Enhancing Heavy-Oil Recovery by Using Middle Carbon Alcohol-Enhanced Waterflooding, Surfactant Flooding, and Foam Flooding

摘要

Previous studies have shown that the addition of low carbon alcohols can significantly enhance oil recovery in surfactant flooding and alkaline flooding. In this paper, the influence of middle carbon alcohols (including n-butanol, n-pentanol, isoamyl alcohol, and n-hexanol) on waterflooding, surfactant flooding, and foam flooding for enhanced heavy-oil recovery was investigated. Foaming tests, oil viscosity measurements, IFT measurements, emulsification tests, and sandpack flooding tests were conducted to investigate the effects and mechanisms for enhanced heavy-oil recovery by addition of middle alcohols. The results show that the added middle carbon alcohols has no obvious effect on the reduction of IFT between oil and surfactant solution; however, they can reduce the viscosity of heavy oil and can greatly enhance the foaming property and the emulsifying property of surfactant solution. The sandpack flooding results show that the heavy-oil recovery can be enhanced significantly through the addition of middle alcohols in water flooding, surfactant flooding, and foam flooding, especially in foam flooding. The reduction of oil viscosity, the entrapment of emulsified oil droplets, and the enhancement of foaming property by the addition of alcohols contributes to the improvement of sweep efficiency. Meanwhile, the enhancement of emulsifying property of surfactant solution by addition of alcohols facilitates the improvement of displacement efficiency.