrate that optimization of hpu operating parameters can significantly improve production performance while maintainings mechanical safety and operational sustainability without requiring major equipment replacement.