Influence of the wettability of particles on the morphology and stability of crude oil–particle aggregates in synthetic produced water

• Produced water treatment affected by crude oil–particles interactions.
• Three phase contact angle related to morphology of oil–particle aggregates.
• Formation of Pickering emulsions for high three phase contact angle.
• Crude oil–particles irregular aggregates at lower contact angles.
• Efficient drops coalescence for low content of particles at interface.

Handling and treatment of produced water is becoming an increasing part of oil and gas production. A major challenge in this respect is removal of oil drops stabilised by particles. Understanding the influence of interfacial and wetting properties of crude oil–particle+ systems on the formation of particle stabilised emulsions is therefore essential. Elucidating these relationships was the aim of this investigation. Synthetic produced water containing different particles and crude oil were studied. The morphology of aggregates formed by crude oil drops and particles was strongly related to the contact angle (θwo) at the water–oil–particle interfaces. High θwo resulted in formation of particle stabilised emulsions, while less defined aggregates were formed at lower θwo Furthermore, coalescence of drops was related to the coverage of particles at the interface. Stable drops covered by particles were only seen when the amount of particles was significant. Otherwise drops tended to coalesce, likely due to particle bridging.

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