A method and device for testing energy change and permeability of nitrogen-induced fracturing coal seams

Abstract

The invention relates to a method and a device for testing the energy change and the permeability of a nitrogen fracturing coal seam. The device comprises a reservoir environment simulation system, a power fracturing system, a data display system and a testing system, wherein the reservoir environment simulation system comprises an axial stress loading system and a confining pressure loading system; the reservoir environment simulation system can be used for truly simulating the stress state of the coal seam; the power fracturing system can be used for pumping gas into the testing system so as to fracture coal samples; the testing system comprises a plurality of coal sample tanks, and the plurality of coal sample tanks are selected to be connected or closed according to the situation, so that the plurality of coal samples can be tested; the method comprises the steps of detecting the air tightness, arranging the coal samples, connecting and fixing the device, carrying out reservoir environment simulation, fracturing by gas injection and testing. The method and the device not only are capable of testing the energy change and the permeability of the reservoir of a single coal body, but also are capable of testing the energy change and the permeability of the reservoir under the condition that different coal bodies are combined; the method and the device are high in test flexibility and accuracy rate.

Description

technical field [0001] The invention belongs to the technical field of coal seam energy change and permeability testing, and in particular relates to a method and device for testing energy change and permeability of coal seam cracking by nitrogen gas. Background technique [0002] my country has abundant coalbed methane resources, according to the latest statistics, its volume is 36.81 trillion m 3 , ranking third in the world. Rational development and utilization of these rich coalbed methane resources can effectively prevent coal and gas outbursts on the one hand, and can be used as energy on the other hand, and can reduce greenhouse gas emissions at the same time. [0003] After more than 30 years of exploration and development of surface coalbed methane in my country, the national surface coalbed methane production in 2013 was only 3 billion m 3 , the underground extraction volume is 12.6 billion m 3 , There is a huge contrast between the abundant resources and the ac...

AI Technical Summary

Problems solved by technology

[0006] In the prior art, the change of permeability is tested by generating endogenous fractures and exogenous fractures respectively. The exogenous fractures are generated by the combination of gas and water, and the effect of a single gas cannot be tested, and it can only Test a single coal sample. When multiple coal samples need to be tested and compared, it is necessary to take out the previous coal sample and test again

[0007] However, for coal reservoirs with well-developed fractures and high pressure, how much the energy of the reservoir can be increased after nitrogen injection, and how much the conductivity of the coal seam can be increased, it is currently impossible to give a definite answer

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