Foam has been successfully used for profile control in mature reservoirs for the advantages of easy preparation, selectively plugging capacity, effective profile control and displacement efficiency capacity. However, the stability of foam is a serious problem for scale applications in oilfields. Due to viscoelasticity, strong shearing stability, high temperature and salinity resistance of micron dispersed particle gel (DPG), it was prepared to stabilize foam.
The micron DPG particles were prepared using bulk gel by high shearing method in our lab (C.L. Dai, et al., 2012). A new three phase foam system was successfully prepared by adding micron DPG particles through a modification of Ross-Mile method. The foaming capacity, stability and morphology were systemically investigated. The plugging capacity and enhanced oil recovery capacity of new three phase foam have been also investigated by sand-pack flowing tests.
The effects of surfactant concentration, DPG particle concentration, salinity, oil concentration and gas-liquid ratio on the foaming capacity of three phase foam are systematically investigated. Increasing in surfactant concentration, DPG particles concentration and gas-liquid ratio can improve the foam volume and decay half-life of three phase foam, whereas increasing in salinity and oil concentration decrease the foam volume and decay half-life. By increasing in solution viscosity, adsorption at gas-liquid interface and non-adsorption in solution, the DPG particles can effectively stabilize new three phase foam. Morphology results show that the formed new three phase foam is compact and uniform. Sand-pack experimental results show that the new three phase foam has a better plugging capacity and enhanced oil recovery capacity than traditional aqueous phase foam. The new three phase foam may have a great potential for profile control in mature reservoirs.