Low permeability rock gas permeation test device and method under air and heat coupling effect

Abstract

The invention belongs to the field of deep oil and gas exploitation rock mechanical testing, and particularly relates to a low permeability rock gas permeation test device and method under air and heat coupling effect. The test device comprises a triaxial pressure chamber, a high-pressure tank, a low-pressure tank, a confining pressure loader, an axial pressure loader, a temperature heater and a data transmission and acquisition processor; the high-pressure tank, the low-pressure tank, the confining pressure loader and the axial pressure loader are respectively connected with the triaxial pressure chamber, so as to realize gas pressure application and loading of different stress ways and different stress paths; the temperature heater is clung to the triaxial pressure chamber and seamlessly surrounds the triaxial pressure chamber, so as to realize test temperature control; the data transmission and acquisition processor is connected with the triaxial pressure chamber, the high-pressure tank, the low-pressure tank, the confining pressure loader, the axial pressure loader and the temperature heater respectively, acquires test data periodically, and stores and processes the data. The test device and method have the beneficial effect of realizing low permeability rock gas permeability tests with different temperatures and different stress loading paths.

Description

technical field [0001] The invention belongs to the field of rock mechanics testing in deep oil and gas exploitation, and in particular relates to a low-permeability rock gas permeability test device and test method under the action of gas-thermal coupling, which is suitable for the development of oil and gas fields under the action of deep high temperature and high pressure and nuclear testing under the action of gas-thermal coupling. Research and determination of gas permeability coefficient of low-permeability rock materials in waste underground storage engineering. Background technique [0002] Temperature, stress, and gas permeability are the main factors affecting the geological environment of low-permeability oil and gas reservoirs. The three are interrelated, affect each other, and restrict each other, forming a rock-gas thermal multi-field coupling problem. As a common complex medium in western oil and nuclear waste storage projects, low-permeability tight rocks wi...

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Problems solved by technology

[0004] Pan Weiyi and Lun Zengmin et al. provided a device and method for rock gas permeability measurement under high pressure in the patent "A device and method for gas permeability measurement of rock under high pressure" (application number 201010520289.1); but this device only considers Without the effect of confining pressure, it is impossible to simulate the state of unequal three-dimensional stress in the actual formation and study the influence of different axial stresses on rock gas permeability

The permeability of rock is closely related to the load. The patent applicant and Xu Weiya et al. wrote "Experimental Research on the Rheological Properties and Seepage Evolution Mechanism of Clastic Rock under the Coupling Action of Seepage-Stress" (Journal of Rock Mechanics and Engineering, 33(8): 1613- 1625, 2014.), it is believed that loading will cause rock permeability to change by 2-5 orders of magnitude, and it has strong directionality; in addition, this device calculates the rock gas permeability coefficient based on Darcy's law; but due to the deep rock density Higher permeability, lower permeability, fine channels for the flow of oil, gas and water, and greater seepage resistance, resulting in significant liquid-solid interface interaction force, and obvious start-up pressure for infiltration, resulting in the inapplicability of the classic Darcy linear seepage relationship. Therefore, this device is not suitable for gas permeability testing of deep low-permeability rocks;

[0005] Chen Yifeng and Hu Shaohua proposed a low-permeability rock transient pressure pulse permeability measurement device and measurement method in the patent "Low-permeability Rock Transient Pressure Pulse Permeability Measurement Device and Measurement Method" (application number 201310207056.X). The pressure pulse method tests the gas permeability of low-permeability rocks, but does not consider the influence of the actual three-dimensional stress state of the formation and the influence of temperature on the gas permeability characteristics of rocks. Rock gas permeability tests are also not applicable;

[0006] Xu Weiya and Wang Wei et al. proposed in the patent "A Device and Method for Measuring Rock Gas Permeability" (Application No. 201210590766.0) to calculate the rock gas permeability by recording the axial pressure difference between the two ends of the rock sample material at different times. Device and method, the calculation method of this device is similar to the pressure pulse method, but it still does not consider the influence of the state of the actual formation three-dimensional stress and temperature on the rock gas permeability characteristics; in oil and gas reservoir engineering, the formation temperature increases with the burial depth temperature increases, the thermal expansion of rock skeleton particles, the deterioration of mechanical properties, combined with the effect of gas permeation, the structure will be obviously damaged, and it is easy to expand or even disintegrate, resulting in the collapse of the pore structure of tight rock reservoirs and a significant decrease in strength. The effect of temperature is an important factor to be considered in the study of rock gas permeability

[0007] On the basis of referring to relevant domestic materials, it is considered that the original rock gas permeability testing technology has certain limitations, such as failure to consider different stress paths, uncontrollable temperature, poor sealing of test devices, and complete manual data processing; The inventor combined the multi-field coupling rock testing technology with gas permeability measurement technology and data processing and visualization technology to invent a low-permeability rock gas permeability testing device and testing method under the coupling of gas and heat. The device has high accuracy , can accurately set environmental parameters such as stress, temperature and air seepage pressure, realize data transmission and automatic processing, and output data and curves at the same time, improve the efficiency of data collection and processing, and ensure the accuracy. This technology is the first at home and abroad , with good practicality and forward-looking

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