Experimental study on stability and rheological properties of aqueous foam in the presence of reservoir natural solid particles

Gas injection and especially CO2 flooding has been applied in many oil reservoirs globally to increase oil recovery factor in addition to its environmental friendly aspects. However, difference between fluid viscosities and densities, can cause interface instability where gas override and fingering may expedite gas breakthrough. Different types of foam have been proposed to improve interface stability. Yet, a major uncertainty is interaction of foam with natural reservoir particles which may improve or downgrade the performance and stability of foam. In this study we examined foam stability through solid-fluids interactions between solid particles of hydrocarbon reservoirs and aqueous foam. We tested five common reservoir particles of calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate and iron oxide with different surfactant and particle concentrations. It is found that stability of foam in the presence solid particles is a function of density, shape, size, and wettability of particles where monolayer, bilayer of network or particles stabilise foam lamella or rupture foam structure. Results show that solid particles of calcium carbonate, barium sulfate and strontium sulfate enhance the thermodynamic stability of foam. This is due to the distribution of semi-hydrophilic solid particles, which form mono- and multi-layers of particle chains in foam lamellae and plateau borders. On the other hand, solid particles of iron oxide and calcium sulfate destabilise foam where particle swelling, adsorbed surfactant solution and settlement into liquid phase due to their high densities were observed. The results suggest that a comprehensive study of liquid and solid interaction is critical in design of any foam for enhanced oil recovery processes.