Flow and plugging behavior of foams in fractures of fractured reservoirs

The development of fractured reservoirs can benefit from the use of foams, as they can enter fractures to increase the flow resistance of high-permeability zones, thereby redirecting fluid flow toward low-permeability zones. This can reduce the leak-off of working fluids during flow and improve the reservoir stimulation efficiency. The fracture visualization models applicable to micro-scale foam flow are developed to fully reveal the flow and plugging behavior of foams in micro-fractures. The models are accompanied by the implementation of the microfracture foam flow experiments. The experiment results show that with the increasing flow rate and foaming agent concentration, foams become smaller, more homogeneous, stable, and capable of plugging micro-fractures. However, both significantly large and small gas-liquid ratios degrade these properties of foams. For optimal results, a gas/liquid flow rate of 100-150 mu L/min, a gas-liquid ratio of 2-4, and a foaming agent concentration of higher than 0.75 wt% are recommended. During foam flow, foams preferably enter wider fractures, where they accumulate and become trapped, plugging the flow channels. This results in a diversion of the subsequent foams towards narrower fractures, leading to more effective plugging of the fractures.