The Importance of the Geological Model for Reservoir Characterization Using Geostatistical Techniques and the Impact on Subsequent Fluid Flow

Abstract

ACKNOWLEDGMENTSWe thank Chevron Petroleum Technology Company for the permission to publish this material. We also thank the following colleagues at Chevron: K. L.Finger and S. R. Jacobson for supplying the biostratigraphic and geochemical interpretations used in this study; N. 1. Hancock for aiding the interpretation of lithologies from well logs; and D. S. McCormick for his critical review and comments of the manuscript. ABSTRACTFluid-flow simulation results are used extensively as reservoir performance predictions upon which to base economics for reservoir management decisions. The generation of numerical models for simulation purposes may be easily facilitated by computer-aided algorithms, regardless of the quality of data or input parameters, This study focuses on potentially erroneous conclusions deduced from simulator predictions if the simulation models are built without a sound geologic framework and the incorporation of seismic-based information, Models derived from two different correlation strategies, lithostratigraphic and chronostratigraphic, using well logs only are compared. Seismic inversions are included within the chronostratigraphic framework as a third model type. Histograms of breakthrough times indicate little difference between the well only models of either correlation strategy, whereas water displacement pattems are significantly different. Selection of the appropriate simulation results is closely tied to the reservoir management objective in question. Models which have been conditioned by the seismic pseudo-logs show substantially different results for both breakthrough and displacement distributions, and the spread or uncertainty in breakthrough estimates is greatly reduced compared to the log-only model results.A cloud transform method with correlated probability fields is introduced for stochastically estimating one model parameter (porosity) from another (impedance). This method allows incorporation of the scatter in the relationship between the two parameters (crossplot).References and illustrations at end of paper, 601

Construction of Comprehensive Geological Model for an Iraqi Oil Reservoir

“…This model characterizes the reference setting for computing the amount of hydrocarbons in the reservoir and forms the basis for the initialization of the dynamic model (Witter et al, 2016, Lerat et al, 2007, Al-Fatlawi et al, 2019b.The reservoir can only be produced once; then, it is unfortunate to select a position with low development situations. The practice of geological and reservoir models allows engineers to decide which development decisions deliver the safest and most cost-efficient development plan (Bashore et al, 1993, Cavero et al, 2016, Aziz and Hussein, 2021.…”