Abstract
A polymer treatment has been successfully applied in a Gaz-de-France gas storage well facing excessive water production problems limiting its maximum gas flow rate. The well was located in a limestone reservoir submitted to an active bottom aquifer. To reduce the risk of well impairment while enhancing the efficiency to fight water coning, the polymer slug was injected into the half of the open interval located at the bottom of the reservoir. A study consisting of laboratory core tests and numerical simulations aimed at sizing polymer slug and concentration before performing the treatment. The level of water permeability reduction to reach was fulfilled with single polymer adsorption without the need of adding cross-linker.
After a period of two years where no significant effect on water production occurred, the well progressively improved its performances while water production remained at the same level in neighbour wells. After ten years of survey, the well, which was one of the worse of the storage, became one of the best, capable to sustain high levels of gas production with low water. The delay in well response is probably due to the high water saturation level of the reservoir surrounding the wellbore consecutive to the injection of the polymer slug. The results show that the technique, while easy to handle, gives remarkably efficient long-lasting effect.
