Density and viscosity are of the most important governing physical parameters of the fluid flow, either in the porous media or in pipelines. Ideally, density and viscosity determined experimentally in the laboratory on actual fluid samples taken from the field under study. However, in the absence of experimentally measured data, especially during the prospecting phase, or when only invalid samples are available, one can resort to empirically derived PVT correlations. The main objectives of this study are firstly, collecting experimental samples which involve one thousand (1000) fluid samples covering a wide range of crude oils ranging from heavy to volatile oils. Secondly, conducting PVT analysis at reservoir temperature and at different pressures to determine oil density and oil viscosity at reservoir temperature and different pressures, then develop novel empirical correlations. This book involve four main chapters; introduction, literature review, material and Methods, and finally Results and discussions. This work may be valuable for Petroleum engineers and candidates interested in petroleum industry and fluid physical properties.