Petrophysical characterization of low-permeable carbonaceous rocks: Comparison of different experimental methods

Experimental Investigation of Gas Dynamic Effects Using Nanoporous Synthetic Materials as Tight Rock Analogues

“…Differences between the Klinkenberg-corrected permeability coefficients ( k ∞ ) of rocks measured with helium as compared to other gases ("helium anomaly") have been commonly observed in previous studies (Sinha et al 2013;Ghanizadeh et al 2014a, b;Gensterblum et al 2014;Fink et al 2017a;Shabani et al 2020). Permeability coefficients measured with helium can be several times higher than those measured with other gases (Fig.…”

“…Therefore, rapid temperature fluctuations within the gas stream, by, e.g., the Joule-Thomson effect, could not be detected. A decrease in temperature can lead to phase changes and the formation of immobile liquid films that can affect permeability Gas shales (Sinha et al, 2013) Alum shale (Ghanizadeh et al, 2014a) Posidonia shale (Ghanizadeh et al, 2014b) Bossier shale (Fink et al, 2017a) Kimmeridge clay (Gaus, 2020) Eagle Ford shale (Gaus, 2020) Iranian carbonates (Shabani et al, 2020) Ceramic disk (present study) k ∞ (He) = 0.002 µD k ∞ (He) / k ∞ (CH 4 ) = 63…”

“…Generally, the difference between permeability coefficients measured with helium and other gases tends to increase with decreasing permeability. This holds true for shales with the exception of carbonate-rich samples from Iran (Shabani et al 2020). This effect is probably controlled by a complex interaction of multiple rock-and fluidspecific properties, such as rock composition, pore/matrix structure (e.g., pore size, fracture, cleats, cementation), mechanical stress behavior (e.g., rigid framework or creep effects), maturation, fluid type (e.g., sorbing gas, polarizability) and sorption/swelling effects (e.g., or organic matter and/or clay).…”

“…The gas slip factor, a measure of the average transport pore size, determined with helium is 3.47 MPa and thus well within the range of values for shales reported in other studies. Slip factors range mostly from 1.5 to 6 MPa with the highest published value of 8.6 MPa (Heller et al 2014;Ghanizadeh et al 2014a, b;Fink et al 2017aFink et al , 2018Letham and Bustin 2018;Gaus et al 2019;Nolte et al 2019;Shabani et al 2020). Of course, the results obtained with this "ideal" system should only be applied to natural tight rock systems that have similar transport properties.…”