Surfactant Drive Process in Ultra-Tight Fractured Reservoirs for EOR

We explore the viability of drive processes other than huff’n’puff—using surfactant flooding for tight formations. At least one fracture must be connect a given injector-producer pair to allow sufficient flow. If too few fractures are present and/or the primary fracture is too conductive, the expensive surfactant formulation channels between the well with an unacceptably low oil cut. This work quantifies the conductivity and intensity of additional fractures that are needed to provide a workable EOR process. Based on laboratory studies of surfactant imbibition and drive processes, various comparisons are made among the conditions of remaining oil saturation, initial water saturation, surfactant concentration.

The laboratory result shows a positive potential of oil recovery enhancement over brine alone using surfactant flooding with naturally fractured cores from Bakken Formation. Our research indicates: (1) Surfactant flooding for tight rocks with low permeability (10-3 md) may be feasible for oil recovery enhancement under certain conditions. (2) The balance is characterized between achieving acceptable rock exposure (to the surfactant), imbibition and oil displacement rates, and oil cut versus acceptable injected and produced fluid rates.

Because of ultra-low permeability and fractures distribution, surfactant flooding represents an interesting new approach to oil recovery from tight formations.