An investigation into surfactant stabilized, non-aqueous and semi-aqueous foam for enhanced oil recovery
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Foam serves as an important role in enhanced oil recovery processes involving gas injection since it hinders flow and acts as a mobility control agent. Significant work has been presented for the utilization of water as the continuous, external phase of the foam, but opportunity exists in using a non-aqueous compound instead. Y-grade, a raw blend of NGLs, has been becoming more available with the increase in wet gas, shale plays over the last decade. Coinjecting or alternating the injection of nitrogen and y-grade with a foam stabilizing additive, such as a surfactant, may provide a recovery scheme with both a strong displacement efficiency due to the miscible nature of the y-grade with oil and a strong sweep efficiency due to the mobility control provided by the y-grade-based foam. The foaming ability of y-grade was investigated by using pentane as a stand-in since it is the lightest alkane that is still readily a liquid at room conditions. Thirty-eight additives spanning a wide range of chemical properties were evaluated for their potential to generate and stabilize the non-aqueous foam. In addition, both water and non-aqueous liquids were investigated to see if they would increase the foaming potential of the y-grade or pentane by being mixed as a secondary component. Concurrently, a procedure and experimental assembly was created to blend a synthetic y-grade containing ethane through octane. This synthetic y-grade was used to validate the assumptions made in the pentane screening tests by further blending in nitrogen, water, and other additives into pressurized visual cells for observation. In addition, the y-grade was used in a coreflood as a base case for a planned series of tests for y-grade-based foam within a porous media for oil recovery purposes.