The petrophysical characteristics of five wells drilled into the Sa'di Formation in the Halfaya oil field were evaluated using IP software to determine a reservoir and explore hydrocarbon reserve zones. The lithology was evaluated using the M-N cross-plot method. The diagram showed that the Sa'di Formation was mainly composed of calcite (represented by the limestone region) is the main mineral in the Sa′di Reservoir. Using a density-neutron cross plot to identify the lithology showed that the formation mainly consists of limestone with minor shale. Gamma-ray logs were employed to calculate the shale quantity in each well. The porosity at weak hole intervals was calculated using a sonic log and neutron-density log at the reservoir unit. Additionally, Archie's equation is applied to calculate fluid saturation using resistivity data. The reservoir water saturation in the uninvaded zone is calculated using Archie's equation, which determines the most essential element utilized in log evaluation. Finally, the permeability was measured using a flow zone indicator. The results indicate that the limestone and shale that the cuttings description report enhanced comprise most of the Sa'di reservoir. At the HF-316 and HF-21 wells, the core porosity was verified. In an uninvaded zone, the Archie equation offers the best estimation. Three equations were derived from the core data's porosity-permeability connection using a cross-plot of the reservoir quality index and normalized porosity index. According to the general interpretation, zones B1, B2, and B3 contain the most hydrocarbons; however, the B2 zone, the best layer in the Sa'di reservoir, has the highest hydrocarbon concentration. This is close to previous studies and field results. Finally, Sa'di A is formed mainly of mud lime and contains no hydrocarbons. As a result, Sa'di A was separated into A1 and A2 based on the percentage of shale difference.