Method for identifying argillaceous rocks under polarizing microscope

Abstract

The invention provides a method for identifying argillaceous rocks under a polarizing microscope, belonging to the technical field of rock variety identification. The method comprises the following steps: positioning directionally aligned minerals in rock slices in the center of the horizon of a crossed polarizing microscope, and enabling the directions of principal axes of the directionally aligned minerals to be parallel to a longitudinal cross hair of an eyepiece; selecting an objective lens with magnification times being 5; turning a stage to the right at an angle of 45 degrees to enable the directionally aligned minerals to be in an extinction state; inserting a gypsum test plate; judging that the directionally aligned minerals x1 towards the right have purple blue interference colors; determining the percentage content of all the directionally aligned minerals x1 towards the right with purple blue interference colors in the horizon by adopting an area visual estimation method; turning the stage to the left at an angle of 90 degrees; judging that the directionally aligned minerals x2 towards the left have orange interference colors; visually estimating the percentage content of all the directionally aligned minerals x2 towards the left with orange interference colors in the horizon. The method can provide the basis for the oil finding directions for petroleum exploration and development and discovery of new oilfields, and has practical values.

Description

Technical field: [0001] The invention relates to an identification method of argillaceous rock under a polarizing microscope, which belongs to the technical field of rock variety identification, and is a method for quickly and accurately identifying argillaceous rock with a particle size less than 0.0313 mm under a polarizing microscope. Background technique: [0002] At present, the identification method of argillaceous rock under the polarizing microscope in China is based on the People's Republic of China oil and gas industry standard SY / T5368--2000 "Identification of Rock Thin Sections". [0003] The disadvantage of this method is that it is difficult to distinguish argillaceous rocks with a particle size of less than 0.0313 mm from volcanic ash tuffs. Since countless fine clay minerals that make up argillaceous rocks and countless minerals that make up volcanic ash tuff are distributed in aggregates under a polarizing microscope, each fine mineral is in the shape of a n...

AI Technical Summary

Problems solved by technology

[0005] Argillaceous rock and volcanic ash tuff are fundamentally different rock types in nature. If the lithology is not accurately characterized, it is impossible to discuss the properties of the entire reservoir, and it is also impossible to determine the relationship between lithology, electrical properties, oil content and physical properties. Therefore, it seriously affects the direction of oil exploration and development and the discovery of new oil fields