ABSTRACT
A novel means of mitigating steam channeling and premature steam breakthrough in steamdrives has been successfully applied in the West Coalinga Field, California. A unique polymer gel system, organically crosslinked in-situ, has shown the ability to divert steam from pre-existing steam channels thus, improving areal steam sweep efficiency.
Small volumes of this specially designed polymer gel system (<500 bbls [<79.5 m3]) were injected in six steamdrive injection wells. The applied treatments required only a minor interruption to continuous steam injection and were performed without any interruption to project production.
Analyses of treatment performances have shown positive results in less than one month. Sustained performance of the first treated injector lasted over six months. Others have continued five months without signs of significant degradation. In treating early steam. breakthrough cases, effective polymer gel placement has reduced casing effluent (steam) rates and casing pressures. Reduced casing pressure combined with increased pumping efficiency has resulted in oil production rate increases. By reducing the volume of live steam produced out of the casing, the project thermal efficiency has been improved through increased utilization of injected heat.
Temperature observation well data have shown substantial reservoir temperature decreases two months after injecting the gel system. These data suggest a redistribution of reservoir heat thus, improved areal sweep.
