Thesis by Anne-Sophie Esneu: « Étude des mécanismes d’endommagement des formations lors de la réinjection des fluides géothermiques » (Study of formation damage mechanisms during geothermal fluid reinjection).
Injectivity in geological formations is a well documented factor in fields related to new energies and the climate (geothermal energy, underground CO2 storage, etc.). The clogging of geological formations, a recurrent problem causing injectivity losses, is associated with the fact that reinjected water frequently carries a high concentration of suspended organic and mineral elements, in the form of colloidal particles. To attempt to overcome this clogging, or at the very least minimize it, it is important to have a clear understanding of the mechanisms at work.
Such was the aim of this PhD research conducted using a microfluidics approach (Figure 1) combining two visualization techniques: optical imaging [1] and laser-induced fluorescence [2]. It made it possible to identify different deposition sites and regimes, as well as to describe clogging mechanisms, including the identification of a shear-induced aggregation phenomenon [3]. The body of results obtained using microfluidics was validated for more real systems (for example, a suspension of polystyrene particles in reconstituted sand beds or clay particles in micromodels) and paved the way for potential solutions to the phenomenon.
(a) Illustration of the micromodel used. P1/P2/P3 and P4 correspond to pressure measurements.
(b) Example of observation based on traditional imaging of particle transport in porous media. The deposits, pore space and grains are shown in black, dark grey and light grey respectively. The scale bar corresponds to 850 µm.
(c) Characteristic evolution of the mobility reduction coefficient Rm during injection of a particulate suspension and of the associated porosity reduction, obtained via image processing.
(d) Local observations of deposition sites and nature as a function of location in the porous medium and local flow rate obtained by numerical simulation. G and PS correspond to a grain and the pore space respectively. The deposit is shown in black.
References:
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A.-S. Esneu, C. Marlière, L. Nabzar, A. Erriguible, S. Glockner, S. Marre and J. Boujlel. Transport and clogging of colloidal particles: effects of concentration and geometry of the porous medium. In Proceedings of World Geothermal Congress 2023, Beijing, China, October 2023.
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A.-S. Esneu, V. Ricordeau, A. Perez, G. Pilla, M. Bardi and J. Boujlel. The use of Laser-Induce Fluorescence Imaging to investigate transport phenomena of complex fluids in a 2D porous medium. Under review in Transport in Porous Media.
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A.-S. Esneu, A. Erriguible, S. Glockner, S. Marre and J. Boujlel. 2D heterogeneous porous medium permeability reduction by shear-induced aggregation. Submitted in Physics Review Letters.
Scientific contacts: anne-sophie.esneu@ifpen.fr and jalila.boujlel@ifpen.fr