Shale gas formation lithology recognition method and system, storage medium and terminal

Abstract

The invention belongs to the technical field of unconventional reservoir lithology recognition, and discloses a shale gas formation lithology recognition method and system, a storage medium and a terminal. Firstly, based on tests such as main microelements, total rock analysis and organic carbon, discrimination criteria of biogenic siliceous shale are established, the granularity, mineral components and siliceous sources are considered, the shale gas formation lithology is divided, and different lithology logging curve responses are counted; and then a density-neutron standardized amplitude range is established, in combination with a natural gamma curve, different lithology discrimination criteria are established, and finally precise recognition of different kinds of lithology of a shale gas formation is achieved through a logging curve. The logging curve has high vertical distinguishability, vertical distribution of the shale of different types can be continuously depicted, the defects that core experimental data are limited, the experimental period is long, and distribution of the lithology of the shale cannot be continuously depicted can be effectively overcome, and meanwhile reference is provided for optimizing shale gas geological desserts. The efficiency and the precision of lithology recognition can be improved.

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...

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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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