Numerical simulation of multilateral wells affected by geometrical design for oil production optimization. A case study from one of Iran’s oil fields

Multilateral wells (MLW) offer considerable potential for improving oil recovery by increasing reservoir contact; however, the production response to different combinations of key design parameters can vary with well configuration and reservoir conditions. The present study focuses on evaluating the combined effects of lateral number, lateral length, branch-angle configuration, and lateral placement using a reservoir model developed from field data from an oil reservoir in the Dezful embayment, southwest Iran. A three-dimensional (3D) geological model was constructed in FloGrid and subsequently integrated with a dynamic reservoir simulation in Eclipse 100 based on the black-oil formulation. Fluid properties were characterized in the pressure-volume–temperature interactive (PVTi) module using the Peng–Robinson (PR) equation of state. The performance of multilateral well configurations was then evaluated against that of a conventional vertical well. The results showed that the three-lateral well delivered the highest cumulative oil production, whereas the opposed dual-lateral well exhibited a more stable production profile with a lower water cut. Increasing lateral length enhanced production performance, and a lateral length of 1500–2000 ft is recommended as a practical design range for reservoirs with characteristics similar to those investigated in this study. In addition, an asymmetric branch‑angle configuration combined with laterals positioned on the same side of the main well produced the most favorable production response among the investigated scenarios. Overall, the findings demonstrate that multilateral well performance is controlled by the combined effects of lateral length, branch-angle configuration, and lateral placement rather than by the number of laterals alone, providing a practical basis for the selection and design of multilateral well configurations in reservoirs with comparable characteristics.