The initial oil in place (IOIP) is an important factor that controls economic planning for production and field life. Therefore, this parameter must be determined precisely and carefully. The present paper is dealt with study the impact of adopting two different strategies of property modeling on IOIP value. 3D geological model constructed by using information likewise: contour map, oil formation volume factor, control processing interpretation (CPI) of well logs, and well heads and tops of twelve wells for selected field. The chosen oil field is feeding from Mishrif reservoir and located in southern Iraq. Mishrif reservoir is classified to six layers: MA, MB11, MB12, MB21, MC1, and MC2. Two strategies for distributing petrophysical properties: porosity, water saturation, and net to gross thickness of Mishrif reservoir are utilized. The two strategies are sequential Gaussian simulation and moving average. The volumetric method is used for estimating IOIP values. The impact of using the two strategies of property modeling was very clear where the values of IOIP had a significant difference. The IOIP value of 3D model whose petrophysical properties are distributed using moving average strategy is 5.145 billion barrels, while the 3D model distributed by Gaussian strategy had IOIP equal to 4.195 billion barrels. According to obtained results, the choice of distribution method is very important in estimation of IOIP. Selection of optimal property modeling strategy need to statistical comparison with selected oil field reports and input data, so finally, the closest representation of a protective reservoir and accurate value of IOIP.