A testing methodology was developed to examine the effectiveness of oil-swellable additives in cement slurries by evaluating the capability to shut off hydrocarbon fluid flow through a crack initiated in the cement. An open-loop testing fixture was used to investigate the effect of oil-swellable additive concentration and environmental temperature, using Kaydol mineral oil as a test fluid. Under a pressure differential of approximately 2 psi/in., test results indicated that a concentration of 10% by volume of additive relative to a 15.5 lbm/gal Class G slurry was sufficient to significantly reduce hydrocarbon flow in a crack in cement at a temperature of 160°F in an average time span of 48 hr and in shorter time spans with an increase in temperature.

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