In this paper, we experimentally investigate the possibility of formation damage reduction during leak-off and flowback processes by adding surfactants to the fracturing fluid. The experiments consist of three phases: In phase I, we conduct compatibility tests on surfactant solutions to select the compatible surfactant solutions with saline reservoir brine. In phase II, we measure interfacial tension between the stable surfactant solutions and the Montney reservoir oil. In phase III, we conduct a series of core flooding tests on the Montney tight core plug to experimentally investigate the leak-off and flowback processes. To evaluate the effects of surfactant solutions on the formation damage reduction we 1) measure the pressure drop across the core plug during both leak-off and flowback processes, and 2) evaluate the oil recovery factor during the leak-off process.

The results of the compatibility tests show that the anionic soloterra surfactant solutions with hydrophile-lipophile balance (HLB) numbers higher than 10 are compatible with the saline/reservoir brine. Among all stable soloterra surfactant solutions, the soloterra 983 solution shows the lowest interfacial tension (IFT) values. The results of core flooding experiments indicate that the addition of soloterra 983 surfactant into the saline reservoir brine can reduce the pressure drop during leak-off and flowback processes, and therefore, it decreases the possibility of aqueous phase trapping and formation damage in the Montney tight core plugs.

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