One of the methods used to extend the production level and durability of low permeability gas wells is by conducting refractures. Although many case histories have been reported in the literature, limited information reporting the refracs long term performance is available. The reasons for this can be summarized as follows: - Any study conducted to test (Build Up) involves killing the well or at least controlling the production pressure. This condition generates changes in the production regime which generates certain uncertainties in the measurements precision. - The testing procedure may cause some type of formation damage that impedes recovering the original production regime. - Finally, if the well has a high production regime, long testing periods means losses in gas production. This paper presents a study performed on a low permeability sandstone gas well located at the Neuquina basin, Argentina, were the performance of two fractured zones were evaluated by means of a Build up test conducted without killing the well. A snubbing unit was used to carry out several operations as removing the production installation, applying zonal isolation using plug and packer among other tasks. Both zones under study had been stimulated three years before conducting the study using a CO2 foam fracture fluid. The operational sequence, stimulation treatments analysis and closure stress interpretation provided valuable information to understand the fractures aging response and to define and design re-fractures.
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