P. Lemouzy, 1999. "Evaluation of Multiple Geostatistical Models Using Scaling-Up with Coarse Grids: A Practical Study", Reservoir Characterization—Recent Advances, Richard A. Schatzinger, John F. Jordan
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In the field delineation phase, the uncertainty in hydrocarbon reservoir descriptions is large. In order to quickly examine the impact of this uncertainty on production performance, it is necessary to evaluate a large number of descriptions in relation to possible production methods (well spacing, injection rate, etc.). The method of using coarse scaled-up models was first proposed by Ballin et al. Unlike other methods (connectivity analysis, tracer simulations), it considers parameters such as thermodynamic behavior of the fluids, well management, etc.
This paper presents a detailed review of scaling-up issues, along with applications of the coarse scaling-up method to various water-injection cases, as well as to a depletion case of an oil reservoir in the presence of aquifer coning.
The need for correct scaling-up of wellbore and near-wellbore parameters is emphasized and is far more important than correct scaling-up far from wells. I present methods to accurately represent fluid volumes in coarse models. I propose simple methods to scale-up the relative permeabilities, and methods to efficiently correct for numerical artifacts.
I obtained good results for water injection. The coarse scaling-up method allows the performance of sensitivity analyses on model parameters in a much lower computer time than comprehensive simulations. Models repre-senting extreme behaviors can be easily distinguished.
For the depletion of an oil reservoir in the presence of aquifer coning, however, the method is not as promising. It is my opinion that further research is required for scaling-up close to the wells.
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Reservoir Characterization—Recent Advances
Optimum reservoir recovery and profitability result from guidance by an effective reservoir management plan. Success in developing the most appropriate reservoir management plan requires knowledge and consideration of (1) the reservoir system, including rocks, fluids, and rock-fluid interactions, as well as wellbores and associated equipment and surface facilities; (2) the technologies available to describe, analyze, and exploit the reservoir; and (3) the business environment under which the plan will be developed and implemented. Reservoir management plans de-optimize with time as technology and the business environment change or as new reservoir information becomes available. Reservoir characterization is the process of creating an interdisciplinary high-resolution geoscience model that incorporates, integrates, and reconciles various types of geological and engineering information from pore to basin scale. The reservoir data are then conceptually and quantitatively modeled and compared to the historical production data and fluid flow distribution patterns within and beyond the limits of the reservoir to match well production histories and predict their behavior. The goals of reservoir characterization are to simultaneously (1) maintain high displacement efficiency, (2) optimize high sweep efficiency, (3) provide reliable reservoir performance predictions, and (4) reduce risk and maximize profits. Notice that in addition to the technical concepts that we normally associate with "characterization," maximizing profits is an essential element of this process. Papers from the Fourth International Reservoir Characterization Technical Conference (1997), sponsored by the U.S. Department of Energy, this publication is a unique compilation of 27 papers covering every aspect of reservoir characterization and has been a popular AAPG publication since that time. Using an interdisciplinary approach, the papers address qualitative information as well as integrated quantified data and culminate in a fully integrated study.