Impacts of permeability stress sensitivity and aqueous phase trapping on the tight sandstone gas well productivity - A case study of the Daniudi gas field

Abstract Permeability stress sensitivity and aqueous phase trapping have significant effects on the gas well production. An experimental study was conducted to investigate the individual and the combined impacts of the increasing effective stress (i.e., permeability stress sensitivity effect) and the formation water saturation (i.e., aqueous phase trapping effect) on the permeability of the rock samples obtained from two different tight sandstone gas formations. Results have shown that increasing effective stress and near well formation water saturation can both cause significant formation damage. Moreover, we have found that the increasing water saturation made the rock more susceptible to damage due to the permeability stress sensitivity. Similarly, as the effective stress increased, the degree of the formation damage due to the aqueous phase trapping also increased. Overall, the mutual interaction between the permeability stress sensitivity and the aqueous phase trapping synergetically created even higher formation damage effect. From the field operation point of view, both the proper selection of the drawdown pressure across the completion and the use of the suitable aqueous phase trapping removal techniques are equally critical for sustaining the productivity of the tight sandstone gas wells at the economical level in the middle and the later stages of the field development. The use of a single solution approach towards the remedy of only one of the two effects may not improve the gas well productivity very effectively.