Foam injection during oil production or ground remediation is aimed at overcoming problems of gravity segregation and viscous fingeringa created by fluid injection. Improving this practice requires knowledge of the detailed structure of a foam flowing in a real porous medium. A multi-scale approach using complementary characterization techniques, in terms of resolution (space and time) and field of viewb, made it possible to access this information in situ, by combining conventional petrophysical measurement equipment with different observation cells.
On a core scale, the X-ray scanner is used to quantitatively monitor local fluid saturations (gas or liquid) with a time resolution of a few seconds(1). On a smaller scale, the combination of spatial (1 μm) and temporal (1 s) resolutions provided by synchrotron X-ray microtomography gave access for the very first time to in situ 3D images of the structure of a foam trapped in a porous medium (figure a). The analysis of volumes over time highlighted the intermittent nature of the trapping(2).
Measurements on foam bubble and lamellae scales were conducted via SANSc using different contrasts. They provided information concerning the saturation of the medium by the fluids in place and S/V, the quantity of gas/liquid interfaces by unit of volume (figure b).
(b) SANS micro-macro correlation for different foam qualities (fg) e.
Using this information on scattering objects, established on several scales, it was possible to describe transport mechanisms as well as the size of oil micro-droplets(3). These measurements also make it possible to estimate the average size of bubbles for different foam qualities and different porous media.
a - Due to the low density and viscosity of the gas compared to the liquid
b - Solid angle seen by the sensor
c - Small angle neutron scattering
d - Each color corresponds to a bubble, separated by image analysis
e - Foam quality, defined as the ratio of the gas volumetric flow rate to the total volumetric flow (liquid + gas)
(1) C. Ouali, E. Rosenberg, L. Barré, B. Bourbiaux, Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles, 74 (2019) 33.
https://doi.org/10.2516/ogst/2019005
(2) R. Poryles, N. Gland, A. King, E. Rosenberg, L. Barré, T. Chevalier, Soft Matter, 2020,16, 6354-6361.
https://doi.org/10.1039/D0SM00392A
(3) R. Poryles, T. Chevalier, N. Gland, E. Rosenberg, L. Barré, Soft Matter, 2020, 16, 1771-1778.
https://doi.org/10.1039/C9SM01936G
Scientific contact: Thibaud Chevalier