Understanding Foam Flow in Rough Carbonate Fractures

Abstract

Abstract Foams are used to improve the sweep efficiency during oil recovery in carbonates. Carbonates have high permeability fractures and vugs which can alter the foam structure, potentially changing the flow and sweep efficiency of the foam. In this paper, we investigate how the roughness of fractured carbonates affects the foam structure stability. The behavior of foam in a rough and saw-cut fractures was observed experimentally and with simulations using Lattice Boltzmann method to qualitatively assess their structure. In the experiments, it was observed that a fracture with a rough surface decreased the collapse of foam lamella and increased apparent viscosity in comparison to the saw-cut fracture. In the temperature range of 40°C to 60°C, foam structure was more stable at lower ends of this temperature range. In the simulations, we observed that the foam bubbles in the smooth fracture tended to undergo Ostwald ripening. This led to a more heterogeneous distribution of bubble sizes inside the smooth fracture. Whereas the average size of the polygonal bubbles was fairly small and uniformly distributed across the rough fracture, leading to more stable foams.