Method for calculating shale content of conglomerate oil reservoir based on log curve reconstruction

Abstract

The invention provides a method for calculating the shale content of a conglomerate oil reservoir based on log curve reconstruction. The method comprises the following steps of (1), measuring the shale content of a rock core sample; (2), optimal selection of sensitivity curves of shale: determining the shale content of the conglomerate oil reservoir and a compensated neutron porosity log curve as well as a compensated density log curve as sensitivity curves for calculating the shale content; (3), normalization processing of the curves: on the basis of the sensitivity curves for calculating the shale content, which are determined in the step (2), carrying out the normalization processing on the compensated neutron porosity log curve and the compensated density log curve respectively; (4), constructing a shale content calculating parameter (NZCS (New Zealand Computing Solution)); (5), establishing and optimizing a calculation model. By using the method for calculating the shale content of the conglomerate oil reservoir based on the log curve reconstruction, which is provided by the invention, the influences of lithology and heterogeneity on a calculation result of the method in the process of calculating the shale content of the conglomerate oil reservoir are eliminated; the calculation precision of the shale content of a reservoir stratum is improved.

Description

technical field [0001] The invention belongs to the technical field of petroleum development reservoir engineering, and in particular relates to a method for calculating the shale content of conglomerate reservoirs based on logging curve reconstruction. Background technique [0002] Shale content is an important parameter in reservoir evaluation, and its accurate calculation has important guiding significance for the judgment of depositional environment, the establishment of permeability model and the study of microscopic pore structure. Conglomerate reservoirs have serious reservoir heterogeneity, complex and changeable lithology, and complex modal distribution characteristics due to the close provenance, multiple water systems, and rapidly changing depositional environment. The difficulty of quantitative evaluation of quality and content. In addition, at present, all oilfields in China have entered the tertiary oil recovery stage based on polymer flooding, and conglomerat...

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Problems solved by technology

"Calculation method of shale content in high gamma formation based on curve reconstruction" published by Sima Liqiang et al. ("Logging Technology") is based on natural gamma ray spectrum logging, using the idea of ​​curve combination to construct a new uranium-free gamma The Ma curve can effectively calculate the shale content; Hou Lianhua et al. published the "Calculation Method and Application of Shale Content in Turbidite Reservoirs" ("Journal of Petroleum University"), and found that due to radioactive minerals and formation water salinity Influenced by natural gamma ray and spontaneous potential curves cannot truly reflect the shale content of the reservoir, a method of calculating the shale content by using the corrected resistivity curve is proposed

However, the above methods have two deficiencies. One is that recent studies on conglomerate sedimentological characteristics have shown that for conglomerate reservoirs near provenance, because rock particles have not been transported, sorted and rounded over long distances, radioactive The distribution of minerals is random, and high-gamma sandstone or low-gamma mudstone often appears, and the gamma curve cannot be used as a sensitive parameter for the calculation of shale content; the second is for conglomerate oil with complex lithology and severe heterogeneity Reservoirs, the content and particle size (lithology) of clastic particles have a greater impact on the electrical properties of the reservoir than the shale content, and the resistivity of conglomerate reservoirs has a relatively large range, ranging from 15 to 700 Ω·m Among them, the main factor causing such a large difference in reservoir resistivity is conglomerate lithology rather than shale content and pore fluid properties. The resistivity curve is not sensitive to shale, and the calculation accuracy is relatively low.

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