A Master thesis titled Tar-mat origin, identification, distribution and geochemical characteristics from Zubair Formation in West Quran 1 oilfield southern Iraq was defended at College of Science, Department of Geology for the postgraduate Candidate Haneen Mahdi Jassim. The aim of the thesis is Identification of the tar mat zones in Zubair Formation/West Qurna oilfield, and determining the depths and thicknesses of these zones. Determination of geochemical properties of tar mat via geochemical analysis. Determine mechanism occurrence of tar mat in reservoirs. Study content: The study included several stages, including the collection of samples and data from cores, well logs, the description of the core, and the study of the behavior of resistivity and NMR logs for the identification of tar mat. In addition, the review of the final geological reports, and the previous studies. Geochemical analysis was conducted on core and crude oil samples to know the geochemical characteristics of hydrocarbons and calculate the petrophysics characteristics of the reservoir.