Acquisition method of brittleness index of rock and rock brittleness evaluation method

An acquisition method and technology of rock brittleness, applied in the field of rock brittleness index acquisition, can solve the problem of not representing the quantitative characteristics of rock brittleness

Active Publication Date: 2017-06-20
CHENGDU UNIVERSITY OF TECHNOLOGY
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Problems solved by technology

[0010] The above brittleness evaluation methods establish rock brittleness evaluation methods from the aspects of elastic strain, peak strength, residual strength, elastic characteristics, etc., but these brittleness index models reflect a certain aspect of rock brittleness, and cannot represent the real brittleness of rock. feature

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  • Acquisition method of brittleness index of rock and rock brittleness evaluation method

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Embodiment

[0044] Experimental object: Taking the shale gas reservoir of Xuwu Formation in Xinchang area as an example, the strata in this section belong to the sedimentary environment of delta plain-shore shallow lake, and the lithology is mainly black, gray-black mud shale and gray, gray-brown siltstone, Fine sandstone interbedded in unequal thickness.

[0045] Experimental process: Firstly, samples of different lithologies of the target intervals in the study area were collected, and rock mechanics tests and mineral composition analyzes were carried out. The mechanical parameters needed for the brittleness index Bn can be obtained through rock mechanics tests, and the results are recorded in Table 1. The mechanical parameters mainly include compressive strength, Young's modulus, Poisson's ratio, yield strength, yield strain, and total strain. On this basis, the brittleness index B is obtained n , B n The calculation model is: B n = a·B Ym +b·B μ +c·B σ +d·B ε , in the calculati...

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Abstract

The invention discloses an acquisition method of a brittleness index of a rock and a rock brittleness evaluation method and relates to the field of brittleness evaluation of the rock. The acquisition method of the brittleness index comprises the following steps: calculating a normalized ratio of yield strain and total strain, a normalized ratio of yield strain and compressive strength, a normalized poisson ratio and a normalized Young modulus according to a resultant stress strain curve of the rock; and determining the brittleness index of the rock according to the normalized ratio of yield strain and total strain, the normalized ratio of yield strain and compressive strength, the normalized poisson ratio and the normalized Young modulus. The brittleness index comprehensively considers elastic and plastic characteristics of the rock and relatively comprehensively considers the whole process of peak-front stage stress-stain of the rock, and the required parameters are easily tested through a mechanical test. The rock brittleness evaluation method disclosed by the invention comprises the step of evaluating the brittleness of the rock by adopting the brittleness index of the rock. The evaluation method of the rock can relatively comprehensively represent the brittleness characteristic of the rock.

Description

technical field [0001] The invention relates to the field of rock brittleness evaluation, and in particular to a method for obtaining rock brittleness index and a rock brittleness evaluation method. Background technique [0002] In the development of shale (oil) gas reservoirs, one of the key technologies is to use hydraulic fracturing technology to create fractures to improve the sweeping range of production wells and the permeability of reservoirs. The brittleness characteristics of mud shale are related to its fracturing, so rock brittleness becomes an important aspect of its characteristic evaluation. [0003] The existing quantitative evaluation methods for rock brittleness mainly include the following aspects: [0004] (1) Quantitative evaluation method based on indoor rock mechanics test [0005] Indoor rock mechanics tests can obtain the failure characteristics or stress-strain characteristics of rocks, and the relevant brittleness evaluation methods are establishe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/00
CPCG01N3/00G01N2203/0075G01N2203/0087
Inventor 张昊天周文徐浩陈文玲刘鸿博
Owner CHENGDU UNIVERSITY OF TECHNOLOGY
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