The depression of the current global oil market renders the majority of chemical EOR projects worldwide unprofitable, especially in china. Therefore, economic alternative technologies must be quickly developed. This paper evaluated the potential of a smart pre-formed emulsion flooding EOR in Block 9 based on the reaction between alkali and highly acidic crude oil. The static properties and dynamic displacement behaviors of the emulsion were thoroughly investigated. Particular emphasis was placed on the relationship between emulsion stability, droplet particle/pore radius matching, and EOR efficiency. The experimental results showed that the petroleum acids of the crude oil reacted with alkali (NaOH), and producing neutral emulsions (pH≈7.0). The emulsion rheology and morphology were strongly dependent on oil water ratio. From the economic point, the oil/water ratio of 0.5:9.5 was used to prepare two types of O/W emulsions (unstable and stable emulsions) with different particle sizes. The core flooding tests proved that a higher pressure during emulsion injection was generated than that of water injection due to Jiamin effect induced by the dispered oleic phase. As a consequence, the oil recovery factor was further improved by 6-17%. High matching factor and emulsion stability accounted for more significant EOR effect as we observed.

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