Hydrogels to unlock deep geothermal energy and lithium production in heterogeneous reservoirs

An increasing number of geothermal doublets operate fractured or heterogeneous deep reservoirs, where heat production is often combined with lithium extraction. Their long-term economic viability can be compromised by the formation of hydraulic short circuits between injection and production wells (1,2). One remediation solution, inspired by Conformance Control techniques from the oil industry (3,4), is the use of hydrogels to plug the preferential flow paths. However, the gels must be adapted to the challenges of deep geothermal, namely: high temperatures (>100 °C) and specific operational conditions (controlled water circulation from the surface). The thesis aims to deepen the understanding of the mechanisms governing the kinetics of gel formation, their mechanical properties, and their aging when subjected to complex deformations in confined environments under high temperature and high-pressure (HP/HT) conditions. The ultimate practical goal is to develop industrial systems adapted to geothermal energy and lithium production, capable of plugging target zones deep within reservoirs while remaining safe for the process and infrastructure.
The experiments will include rheology studies, structural analysis through light or neutron scattering under pressure in large facilities, long-term stability tests, and injection trials on fractured cores in a dedicated HP/HT coreflood rig. The results will enable linking chemical characteristics, rock properties, and injection conditions to gel performance. 
At the intersection of soft matter, complex fluids in porous media, and subsurface sciences, this research addresses novel questions about gels under extreme conditions. The doctoral candidate may have an initial education in one of these disciplinary fields and will acquire, during the thesis, skills in the other areas as well as scientific and experimental expertise in all the techniques used. In addition, notably through the partnerships of IFP Energies nouvelles, him/her will gain a solid understanding of the industrial ecosystem of geothermal energy and lithium production, which is rapidly developing. Furthermore, the publications and communications resulting from the thesis will provide him/her with excellent visibility both in the academic and industrial worlds.

Keywords: gels, geothermal energy, lithium, hydraulic short circuits, rheology, radiation scattering, porous media, sol-gel transition, fractured cores, Conformance Control, petrophysics.

• Academic supervisor    Dr Clémence LE CŒUR, LLB et ICMPE, ORCID : 0000-0001-5072-1066
• Doctoral School    ED 531 SIE, Université Paris-Est
• IFPEN supervisor    Dr David ROUSSEAU, ORCID : 0000-0001-8519-8447
• PhD location    IFPEN, Rueil-Malmaison, France
• Duration and start date    3 years, starting in the fourth quarter 2026 (Novembre 2)
• Employer    IFPEN
• Academic requirements    University Master's degree in Physics or Physical Chemistry
• Language requirements    English level B2 (CEFR), willingness to learn French    
• Other requirements    Interest in experimentation, knowledge in physical chemistry of materials, and, if possible, in geosciences.

To apply, please send your cover letter and CV to the IFPEN supervisor indicated here below.