PERMEABILITY AND DIFFUSION COEFFICIENT PREDICTION OF FRACTAL POROUS MEDIA WITH NANOSCALE PORES FOR GAS TRANSPORT

Understanding gas transport behavior though fractured porous media is essential in many fields including fiber science, energy science, soil science, environmental engineering, chemical engineering, etc. In this paper, a fractal model is developed to characterize gas diffusion through fractured porous media, where a bundle of fractal-like tree branching networks is used to represent the fracture system according to fractal scaling laws. The analytical expression for relative gas diffusion coefficient of fractured porous media is derived. The proposed fractal model has been validated by the available experimental data and empirical correlations. From the parametrical study, it can be seen that structural parameters of fractured porous media (for example porosity, the fractal dimension, the diameter ratio, the length ratio and the branching angle) have a significant effect on equivalent gas transport properties. Gas relative diffusion coefficient has a positive correlation with the porosity, the pore size fractal dimension, or the diameter ratio, whereas it has a negative correlation with the length ratio, the branching levels, or the branching angle. The proposed fractal model does not only shed light on gas transport physics of fractured porous media, but also reveals more mechanisms than experimental measurements.

Download Full-text

Velocity and diffusion coefficient of a random asymmetric one-dimensional hopping model

Journal de Physique ◽

10.1051/jphys:01989005008089900 ◽

1989 ◽

Vol 50 (8) ◽

pp. 899-921 ◽

Cited By ~ 23

Author(s):

C. Aslangul ◽

N. Pottier ◽

D. Saint-James

Keyword(s):

Diffusion Coefficient ◽

One Dimensional ◽

And Diffusion ◽

Hopping Model

Download Full-text

Experimental study of the supercritical CO 2 diffusion coefficient in porous media under reservoir conditions

Royal Society Open Science ◽

10.1098/rsos.181902 ◽

2019 ◽

Vol 6 (6) ◽

pp. 181902 ◽

Cited By ~ 1

Author(s):

Junchen Lv ◽

Yuan Chi ◽

Changzhong Zhao ◽

Yi Zhang ◽

Hailin Mu

Keyword(s):

Porous Media ◽

Diffusion Coefficient ◽

Oil Recovery ◽

Carbon Capture ◽

Carbon Capture And Storage ◽

Elevated Pressure ◽

Experimental Results ◽

Saturated Porous Media ◽

Reservoir Conditions ◽

The Impact

Reliable measurement of the CO 2 diffusion coefficient in consolidated oil-saturated porous media is critical for the design and performance of CO 2 -enhanced oil recovery (EOR) and carbon capture and storage (CCS) projects. A thorough experimental investigation of the supercritical CO 2 diffusion in n -decane-saturated Berea cores with permeabilities of 50 and 100 mD was conducted in this study at elevated pressure (10–25 MPa) and temperature (333.15–373.15 K), which simulated actual reservoir conditions. The supercritical CO 2 diffusion coefficients in the Berea cores were calculated by a model appropriate for diffusion in porous media based on Fick's Law. The results show that the supercritical CO 2 diffusion coefficient increases as the pressure, temperature and permeability increase. The supercritical CO 2 diffusion coefficient first increases slowly at 10 MPa and then grows significantly with increasing pressure. The impact of the pressure decreases at elevated temperature. The effect of permeability remains steady despite the temperature change during the experiments. The effect of gas state and porous media on the supercritical CO 2 diffusion coefficient was further discussed by comparing the results of this study with previous study. Based on the experimental results, an empirical correlation for supercritical CO 2 diffusion coefficient in n -decane-saturated porous media was developed. The experimental results contribute to the study of supercritical CO 2 diffusion in compact porous media.

Download Full-text