A Master's thesis entitled (The Hydrogeochemistry of Water Injection and Its Effect on Petrophysical Properties of Upper Sand Member of Zubair Formation in West Qurna 1 Oil Field , Southern Iraq.) . Hold at the College of Science, Geology Department. The presenter (Zahraa Abdullah Muzaal) demonstrates the most important objectives of studying (Assessing the reservoir petrophysical characteristics include reservoir porosity, permeability, and pore throat system,  Diagnosing the physical, chemical, and biological properties of the water injection used in the Zubair Formation producing in the West Qurna oil field, Using chemical compatibility simulation to determine the compatibility between water injection and water reservoir, and Diagnosing the mechanism of formation damage by Mineral analysis of studied reservoir to evaluate the clay and non-clay minerals type and their impact on the reservoir.), The results reached (The effective porosity in Zubair formation is ranged from good to very good, The water saturation in Zubair formation increase toward north, The pore throat radius results in H and L units show that it ranges between Nanopores-Megapores due to heterogeneity in pore throat at studied wells, The best well unit for water injection is the H and L unit due to its good petrophysical properties, 6-Mineralogical analyses by XRD, SEM, and EDS of well core samples that were taken from the H and L unit indicated that Quartz is the predominant non-clay mineral, while Kaolinite with a minor amount of chlorite is the main clay mineral that reflected the permeability decline and formation damage possibility, The pH values results showed weakly acid to weakly acid - weakly alkaline for reservoir water formation and surface water samples respectively, that reveal non-effect on reservoir porosity and permeability, The chemical classification of the studied surface and injection water samples, such as Stiff, Piper, and Hydrochemical formula, show that they are of the Sodium Chlorite (NaCl) type.). The study recommends (Because bacteria and suspended material in injection water have such a large impact on the petrophysical properties and the formation damage they can cause, it is critical that the amount of hypo-chlorine (NaOCL), An alkaline water injection is not recommended in this research because it might cause salt deposition (scale) and, ultimately, a decrease in reservoir permeability. At the same time, Dammam's water may be used as an injection water in a certain ratio, however, there may have been a little amount of risk, Conduct a comprehensive investigation by using a Mineralogy study (XRD, SEM, and EDS) of the Zubair formation in the West Qurna 1 oil field.)