Method for Determining Cementation Index of Heterogeneous Carbonate Reservoir

Abstract

The invention discloses a method for determining a heterogeneous carbonate reservoir cementation index. The method comprises the steps of selecting a plurality of core samples of a target reservoir; obtaining a corresponding relation between a cementation index of each core sample and irreducible water saturation; obtaining the irreducible water saturation of a core to be tested; according to the irreducible water saturation of the core to be tested, and the cementation index of the core to be tested is calculated on the basis of the corresponding relation.

Description

technical field [0001] The invention relates to the technical field of well logging evaluation of oil and gas reservoirs, in particular to a method for determining the cementation index of heterogeneous carbonate rock reservoirs. Background technique [0002] The conductivity of reservoir rock mainly depends on the fluid properties, saturation state and its spatial distribution in the pore space. For heterogeneous carbonate reservoirs, the pore structure has a significant impact on the resistivity, and sometimes fractures and caves have a great influence on the electrical conductivity. The influence of resistivity far exceeds the influence of oil and gas. Many researchers have tried to get rid of the traditional method of calculating saturation by relying solely on resistivity curves for more than 70 years, and tried to use various non-electric logging methods to calculate saturation of carbonate rocks. The effect is not ideal. Therefore, so far, the calculation of saturati...

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Problems solved by technology

The general relational formula solves the problem of accurate quantitative calculation of the saturation of heterogeneous complex reservoirs theoretically, but under the current technical conditions, two key technical The relational expression is a general solution equation, which is inconvenient to be directly used in programming calculations. That is, under the existing logging technology conditions, it is quite difficult to determine all the parameters in the general relational relation. Therefore, in practical applications, it is necessary to select according to the actual reservoir characteristics to meet the accuracy requirements. The shortest form (also known as the best form); secondly, it is necessary to choose a reliable method to accurately determine each undetermined parameter in the best form, so that the final calculation model can reflect the relationship between reservoir resistivity and water saturation to the greatest extent. real law between

For sandstone reservoirs with good physical properties and weak heterogeneity, conventional methods can achieve good application results. However, for reservoirs with complex pore structures and strong heterogeneity, simple fitting methods can only obtain this The average value of the cementation index m in the area, and the value of the cementation index m in the target layer cannot be obtained accurately

[0006] Due to the complex geological conditions of marine carbonate oil and gas in my country, formed in multi-cycle superimposed basins, the geological age is old, the evolution history is long, and the later transformation is intense, resulting in many types of carbonate reservoirs and strong heterogeneity. Using the average value of the cementation index m in a region cannot accurately calculate the oil and gas saturation of each interval reservoir

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