Oil reservoirs in the Lloydminister region, Canada, arernproduced through the process of Clod Heavy Oil Productionrnwith Sand (CHOPS). Implementation of CHOPS in thesernfields causes the formation of wormholes, which leads tornproduction of excessive water and abandonment of the wells.rnIn order to reduce the excess water production fromrnwormholes, variety of techniques have been suggested andrntested with minimal success. Blocking the wormholes by thernmeans of clay, polymer-gel systems, and gel-foams are amongrnthe proposed methods. This paper presents the results of arnseries of experiments conducted in order to develop and testrnthe applicability of a new gel-foam system for blockingrnwormholes in oil reservoirs. As a result, a new gel-foamrnsystem was invented that creates stable foam in wormholes forrnthe duration of gelation time. The composition of the gel-foamrnwas based on polyacrylamide cross linked with chromium(III),rnplus a mixture of solutions of two commercially availablernsurfactants. These commercially available surfactants wererntested at various concentrations and ratios to develop the mostrnstable gel-foam system. An experimental set up was designedrnand built which allowed for two layers of unconsolidated sandrnas the matrix separated by a high permeability wormholernbetween them. The effect of various sizes of wormholes on thernperformance of this gel-foam system was tested. Allrnexperiments were conducted at atmospheric pressure andrnconstant temperature of 30℃, with some experiments in thernpresence of residual oil. For all the experiments the residualrnresistance factors to the flow of water in high permeabilityrnpathways were in the range of 25 to about 200. The resultsrnobtained are clear indication of the effectiveness of this newlyrndeveloped gel-foam system for blocking wormholes and otherrnhigh permeability pathways in reservoirs.
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