Specimen assembly and test method for radial permeability test of ultra-low permeability rock

Abstract

A sample component and test method for radial permeability test of rock having extra-low permeability. The sample component comprises a cylindrical rock sample (3), and an upper adapter substitute (1) and a lower adapter substitute (2) both having a cylindrical main body structure. A cylindrical hole for providing a radial penetration channel for a permeable medium is processed at the center of the rock sample (3). A cylindrical boss (1-1) which is embedded and in fit with the cylindrical hole of the rock sample (3) is designed at the center of the bottom surface of the upper adapter substitute (1). A cylindrical convex ring (2-1) which is embedded and in fit with the cylindrical hole of the rock sample (3) is designed at the center of the top surface of the lower adapter substitute (2); a mounting hole (2-2) in fit with a lower pressing head is designed at the center of the bottom surface of the lower adapter substitute; and a permeable medium circulation hole penetrating the cylindrical convex ring (2-1) of the top surface from the mounting hole (2-2) is processed at the center of the lower adapter substitute. The sample component and the method can simply and effectively obtain the indoor permeability, especially the radial permeability, of the rock having extra-low permeability.

Description

technical field [0001] The invention belongs to the field of rock mechanical performance testing, in particular to a rock permeability testing method. Background technique [0002] Permeability is an important characterization parameter describing the ability of fluid to flow in porous media materials such as rocks. It has a wide range of applications in many fields such as energy extraction and storage, waste disposal, hydraulic engineering, and environmental engineering. At present, indoor permeability test methods (such as: steady state method, transient method, pore pressure oscillation method, etc.) generally use cylindrical solid samples, and the penetration medium penetrates from one end face of the sample to the other end face, using formula (1) Calculate the axial permeability of the rock. [0003] [0004] In the formula, L is the height of the cylindrical sample (m), and A is the cross-sectional area of ​​the sample (m 2 ). [0005] In recent years, with the...

AI Technical Summary

Problems solved by technology

However, this kind of engineering activities all face a common problem, that is, the permeability of rock is extremely low.

Because the ability of this kind of ultra-low permeability rock to allow fluid to pass through itself is very weak, when using the conventional experimental method to test the permeability, it will face the problems of large time span and long time-consuming experimental measurement process, and because the system flow is very small, it is difficult for the sensor The requirements are very high, and it is often difficult to achieve accurate measurement and control

Therefore, when using conventional methods to test the permeability characteristics of ultra-low permeability rocks, it will often bring large errors and difficulties to the experiment, and it is even impossible to measure the permeability characteristics of rocks.

If the efficiency of permeability testing is improved by shortening the height of the sample and increasing the cross-sectional area of ​​the sample, the sample will become a plate-like structure, which makes it difficult to couple with the stress level. Penetration testing efficiency is not significant

On the other hand, many seepage problems in engineering practice are three-dimensional diffusion flow processes, and it is difficult to describe the seepage characteristics only by examining the permeability in the axial direction of the core.

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