Petrophysical Evaluation and Preliminary Flow Quality Ranking of the Faroud Member Using Well Logs: Al-Zanad Field, Sirt Basin, Libya

Abstract

This study evaluates the petrophysical properties and provides a preliminary ranking of flow quality for the Faroud Member, Al-Zanad Field, Sirt Basin, Libya, using interpreted results from wells VVV4, VVV5, and VVV12. The confirmed log suite comprises gamma ray (GR), bulk density (RHOB), neutron porosity (NPHI), and resistivity. Reported parameters include shale volume, total and effective porosity, secondary porosity, water saturation, estimated permeability, net petrophysical thickness, hydrocarbon pore-volume thickness (HPV), and reservoir quality and flow-zone indicators (RQI and FZI). Effective porosity ranges from 16.70% to 23.10%, whereas estimated permeability ranges from 47.82 to 2666.55 mD. Well VVV12 has the lowest water saturation (49.40%) and the highest estimated permeability (2666.55 mD), and it yields the highest calculated RQI and FZI. Well VVV5 has the greatest net petrophysical thickness (40 ft) and HPV (3.148 ft). Although VVV4 has the highest reported total and effective porosity and secondary porosity, it is a dry well and has the lowest estimated permeability and the highest water saturation among the three wells. This contrast demonstrates that porosity alone does not establish effective flow quality or prove hydrocarbon occurrence. The preliminary flow-quality ranking based on estimated permeability, RQI, and FZI is VVV12, followed by VVV5 and VVV4. The ranking remains indicative because permeability is model-derived, core calibration is unavailable, and the RQI/FZI values were calculated from well-average data.