Concerns by regulatory authorities regarding cumulative effects or reservoir adsorption of hydraulic fracturing fluid have increased, with an overall focus on fracturing fluid additives. Operators do not always obtain adequate core materials to fully evaluate additive effectiveness or to belay regulatory concerns regarding the cumulative interaction effects of fracturing fluids with the formation. Without these materials, operators are often required to representatively sample post-fracturing fluids and hypothesize the volumes of additives remaining in the formation, material balancing on a qualitative post-frac testing basis, which can be highly unrepresentative.

This paper presents the results from a study from a prospective shale gas interval where formation materials or cuttings were sampled across a representative producing interval, offsetting the proposed multistage fracturing treatment. The processes of how the fluid formulation was optimized using established qualitative procedures for clay sensitivity (i.e., capillary suction testing) and then further evaluated for surfactant requirements (e.g., tensiometry) are demonstrated. Following final fluid formulation, interactive testing with reservoir materials was performed, providing insight into the level of fluid and additive interaction that might result between the formation and the proposed fluid. This study provides practical approaches to testing and defines benefits and limitations of employing these approaches to belay potential concerns evolving related to fracturing fluid interaction within reservoirs and their cumulative effects.

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