Hydraulic fracturing operations, carried out by injecting large volumes of water, cause invasion of the injected water into the formation and trapping due to capillarity. This invasion, also termed as water blocking, can cause a reduction in the gas well productivity by reducing the relative permeability of gas with respect to water. The flow of gas toward the wellbore/fracture during production well will result in the removal of water block through viscous displacement as well as evaporation, which occurs primarily due to gas expansion over long period of time. However, recent observations from field show that the productivity of hydraulically fractured wells improves after a period of shut-in leading to a speculation as to whether capillary suction is responsible for the clean-up of water block which eventually leads to productivity improvement. In this work, we solve for the gas relative permeability improvement of the invaded zone of a fractured well accounting for both evaporation and capillary suction. The conservation equations, for both water and gas, are solved numerically to obtain water saturations and gas relative permeability in the damaged zone. Simulations, of gas relative permeability with time, show that when water invasion depth is small, capillary imbibition is the dominant clean up mechanism. For larger depth of invasion, both capillary imbibition and evaporation contribute to the clean-up of water-block leading to the improvement of gas relative permeability in the invaded region. However, when the viscosity of invaded liquid is high, and the liquid mobility is reduced, capillary imbibition maybe negligible and evaporation becomes the dominant clean up mechanism. Our results show that the inclusion of capillary driven flows is important in the prediction of gas well deliverability calculations when water blocking occurs. This study presents a model, combining both viscous removal and evaporation, to calculate the evolution of fracture face skin due to progressive removal of waterblocks and hence well productivity under field conditions.

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