Polymeric Surfactant for Enhanced Oil Recovery- Microvisual, Core-Flood Experiments and Field Application

Abstract

Abstract Phase separation, which decreases the synergistic effect, are observed during amount of surfactant/polymer (SP) or alkali/surfactant/polymer (ASP) flooding field applications and laboratory experiments. The idea of adding hydrophobic groups to a water-soluble polymer is to make polymeric surfactant that could be applied in Enhanced Oil Recovery (EOR). However, pole-scale displacement mechanisms and field performances of polymeric surfactant have not been investigated throughtly. In this work, we synthesized two types of polymeric surfactants and evaluated their physi-chemical properties, including chemical structure, rheological characteristic, emulsification and salt tolerance. Beside these physi-chemical property tests, a micro-visual model and core-flooding tests were performed to investigate the efficiency of polymeric surfactant flooding to recover the bypassed or trapped residual oil after water flooding. Finally, field performances of polymeric surfactant were estimated by monitoring the production dynamics and development index from a pilot test in Daqing oilfield. Results show that the polymeric surfactant has characteristics of strong viscosity, salt-resistance and emulsification. The high viscosity of the polymeric surfactant gurantantees a better mobility control than the ordinary polymer. What's more, the enhanced swept volume, emulsifiability and high elasticity makes the polymeric surfactant flooding has higher recovery factor than traditional polymer during chemical flooding. The heterogeneous core flooding experiments show that extra 10% overall recovery can be obtained with polymeric surfactant flooding after traditional polymer flooding. The application of the two types of polymeric surfactants in the pilot area shows that polymeric surfactants make the middle and low permeability zones absorb more water than traditional polymer flooding. If the surfactants were injected after water flooding, oil recovery can be improved by more than 20%, and significant reduction in water cut. With these unique properties and good performances for trials in the pilot test, polymeric surfactants can be considered as a replacement to the traditional polymer in highly heterogeneous reservoirs after water flooding or polymer flooding.