In-situ shale brittleness test device and method based on acoustic emission technique

Abstract

The invention provides an in-situ shale brittleness test device and method based on an acoustic emission technique. The device comprises a triaxial pressure kettle which can bear different confining pressures, a base used for fixing a core, an acoustic emission sensor arranged in the base, a temperature sensor installed on the base, strain gauges stuck in the different directions of the core, an electromagnetic heating coil wrapping the exterior of the triaxial pressure kettle and corresponding line channels. The test method comprises the steps that acoustic emission accumulation energy and stress-strain synchronous data of in-situ shale are obtained through the test device, and then the brittleness index of the in-situ shale is determined according to a built relation model of the acoustic emission accumulation energy, the stress-strain and the brittleness index of the in-situ shale. The in-situ shale brittleness test device and method based on the acoustic emission technique get rid of restriction of a large triaxial compressor and limitation of external arrangement of the acoustic emission sensor, an acoustic emission accumulation energy value and a stress-strain value can be synchronously obtained, and the in-situ shale brittleness evaluation rationality and accuracy are improved through the determination method.

Description

technical field [0001] The invention relates to the field of rock mechanics experiments, in particular to an in-situ shale brittleness test device and method based on acoustic emission technology. Background technique [0002] Due to the tightness of shale reservoirs, which are low porosity and ultra-low permeability reservoirs, fracturing operations are required to achieve economic development, and rock brittleness, as an inherent mechanical property of rocks, determines the fracturing and fracturing properties of shale reservoirs. Difficulty of crack reconstruction. Therefore, the frackability of rocks is generally evaluated by the brittleness index of rocks. The higher the brittleness index, the reservoir is generally hard and brittle, sensitive to fracturing operations, and can quickly form complex network fractures. [0003] At present, the acoustic emission brittleness index measurement method is to measure the acoustic emission energy during the rock fracturing proce...

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Problems solved by technology

[0003] At present, the acoustic emission brittleness index measurement method is to measure the acoustic emission energy during the rock fracturing process. For example, the invention patent with the Chinese patent application number 201310254628. When the external factors such as speed are different, the energy of acoustic emission changes accordingly, which makes the measured brittleness index deviate

In addition, when conducting acoustic emission experiments, on the one hand, the acoustic emission sensors are often placed outside the autoclave, resulting in a serious energy loss of the acoustic emission signal; data, reducing the accuracy of determining the rock brittleness index

For example, the patent application number is 201110212775.1 and the patent application number is 201320057732.5. Although the acoustic emission sensor is placed on the base, which reduces the energy loss of the acoustic emission signal, it cannot simultaneously obtain the characteristic parameters of acoustic emission of shale under in-situ temperature and pressure. Stress-strain data

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