Influence of polymer and surfactant on the aphrons characteristics: Evaluation of fluid invasion controlling

Aphrons fluids are being studied for application in oil well drilling operation. These fluids consist, basically, of polymer and surfactant, which act as thickening agent and microbubbles producer, respectively. The specific function of aphrons is to act in the filtrate reduction of oil reservoirs presenting low pressure and depleted zones. The aphrons charac- teristics were evaluated as a function of type and concentration of polymer (xanthan gum-XG and partially hydrolyzed polyacrylamide-PHPA) and surfactant: anionic (Blue Streak®, sodium dodecyl sulfate-SDS) and nonionic (polyoxide- based copolymer). Through characterization results (size/size distribution of microbubbles, density and air content) and performance evaluation in the invasion controlling, it was possible to conclude that aphrons fluids prepared with SDS, at an optimal concentration but independent of the polymer type, showed better performance, and such result is related to rela- tively higher average diameter and broader size distribution of microbubbles, besides the low density and high air content, in the range evaluated in this study.