A shale gas formation lithology identification method, system, storage medium, and terminal

Abstract

The invention belongs to the technical field of unconventional reservoir lithology identification, and discloses a shale gas formation lithology identification method, system, storage medium, and terminal. Firstly, based on tests such as major and trace elements, whole rock analysis, and organic carbon, a biological The discriminant criteria for genetic siliceous shale, considering the particle size, mineral composition, and siliceous source, classifies the lithology of shale gas formations, and counts the responses of logging curves of different lithologies; The Ma curve establishes different lithology discrimination standards, and finally uses the well logging curve to realize the fine identification of different lithologies in shale gas formations. The well logging curve has a high vertical resolution and can continuously describe the vertical distribution of different types of shale, which can effectively make up for the shortcomings of limited core test data, long test period, and inability to continuously describe the lithology distribution of shale. Gas and geological sweet spots are preferred for reference. The invention can improve the efficiency and precision of lithology identification.

Description

technical field [0001] The invention belongs to the technical field of unconventional reservoir lithology interpretation, and in particular relates to a shale gas formation lithology identification method, system, storage medium and terminal. Background technique [0002] At present, fine interpretation of lithology is the basis for evaluating reservoir parameters of oil and gas reservoirs, especially for unconventional oil and gas reservoirs such as shale oil and gas, where lithology frequently changes interactively, and the accuracy of lithology identification determines reservoir evaluation and geological "sweet spots" Preferred reliability. At present, there are usually two methods for lithology identification. One is the intuitive method, that is, to observe the core or cuttings downhole with the naked eye, and determine the lithology according to the color, particle size, sorting, etc. This method is more effective for conventional clastic rocks. In shale formations w...

AI Technical Summary

Problems solved by technology

Fine logging lithology interpretation is very limited and widely used in conventional clastic rock formations, but it faces the following problems in shale gas formations: 1) The shale grain size as a whole belongs to mud level, if the lithology division scheme of conventional clastic rocks is adopted (Usually divided into conglomerate, coarse sandstone, medium sandstone, fine siltstone and mudstone according to grain size) can only be interpreted as one type of lithology, which needs to be further subdivided according to mineral composition and organic matter abundance, so as to adapt to the evaluation of shale gas sweet spots However, the lithology fine division scheme of shale gas formations is not yet clear; 2) Geological characteristics such as fine grain size, complex mineral composition, low porosity, rich in organic matter, etc., lead to the variation of log curve response values ​​of shale formations with different lithologies. Small, the curve intersection chart suitable for distinguishing the lithology of conventional clastic rocks is difficult to apply to shale gas formations, and it is necessary to establish a fine logging lithology identification method suitable for shale gas formations according to the subdivision scheme of gas-bearing shale lithology

[0004] To sum up, the problems existing in the existing technology are: (1) The overall lithology of shale gas formations is relatively fine, so it is necessary to establish a shale lithology subdivision scheme based on the abundance of minerals and organic matter. Rock and gas geological sweet spot evaluation, simultaneous logging can distinguish

[0005] (2) Shale mineral composition is complex and variable, low porosity, rich in organic matter and other characteristics different from conventional clastic rock formations, which makes it difficult to apply conventional shale gas formation lithology identification methods, and it is urgent to focus on shale lithology development characteristics, Establish a set of logging identification standards and procedures

[0006] (3) It is the most accurate method to determine shale lithology by using core test data, but shale coring is limited and the experiment period is long, so the vertical distribution cannot be continuously described. Logging lithology identification can effectively make up for the deficiency of core analysis

At the same time, shale gas reservoirs are dominated by fine-grained deposits, diverse material compositions, low porosity, and rich in organic matter, etc., which will weaken the difference in response of logging curves of different lithologies and increase the error of logging lithology identification

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