Effect of emulsifying property of an alkaline-surfactant-polymer system without ultra-low interfacial tension on enhanced oil recovery

Abstract

The objectives of the work were to establish a new method of evaluating emulsifying property of ASP system, design a new-type ASP system without ultra-low interfacial tension (IFT) based on its emulsifying property, and test its capability to enhance oil recovery. A new-type ASP system without ultra-low IFT was designed. The composite performance indexes of the new-type ASP system named formula 1 and conventional ultra-low IFT ASP system named formula 2 applied in Daqing oilfield were evaluated. The Turbiscan Stability Index (TSI) parameter was utilized to characterize the stability of emulsions. Also, the emulsions were evaluated in terms of droplet size distribution, ζ potential, and rheology. The average droplet sizes of formula 1 emulsion and formula 2 emulsion were 4.6 μm and 11.4 μm respectively. Results showed that formula 1 had a better emulsifying power, a better stability of emulsion with lower TSI, smaller average droplet size, and higher absolute value of ζ potential than formula 2; thus, it had a higher composite performance index compared with formula 2. Furthermore, the formula 1 emulsion viscosity gave values higher than the viscosity of formula 2 emulsion. The experimental results showed that the additional oil recovery of formula 1 was always higher than that of formula 2. The non-ultra-low IFT ASP system with better emulsifying property had an approximately similar effect on enhanced oil recovery compared with the conventional ultra-low IFT ASP system. This research examines and analyzes the new outcomes from implementing the new-type ASP system without ultra-low IFT to improve oil recovery. Ultimately the gained results from this work indicate that the new-type ASP system can be applied to enhance oil recovery, and project a roadmap for ongoing and future work; however, more investigations are required to be conducted.