Development and selection of chemical systems for miscible waterflooding
Three water-external surfactant systems were compared for stability at various electrolyte concentrations and for efficiency of oil recovery. The effect of the type of reservoir rock used was noted for the amount of surfactant adsorption and for efficiency of oil recovery. Mahogany sulfonates were combined with water (90-95 percent), isopropyl alcohol, up to 30,000 ppM TDS, and up to 500 ppM calcium ion (hardness) to form the first water-external surfactant slug. The second type of slug contained gas-oil sulfonates with 90-95 percent water, alcohol (40,000 ppM TDS, 2,000 ppM Ca/sup 2 +/) or sulfated ethoxylated alcohol (60,000 ppM TDS, 3,000 ppM Ca/sup 2 +/). The final type of surfactant slug contained polybutene sulfonates with 90-95 percent water, ethoxylated alcohols (95,000 ppM TDS, 5,000 ppM Ca/sup 2 +/) or amphoteric-type cosurfactants (150,000 ppM TDS, 9,000 ppM Ca/sup 2 +/). Cores from the Tensleep sand reservoir in Wyoming contain anhydrite in the rock pores which release Ca/sup 2 +/ at about 1,000 ppM. Tertiary oil recoveries gave 89 percent PV using a polybutene sulfonate slug, about 17 percent PV using a gas-oil sulfonate slug, however the mahogany sulfonate slug was not stable under these conditions. The polybutene sulfonate slug is stable over the widest salinity and hardness ranges, is stable for the highest concentrations of monovalent and divalent metal ions, and has the highest recovery efficiency.All surfactants were adsorbed to a greater extent in limestone cores than in Berea sandstone cores. Using a mahogany sulfonate slug, it was shown that sandstone permitted a more efficient recovery than limestone.
- OSTI ID:
- 7301369
- Country of Publication:
- United States
- Language:
- English
Similar Records
Method for waterflooding petroliferous strata
High water content oil-external micellar dispersions