The technology of multi-stage fracturing of horizontal wells made the development of shale gas reservoirs greatly successful during the past decade. During operations, a large amount of fracturing fluid is injected into the reservoir to create the fractures. Operators have reported that only a small fraction of this fluid (10 to 40%) has been recovered during the flowback process, but this study observed much higher load recoveries (up to 60%) during the long-term shale gas well production period.

In this work diagnostic plots are applied to provide indications of fracturing fluid flow regimes as well as a diagnosis of any potential production problems. Then formation pressure and temperature are used to estimate the water solubility level in different shale gas reservoirs to determine whether the fracturing fluid production mechanism is water vaporization. A log-log plot of water-gas ratio versus cumulative gas production shows apparent flow regimes that may represent displacement seen as a negative half slope trend and vaporization seen as negative unit slope trend. The water production mechanisms in the Horn River shale is displacement followed by vaporization, while the water production mechanisms in the Barnett Shale is displacement dominated.

This work is critical for understanding existing shale gas well performance and improving shale gas well designs. Water produced during drainage directly impacts well performance, while water produced by vaporization has less impact. Well interference represents intersecting hydraulic or secondary fractures, and this could be an indication that wells could be spaced further apart.

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