PRE AND POST-SWELLING MECHANICAL BEHAVIOR OF A WATER-SWELLING ELASTOMER
Swelling elastomers are a very recent development in the world of advanced polymers, and are being successfully used in the form of packers and other sealing elements in various oilfields. Improved design of sealing elements and prediction of seal performance under different well conditions require a good knowledge of mechanical response of the swelling elastomer. This study reports results of hardness and tensile testing carried out on disc and ring samples of a water-swelling elastomer. Material properties of the elastomer were measured before swelling and periodically after swelling for a total testing time of 15 weeks, under water salinities of 0.6%, 12%, and 25%, and temperatures of 25°C, 50°C, 80°C, and 97°C. Reported results can be used by oilfield engineers as prequalification of the elastomer for downhole applications, and by designers using numerical simulations for improvement of elastomer-based sealing and packer design.
Full Scale Testing of Fast Swell Packer for Shallow Aquifer Applications
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 (50oC 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.
Relationships Between Food Preferences and Food Acceptance Ratings
A study was conducted to assess relationships between food preference ratings and food acceptability ratings. Acceptability ratings for each of two discriminably different samples of nine food items were obtained using the 9-point hedonic scale. Regression analysis indicated that no linear relationship existed between these ratings and either hedonic or frequency preference ratings of the foods. In addition, the range of acceptability ratings was smaller than the range of corresponding’preference ratings. Panelists’expressed preferences had no effect on their assignment of differential acceptance ratings to different samples of the items. Correlations between preference ratings of laboratory panelists and military field panelists were good, in spite of higher absolute preference ratings assigned by the laboratory panel.