A full scale experimental setup was designed and commissioned for testing of swelling elastomer seals against a casing (cased hole) and formation (open hole). Actual replicate of wellbore was designed with varying inside diameters and roughness to reproduce the effect of actual formation. The Dynaset packer mounted on 7" tubular was allowed to swell against a 9-5/8" casing, while the fast swell packer mounted on 9-5/8" tubular was allowed to swell against the 12-1/4" replicated well bore. The fast swell elastomer will bridge the annulus between casing and OH to prevent total losses and to allow cement to surface. Recent drilling condition required the development and testing of fast swell packers to isolate shallow aquifers. Under actual shallow-aquifer field conditions (50°C and 0.5% salinity) 70% swelling was expected in 24 hours. However, under fresh water the swelling was achieved in more than 24 hours. It took approximately ten days for the elastomers to completely fill the irregular cavities in the replicated well bore. The test demonstrated the way the elastomers fill the asperities and was worth of observation for field engineers. The Dynaset packer at low salinity took 4 weeks to completely seal the gaps. Under high salinity it takes approximately 3 weeks for complete sealing. The measured-cum-calculated results showed that the swelled elastomers have developed an internal pressure of 50‒70 bars against the leakage. Dismantling of the test setup showed that the elastomer has swelled to brain like surface structure, which was a startling observation and needs further work. Isolation of shallow aquifers and fractured formations has been a major challenge for many years in Oman. The requirement for zonal isolation of the shallow aquifers is often compromised by the total losses. The simplicity of solution using swellables will avoid a cocktail of chemicals and will open new applications to materialize low cost wells.