Can unmixed complex forming polymer surfactant formulations be injected into oil reservoirs or aquifers without clogging them?

In the context of enhanced oil recovery or soil remediation, we study the role of interactions between polymers and surfactants on the injectivity of formulations containing mixtures of polymers and surfactants. We show that contrary to the first intuition, the formation of aggregates in polymers surfactants formulations is not necessarily a hindrance to the injection of these formulations into pores. It is important above all to compare the size of aggregates according to the applied shear rate and the pore size to find the formulations that may induce clogging. We highlight a new positive and unexpected phenomenon. The small aggregates that do not lead to clogging ensure the transport of the surfactant vesicles in the porous medium and limit the adsorption of the latter.

How topological rearrangements and liquid fraction control liquid foam stability.

The stability of foam is investigated experimentally through coalescence events. Instability (coalescence) occurs when the system is submitted to external perturbations (T1) and when the liquid amount in the film network is below a critical value. Microscopically, transient thick films are observed during film rearrangements. Film rupture, with coalescence and eventual collapse of the foam, occurs when the available local liquid amount is too small for transient films to be formed. Similar experiments and results are shown in the two-bubble case.

Foam invasion through a single pore.

We investigate experimentally the behavior of liquid foams pumped at a given flow rate through a single pore, in the situation where the pore diameter is smaller than the bubble diameter. Results reveal that foam invasion can be observed only within a restricted range of values for the dimensionless flow rate and the foam liquid fraction. Within this foam invasion regime, the liquid content of invading foams is measured to be three times higher than the initial liquid content. Outside this regime, both gas alone and liquid alone invasion regimes can be observed. The gas invasion regime results from the rupture of foam films during local T1, during bubble rearrangements events induced by foam flow, whereas the liquid invasion regime is allowed by the formation of a stable cluster of jammed bubbles at the pore's opening.

Forced impregnation of a capillary tube with drop impact.

We experimentally investigate how the impregnation of porous media can be forced using the initial kinetic energy of an impacting drop. We focus on the scale of a single pore--either hydrophilic or hydrophobic--and thus study the impact of a single drop falling on vertical cylindrical capillary tubes. This experimental configuration therefore differs from the impregnation of a porous media because of the finite volume of the drop and its initial kinetic energy. We observe different limit regimes: at low impact velocity, we recover the classical results for impregnation. The liquid does not impregnate the hydrophobic pore while it is totally sucked into the hydrophilic one. At high impact velocities, the drop is broken in two parts: one part spreads at the top of the surface while an isolated slug is trapped within the pore. We determine the critical speeds for these regimes and obtain a full phase-diagram for our observations. We also stress the characteristics of impregnating slugs namely their volume and their motion within the pores.