A recent study (SPE paper 16728) described a preliminary investigation of the effects of some commercial gelants on reduction in CO2 permeability. That paper presented a method for examining gelant systems by vial tests, core tests, and two-dimensional, flow visualization studies in high-pressure, glass micromodels. For the preliminary study, tests were conducted with CO2, San Andres crude oil, and brine at 1500 psi and 105°F to simulate west Texas/southeast New Mexico conditions. The micromodel studies were coupled with the core tests to assess the pore-level mechanisms responsible for permeability reduction. Each of these commercial gelant systems demonstrated some deficiency in the desired performance in the brine/CO2 systems under investigation.

This paper presents follow-up lab-scale studies with newer gelant systems that are shown to be more stable under the same brine/CO2 conditions. Gelation kinetics are discussed, and results of core tests with a phenolic gel and a vinyl gel are described. These gels are more rigid than the gels first investigated, and the micromodel studies indicate that they are much more effective in remaining stationary in channels or high-permeability flow paths.

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