Foam Analysis at Elevated Pressures for Enhanced Oil Recovery Applications

Abstract

A novel foam analyzing system is presented in this work for a systematical and scientifically based investigation of foaming capacity, structure, and stability under process conditions relevant for enhanced oil recovery. The foam height and structure are detected simultaneously as a function of foam age. The apparatus has an extended optical access by means of three tongue-shaped high-pressure windows. A special arrangement of prisms allows for the detection of bubble shapes and size distribution at the same time. The results show a substantial difference of foams generated using compressed gases compared to atmospheric conditions. At pressures rising to 15 MPa, nitrogen foams become increasingly stable, while instable and metastable CO2 foams require a special selection of surfactants and foam stabilizers. As a result of the higher solubility of CO2 in the film phase, Ostwald ripening and coalescence play an important role in decay of CO2 foams, while these mechanisms are hardly observed in N2 foams.