Extracting Maximum Petrophysical and Geological Information from a Limited Reservoir Database
Maqsood Ali, Adwait Chawathé, Ahmed Ouenes, Martha Cather, William Weiss, 1999. "Extracting Maximum Petrophysical and Geological Information from a Limited Reservoir Database", Reservoir Characterization—Recent Advances, Richard A. Schatzinger, John F. Jordan
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The characterization of old fields lacking sufficient core and log data is a challenging task. This paper describes a methodology that uses both new and conventional tools to build a reliable reservoir model for the Sulimar Queen field. At the fine scale, permeability measured on a fine grid with a minipermeameter was used in conjunction with the pétrographie data collected on multiple thin sections. The use of regression analysis and a newly developed fuzzy logic algorithm led to the identification of key pétrographie elements that control permeability. At the log scale, old gamma ray logs were first rescaled/calibrated throughout the entire field for consistency and reliability using only four modern logs. Using data from one cored well and the rescaled gamma ray logs, correlations among core porosity, permeability, total water content, and gamma ray were developed to complete the small-scale characterization. At the reservoir scale, outcrop data and the rescaled gamma logs were used to define the reservoir structure over an area of 10 mi2 (26 km2) where only 36 wells were available. Given the structure, the rescaled gamma ray logs were used to build the reservoir volume by identifying the flow units and their continuity. Finally, history-matching results constrained to the primary production were used to estimate the dynamic reservoir properties, such as relative permeabilities, to complete the characterization. The obtained reservoir model was tested by forecasting the waterflood performance and was in good agreement with the actual performance.
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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.