Klinkenberg (or slip) effect

The Klinkenberg effect is a gas flow phenomenon and occurs if the mean free path is of the same magnitude as the pore diameter. Gas then no longer “sticks” to the walls of the pore channels but slips along them. The mean free path of Brownian motion depends on pressure, temperature and the type of gas. It decreases with increasing pressure. According to Klinkenberg (1941) the apparent permeability (falsified by the slip effect) ka is a function of the true permeability k0, the mean, absolute gas pressure within the specimen p and a the Klinkenberg factor bk:

ka = k0*(1 + bk/p)

Plotting ka vs. 1/p gives bk as the gradient of the regression line of the individual data points and k0 as the intersection point of this regression line with the ordinate at 1/p = 0 bar-1. The Klinkenberg effect increases with decreasing permeability, decreasing gas pressure and decreasing gas viscosity. For practical considerations it can be assumed that the Klinkenberg effect plays an important role for k < 0.1µm2. In case of sandstone and dolomite the Klinkenberg factor bk can be assumed to follow the empirical relation:

bk = 4.84*10-3ka-0.35 (Häfner et al. 2009).

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05.05.2025 · DGMK Spring conference 2025

DGMK/ÖGEW spring conference 2025 goes on tour and we are part of it!

Meet us on booth 2, we look forward to a lively exchange in Papenburg.

 

03.10.2024 · Project HENRI

Gesteinslabor Dr. Eberhard Jahns is project and research partner within the HENRI (Hydrogen Energy Reservoir) project.

Main focus of us is the impact of H2 on the cap rock. Besides other parameters, we determine the capillary threshold pressure with different gases and gas mixtures.

First preliminary results could be presented at the 2nd HENRI conference.

 

28.07.2023 · Find us in EEK

Recently, the article "Determination of capillary threshold pressure with hydrogen gas" was published in the journal EEK.
Article from the journal EEK 01/2023

01.12.2022 · 

Gesteinslabor has successfully completed the development of a new test rig to determine the capillary threshold pressure with hydrogen.