Method for determining stratum water saturation

Abstract

The invention relates to petroleum well-logging technology, in particular to a method for determining stratum water saturation. The method comprises the following steps: selecting a serial core of geologic feature; obtaining porosity Phi of the core and saturated core stratum water specific resistance Rw; and solving and substituting cementation index m(Rw, Phi) and saturation index n(Rw, Phi) ina common Archie water saturation computation model to calculate accurate stratum water saturation Sw. The method realizes corresponding change along with different physical properties of reservoir stratums and changes in stratum water specific resistance to ensure more accurate and reliable results, thereby having better application effect.

Description

technical field [0001] The invention relates to petroleum logging technology, in particular to a method for determining the water saturation of formations. Background technique [0002] Accurate calculation of formation water saturation is the basis of logging formation evaluation. The most classic and commonly used method to determine formation water saturation in formation evaluation is the Archie water saturation calculation model method. This method later derived some other logging evaluation methods, and these methods were also developed on the basis of Archie's water saturation calculation model. The classic Archie water saturation interpretation model is established on the basis of pure sandstone lithoelectric experiments under the condition of high salinity solution, which is the theoretical basis for quantitative interpretation of logging data. [0003] The classic Archie formation water saturation formula is: S w = ...

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Problems solved by technology

[0006] After analyzing the results of a large number of core rock electrical experiments, it is found that the values ​​of rock electrical parameters a, b, m, and n change correspondingly with the different physical properties of the reservoir and the resistivity of the contained formation water, especially for low For reservoirs with low porosity and low permeability, the values ​​of a and b change slightly, but the values ​​of m and n change greatly; while the classical Archie water saturation interpretation model calculates and solves formation water saturation, the values ​​of formation parameters m and n It is relatively fixed in a certain interval, and the values ​​of m and n do not immediately change correspondingly with the different physical properties of the reservoir and the change of formation water resistivity. Therefore, for reservoirs with large changes in physical properties and formation water resistivity, Applying the classic Archie's water saturation interpretation model to calculate the reservoir water saturation will produce large errors

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