Correlation Between Foam Flow Structure in Porous Media and Surfactant Formulation Properties

The optimization of foam injection in porous media for enhanced oil recovery or soil remediation requires a large screening of surfactant formulations. Tests of foam stability in vials often used quick criteria to accelerate selection and ensure performance in porous media. Using a selection of surfactant formulations of different chemistry and foam behaviors, the correlation between foam in vials and in porous media is investigated. Along with foam stability, foamability which quantifies the ability to create foam is shown to play a role in the maximum apparent viscosity. This is a first evidence that foamability is a key parameter for the maximum apparent viscosity reached in a steady state of apparent viscosity. To account for the relative contribution of foamability and foam stability, a parameter is inspired from the widely accepted model of population balance. These results support a workflow based on large foam screening in a first step and sandpack experiments in a second step, prior to more representative but longer coreflood tests. Finally, these experimental data emphasize the relevance of population balance simulations as a description based on experimental measurement. Second, the flow visualization in the sandpack allows the extraction of a local velocity of the liquid in the flowing foam. This parameter gives an experimental evidence that the transition between the high-quality and low-quality regime corresponds to a change in the efficiency of foam lamellae network to transport gas concomitantly to liquid. The local liquid velocity also represents an indirect and easy measurement of flow structure, and it is shown to change from one formulation to another. This observation highlights the complex relation between local microstructure and physical chemistry of surfactants.