Device for measuring permeability of ultra-low permeability rocks under action of triaxial stress

Abstract

The invention discloses a device for measuring the permeability of ultra-low permeability rocks under the action of triaxial stress, relating to the field of rock mechanics testing in the geotechnical engineering technique. The device comprises a data acquisition and processing system and a triaxial pressure system, wherein the triaxial pressure system comprises a confining pressure chamber, an axial pressure chamber, a testing chamber, a confining pressure closed loop servo metering pump, an axial pressure closed loop servo metering pump and an osmotic pressure closed loop servo metering pump; an axial pressure chamber cylinder barrel is connected to the upper end of a confining pressure chamber cylinder barrel and is fixedly sealed and connected with the confining pressure chamber cylinder barrel into a whole by bolts; the data acquisition and processing system is arranged outside the triaxial pressure system and is connected on the triaxial pressure system by the confining pressure closed loop servo metering pump, the axial pressure closed loop servo metering pump and the osmotic pressure closed loop servo metering pump respectively. The device overcomes the defects that the prior art has poor measurement accuracy, can only provide confining pressure and can not really simulate the stress state of the deep rock mass under the action of triaxial stress.

Description

technical field [0001] The invention relates to the field of rock mechanics testing in geotechnical engineering technology, more specifically to a device for measuring ultra-low permeability rock permeability under the action of triaxial stress. Background technique [0002] Permeability is one of the important physical parameters of rocks, and it is especially important for understanding the physical characteristics of deep rock masses stored in unconventional oil and gas fields and nuclear waste. With the exploitation of shale gas and tight sandstone oil and gas in recent years, there is an urgent need to A device for measuring the permeability of ultra-low-permeable rock mass under triaxial stress state, which poses a big challenge to the current experimental principles and experimental instruments. [0003] At present, most of the experimental instruments for measuring rock permeability adopt the principle of steady state method or pressure pulse method. For ultra-low pe...

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Problems solved by technology

[0003] At present, most of the experimental instruments for measuring rock permeability adopt the principle of steady state method or pressure pulse method. For ultra-low permeability rock mass in unconventional oil and gas field reservoirs, this test method has the disadvantages of backward measurement principle and poor measurement accuracy. , so it is not applicable to the measurement of the permeability of this ultra-low permeability rock mass; the more popular method for measuring the permeability of ultra-low permeability rock is the pressure oscillation method. Wave, the corresponding seepage pressure wave is measured downstream, and the ultra-low permeability rock permeability is obtained by comparing the waveforms between the two

[0004] At present, there are some shortcomings in a small number of domestic instruments that use the pressure oscillation method to measure the permeability of ultra-low permeability rock mass; The pressure oscillation method is used to measure the permeability of ultra-low permeability rocks, but this device can only provide confining pressure, not the test state of triaxial stress, and cannot truly simulate the stress state of deep rock mass under triaxial stress

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