Constructing a fine 3D geomodel for complex giant reservoir is a crucial task for hydrocarbon volume assessment and guiding for optimal development. The case under study is Mishrif reservoir of Halfaya oil field, which is an Iraqi giant carbonate reservoir. Mishrif mainly consists of limestone rocks which belong to Late Cenomanian age. The average gross thickness of formation is about 400m. In this paper, a high-resolution 3D geological model has been built using Petrel software that can be utilized as input for dynamic simulation. The model is constructed based on geological, geophysical, pertophysical and engineering data from about 60 available wells to characterize the structural, stratigraphic, and properties distribution along the reservoir. Fourteen geological surfaces for all Mishrif units have been generated based on well tops data and top Mishrif structural map. The reservoir has been divided into 163 sublayers through the vertical direction and 160*383 grid cells in x-y direction with 9,988,640 total grid cells. A scale up process are performed for well log data, then, Sequential Gaussian Simulation algorithm are applied to fill 3D grid cells with properties values in areas away from wells. Pertophysical properties distribution for all reservoir zones are analyzed. The estimated initial oil in place of Mishrif through this model is close to that calculated in other previous studies.
