In this paper, we developed a laboratory protocol to evaluate the performance of three microemulsion (ME) additives in fracturing water for enhanced oil recovery. We applied the protocol on oil, brine, and core samples from two wells completed in the Montney (MT) Formation in the following steps: 1) Performing bulk-phase tests to evaluate fluid properties, particle size and stability of nanodispersions (ND) generated by mixing the ME additives with water, 2) Characterizing natural wettability of the core plugs by spontaneous imbibition and contact angle tests, and 3) Evaluating surfactant-assisted imbibition oil recovery during the shut-in time by conducting systematic contact-angle and counter-current imbibition tests under different conditions of brine salinity.

Results of fluid-fluid tests, showed that one of the MEs, gives the smallest particle size (36.54 nm), the lowest IFT (0.1753 mN/m), the closest oil-solubility to Winsor III, and the best stability compared with other MEs. In rock-fluid experiments, performed by the candidate ME from fluid-fluid tests, we observed higher and faster imbibition oil recovery by mixture of ME with tap water (52% oil-recovery) compared with mixture of ME with brine (16.6% oil-recovery). In addition, adding the ME additives in brine does not improve imbibition oil recovery compared with the brine without ME additive (7.5%).

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