Abstract:
At present, among the conventional fracturing and acidizing in oil fields, using them as cleanup additives: fluorocarbon surfactants generally contain perfluorooctyl carboxylic acid and its salts (PFOA), perfluorooctyl sulfonic acid and its salts (PFOS). The fluorocarbon chain of them is relatively long, facing the problem of difficult degradation and persistent bioaccumulation. In this paper, starting from the selection of fluorocarbon raw materials, the biodegradable short fluorocarbon chain raw materials were selected as the synthetic materials of fluorocarbon surfactants. Through optimizing the molecular design and structure, the system products containing fluorocarbon surfactants with high-efficiency, environment-friendly fracturing and acidizing on site were screened and developed. The results showed that the gimini short-fluorocarbon surfactant has strong surface activity, and the critical micelle concentration is as low as 3.0×10
-4-3.4×10
-4 mol/L and
γcmc=16.0 mN/m. The new type of cleanup additive has excellent effect, and the rate of cleanup is 57.1% and 63.6% respectively. It has been successfully applied in the construction of cementitious acid acidification in ST-8 well and the construction of sand fracturing in H-201 well.