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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/13694

Title: Water saturation computation from laboratory, 3D regression [Estimation de la saturation en eau au laboratories par regression 3D]
Authors: Hamada, G.M
Al-Awad, M.N.J.,
Alsughayer, A.A
Keywords: Computational methods; Mechanical permeability; Oil wells; Parameter estimation; Porosity; Regression analysis; Salinity measurement; Saturation (materials composition); Water
Issue Date: 2002
Publisher: Editions Technip
Citation: Oil and Gas Science and Technology, 57 (6), pp. 637-651.
Abstract: An accurate determination of initial oil in place in the early life of reservoirs or an evaluation of a developed reservoir is required to well estimate the hydrocarbon volumes. Modified Archie's formula (Sw = (a Rw/ Φm R1)l/n) is the basic equation to compute water saturation in clean formation or suitable shaly water saturation model in shaly formation. The accuracy of water saturation value for given reservoir conditions depends on the accuracy of Archie's parameters a, m and n. The terms of Archie's relationship have been subjected to many laboratory investigations and even more speculations. There are many factors affecting porosity exponent, m, saturation exponent, n and tortuosity factor, a. Therefore, it is very difficult to fix Archie's parameters and neglecting reservoir characteristics such as rock wettability, formation water salinity, permeability, porosity and fluids distribution. This paper presents a new technique to determine Archie's parameters a, m and n. The developed technique is based on the concept of three dimensional-regression (3D) plot of water saturation, formation resistivity and porosity. This 3D technique provides simultaneous values of Archie's parameters. Also, the 3D technique overcomes the uncertainty problems due to the separate use of formation resistivity factor-porosity and water saturation equations to get a, m and n parameters. Two field examples are given to show the applicability of the 3D technique in comparison with three other techniques: - common values of Archie's parameters, - conventional technique and - Core Archie-Parameter Estimation (CAPE) technique. The comparison among the four techniques has shown that 3D technique provides an accurate and physically meaningful way to get Archie's parameters a, m and n for given core samples. Water saturation profiles, using Archie's parameters obtained from the four techniques, have been obtained for the studied section in the wells. These profiles have shown a significant difference in water saturation values. This difference could be mainly attributed to the uncertainty level for Archie's parameters from each technique. The effect of saturation exponent on the accuracy of water saturation computation was tested using Archie's parameters derived from conventional technique and 3D technique in the two wells
URI: http://hdl.handle.net/123456789/13694
ISSN: 12944475
Appears in Collections:College of Engineering

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