Development of 3D Geological Model and Analysis of the Uncertainty in a Tight Oil Reservoir in the Halfaya Oil Field

A geological model was built for the Sadi reservoir, located at Halfaya oil field. It is regarded as one of most significant oilfields in Iraq. The study includes several steps, essential which importing well logs from six wells to Interactive Petrophysics software conducting interpretation and analysis calculate petrophysical properties such permeability, porosity, shale volume, water saturation, NTG then maps tops Petrel build 3D-Geological value original place. Three surfaces were produced all units based on well-top data top structural map. reservoir has been divided into 85 sublayers vertical direction 170*143 grid cells x-y direction, totalling 2,066,350 cells. Sequential Gaussian Simulation technique used fill 3D with property values locations far after upscaling log data, distributed across zones. standard place calculated, uncertainty evaluation obtain more accurate results. Model Risk Analysis employs Monte Carlo generate pessimistic, likely, optimistic reserve (P90, P50, P10). affected by formation volume factor, depth, (porosity, NTG), geometric structure (horizons zones).