Method for visually analyzing crack propagation under hydraulic fracturing effect

Abstract

The invention provides a method for visually analyzing crack propagation under hydraulic fracturing effect, comprising the steps of S1, providing a run-through crack of preset diameter along the center of a cylindrical coal sample; S2, providing a first seal mechanism and a second seal mechanism at the inner walls of the run-through crack, and constructing a space suitable for hydraulic fracturing effect; S3, placing the cylindrical coal sample with the first and second seal mechanisms as a coal sample or rock sample test piece to be tested, into an apparatus visually analyzing crack propagation under hydraulic fracturing effect, connecting a connector of a data cable for collecting parameters, and sealing and fixing; S4, setting corresponding analytic parameters in the apparatus; S5, injecting water from an inlet of a water injection pipe of the apparatus, opening a one-way valve to allow the water in a water delivery pipe to enter the space for hydraulic fracturing effect, subjecting the test piece to hydraulic fracturing effect, and processing recorded data and images after set hydraulic fracturing results are reached. Inner crack distribution characteristics and propagation images of a test piece under hydraulic fracturing effect can be acquired by using the method.

Description

technical field [0001] The invention relates to the technical field of hydraulic fracturing, in particular to a visual analysis method for crack propagation under the action of hydraulic fracturing. Background technique [0002] Hydraulic fracturing is an oil and gas stimulation measure with broad application prospects, and hydraulic fracturing technology is currently the main form of exploitation of natural gas, coalbed methane and other gases. In coal mine production, hydraulic fracturing technology can be used for hard and difficult roof control, rock burst prevention, and coalbed methane drainage enhancement. The essence of this method is to cut grooves in the borehole and inject high-pressure water to form directional cracks in the coal rock, destroy the integrity of the rock, and improve the permeability of the coal rock. However, the inventors of the present invention have found through research that the cracks produced by hydraulic fracturing often show poor control...

AI Technical Summary

Problems solved by technology

[0003] The cracks produced by hydraulic fracturing in the existing technology often show poor controllability and easy to form local stress concentration. If hydraulic fracturing technology is used more maturely in actual production, it is necessary to understand hydraulic fracturing. The law of crack growth can solve the technical problem of its poor controllability. The invention provides a visual analysis method of crack growth under the action of hydraulic fracturing

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