The ultimate goal of the reservoir geophysicist is to determine the reservoir properties (lithology and porosity) and conditions (pore fluid and pressure) from seismic data. This goal can be achieved by applying rock physics transforms to a volume of seismically-derived elastic properties. The basis for establishing rock physics transforms are controlled experiments where the reservoir and elastic sediment properties are measured on the same sample of reservoir under the same conditions. Such experimental data come from well logs and cores. The purpose of this paper is to apply rock physics diagnostic to well log data from the Asmari reservoir in Mansuri oil field and then used to quantify porosity from acoustic impedance inversion volumes. The results show that Nur-Dvorkin (1996) model and Raymer-Greenberg-Castagna (1997) are good for predicting porosity in sandstone and the carbonate zone of the Asmari reservoir respectively.