This work is an attempt to solve emulsion problem in the petroleum industry, Researcher who are performing phase behavior studies under reservoir conditions (High Pressure and Temperature) faces that problem. Using chemical additives which called emulsion breakers is the common way to separate crude oil and free the formation water from the emulsion. Emulsion is naturally occurring during the oil production. There are two kind of emulsion Oil-in-water and water-in-oil. Stability of the emulsion may depends on the nature of crude oil and the extent of the accompanied water during the production. Demulsification process is breakage the emulsions using materials which have surface activity. This Book Discuss Preparation Of Some Polymeric Demulsifiers ( Emulsion Breakers ) To Solve Waxy and Asphaltenic Crude Oil Emulsions Problems While Conducting Phase Behavior Studies Under Sever Phase Conditions Of Pressure, Volume and Temperature.