Large scale hydraulic fracturing operations are often required for enhancing productivity of wells in shale gas formations. Due to the shally characteristics of the formation rock, the productivity of the hydraulically fractured gas wells seems to be very vulnerable to the damage by the fracturing fluids. The damaging mechanisms are believed to include fluid invasion, proppant embedment, gel filter cake at the fracture face, and the gel residue in the proppant pack. The relative significance of the formation damage due to each of the mechanisms is not clear. This paper presents result of investigations based on a new analytical model. A new analytical well productivity model was developed in this study, considering the matrix cross-flow to long fractures and non-linear influx to short fractures. A new model involves parameters that describe the effects of fracture fluid filtration, proppant embedment, gel filter cake at the fracture face, and the gel residue in the proppant pack on the productivity of fractured gas wells in shale gas formations. Sensitivity analyses with the model show that, fracturing fluid invasion, proppant-embedment layer, gel filter cake residue at the fracture face, and gel residue inside the fracture may reduce well productivity by upto 12.5%, 0.6%, 6%, and 7%, respectively. The significance of the damage to well productivity should not affect gas production rate in a way that would be noticed.

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