Supercritical CO2 Foam Stabilized by a Viscoelastic Surfactant in Fractured Porous Media: The Effect of Fracture Surface Roughness

Foam flooding has been used for gas conformance control during enhanced oil recovery (EOR) in heterogeneous reservoirs. The application of foam flooding in naturally or hydraulically fractured reservoirs has recently been gaining attention. There are, however, limited studies on supercritical CO2 (scCO(2)) foam behavior in the fractured system. Specifically, the impact of fracture properties such as aperture size, surface roughness, and fracture orientation in natural rocks are not well studied. In this work, we investigated the behavior of scCO(2) foam stabilized by a viscoelastic surfactant in fractured systems. The apparent viscosity of foam in fractured and nonfractured cores was compared. Furthermore, the effects of fracture surface roughness and crude oil on foam behavior were determined. We found that the fracture surface roughness positively affects the apparent viscosity of foam in the absence and presence of crude oil. Also, the formation of the complex structure of the water-oil-CO2 system during oil-foam co-injection may serve a major role in causing a significant apparent viscosity.

Automated summary

The roughness of fracture surface can positively affect the apparent viscosity of foam, both with and without crude oil. The complex structure of the water-oil-CO2 system during oil-foam co-injection may play a significant role in increasing the apparent viscosity.