The main objective of this article is to obtain reservoir properties, such as porosity, both at the well locations and in the interwell regions from seismic data and well logs. The seismic and well-log data sets are from an oil field in eastern Saudi Arabia, and the main target is a Jurassic carbonate reservoir. The geology of carbonate reservoirs in Saudi Arabia is well understood. Reservoir porosity estimation is essential and needs to be determined for flow simulation and reservoir management. A major component of this study is establishing the relation between the P-impedance and porosity using well-log data. An amplitude-versus-angle seismic inversion algorithm was used to invert the three-dimensional impedance volumes (i.e., P-impedance and S-impedance) given partial angle stacks of seismic traces representing reflection amplitude variations with angle of incidence. These impedance volumes were used to estimate porosity between the well locations. The seismic and log data provided a-priori information (i.e., the initial starting model and source wavelet estimate) necessary for obtaining geologically consistent results.