Abstract

Alkali is an important component for alkali/surfactant/polymer technology for enhanced oil recovery. The mechanism and advantages of traditional inorganic alkali for enhanced oil recovery (EOR) was reviewed in this paper. But the weakness of inorganic alkali, such as scaling, corrosion and high cost of water treatment, are significant too. This paper comparesthe use of a type of organic alkali ethanolamine for EOR with inorganic alkali (NaOH) for alkali-polymer (AP) and alkali-surfactant-polymer flooding. The solution of 0.1 wt% polymer (FLOPAAM 3130S) was mixed with different concentrations of ethanolamine and NaOH respectively. The rheological and dynamic properties of the combination of alkali and polymer were analyzed. The results show that the polymer solution with ethanolamine has better shear viscosity and elasticproperties at room temperature. Surfactant (Alfaterra 123-8S-90) with concentration of 0.15 wt% was added into each alkali-polymer solution. No significant change was observed in rheological properties of alkali-polymer solutions with and without surfactant. Emulsification test shows that ethanolamine has better performance with oil. Injectivity tests were also conducted. The results indicated that RRF for ethanolamine-polymer solution is always higher at each flow rate tested in comparison to NaOH AP solution which is beneficial for oil recovery. Core flooding experiments were tested in homogeneous sand pack and the performance of ethanolamine-polymer and NaOH-polymer was compared. The pressure comparison during flooding shows that it has higher injection pressure in ethanolamine conditions which result in good sweep efficiency. The ethanolamine-polymer flooding showed a significant increase in oil recovery (15.33%) over NaOH-polymer flooding. After addition of surfactant, the total recovery improves by 14.8% for ethanolamine-polymer-surfactant flooding over its inorganic counterpart. The results of core flooding indicate that ethanolamine has better performance in EOR for AP flooding and ASP flooding. Ethanolamine can become a potential alkali and can replace NaOH for EOR.

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