Fluides complexes

The activity related to control and management of complex fluids at the micronic scale will be largely linked to the EOR project where the team aims at developing effective chemical formulations. In water-wet rocks, the characteristics of the pushing fluid required for an enhancement of the oil recovery are clearly established : the fluid has to be more viscous than the oil to avoid sweeping instability and ultra low interfacial tension with the oil phase is required to effectively displace oil trapped in porous media. Surfactant formulation for ultra low interfacial tension is then based on a well established microemulsion phase behavior. An original high throughput workflow has been designed to screen surfactant formulations. Solutions involving polymers to improve sweep efficiency do already exist but they fail at high temperature and in highly salted media. Moreover, polymers are very often damaged by the high shear rate they bared during the injection process. An original part of our project is to investigate viscoelastic solutions of surfactants instead of regular polymer solutions. The formulation, characterization and the study of the flow of these systems in porous media are of huge interest for the Rhodia team involved in the EOR project. At the academic level, this point raises the question of the flow of complex fluids in confined geometries. We plan to address this question by using microfluidic tools. The originality of our work will rely in the study of dynamical heterogeneities under shear flow, non local rheology, finite size effects, and on the role of the boundaries conditions on the flow. In heterogeneous oil-wet rocks, no clear roadmap exists at this stage that could allow formulating fluids able to enhance oil recovery. We plan to take advantage of our capability to model porous media in microfluidic devices to orient possible technical solutions and understand the role of viscosity contrast, surface tension, and complex fluids with normal forces. We will also focus on an important academic question : how does a meniscus between oil-water and a solid or a triple line advance at ultra low capillary numbers ? The capillary numbers involved in the industrial process are lower than 10-6 and in this range of capillary number ; no clear theoretical framework exists today to describe the wetting process.