T This study discusses the physical and chemical properties and types ofscales in three formation water samples X, Y, and Z. Formation of X, Y, and Zwater was tested in the Reservoir Fluid Analysis Laboratory to determine thephysical, chemical, and type of scale properties. The data of the three X, Y, and Zformation water samples were taken from PT Pertamina Tambun. The physicalproperties of water samples formation X, Y, and Z are SG with a range (1.0144 -1.0161), density range (1.0133 - 1.0151) gr / cc, total solid range (0.0205 -0.0225) ppm, organic matter range (633.58 - 666.76) ppm, and the viscosity in thewater sample drops when the temperature rises.The chemical characteristics of formation of X, Y, and Z are pH in therange (7.05 - 7.17), composition of Ca in the range (54.88 - 141.12) meq / l,composition of CO3 in the range (0.64 - 1.23) meq / l, and SO4 composition inthe range (1.47 - 2.06) meq / l. The three formation water samples were used inmeasuring Calcium Carbonate using the Stiff & Davis method obtained SI valuesin samples X, Y, and Z respectively at 6.538, 6.79, and 6,913 so that samples ofX, Y, and Z can be concluded all samples formation water contains CalciumCarbonate scale. Skill, McDonald's, and Stiff methods are used to determine thescale of Calcium Sulfate obtained by the value of S in the formation of watersamples X, Y, and Z respectively in meq / l are 18,012, 37,189 and 24.28. The Cavalues in the formation of X, Y, and Z water samples in meq / l are 141.12, 61.15,and 54.88 so it can be concluded that the water samples of X, Y, and Z formationsdoesn’t contain Calcium Sulfate.