Method for measuring water saturation of tight sandstone reservoir

Abstract

The invention discloses a method for measuring the water saturation of a tight sandstone reservoir. The method comprises the following steps of acquiring a plurality of types of logging curves of eachreservoir through known rock electricity experiments of rock cores of a plurality of reservoirs; calculating the correlation dimension of the logging curve of each category of each reservoir; solvinga first fractal dimension and a second fractal dimension of each reservoir, establishing a first linear relational expression between the first fractal dimension of each reservoir and the cementationindex of the reservoir by adopting a linear fitting method, and establishing a second linear relational expression between the second fractal dimension of each reservoir and the saturation index of the reservoir; establishing a linear relation between the cementation index of each reservoir and loga, and dividing the to-be-logged into a plurality of reservoirs; calculating the cementation index and the saturation index of each reservoir to be logged; and calculating the water saturation of each reservoir to be logged. According to the measuring method, the water saturation of the tight sandstone reservoir can be accurately measured.

Description

technical field [0001] The invention relates to the field of logging interpretation, in particular to a method for measuring the water saturation of tight sandstone reservoirs. Background technique [0002] In the evaluation of water saturation in the field of well logging interpretation, the current common method is to use Archie's formula to calculate the value of water saturation. The cementation index m and saturation index n in Archie's formula are usually fixed values ​​of m and n obtained from a well rock electrical experiment. [0003] The inventors found that for tight sandstone reservoirs, the lithology is tight, the pores are small, the throats are thin, the connectivity is poor and the heterogeneity is strong, the formation heterogeneity is strong, fractures are developed, and the pore structure is complex, clay minerals, Mineral components such as chloride salt are complex, and fractures are widely developed in the reservoir. The cementation index (m) and satur...

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Problems solved by technology

[0003] The inventors found that for tight sandstone reservoirs, the lithology is tight, the pores are small, the throats are thin, the connectivity is poor and the heterogeneity is strong, the formation heterogeneity is strong, fractures are developed, and the pore structure is complex, clay minerals, Mineral components such as chloride salt are complex, and fractures are widely developed in the reservoir. The cementation index (m) and saturation index (n) of this type of reservoir deviate from the empirical value. The value of water saturation obtained by substituting it into Archie's formula also has a large error

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