Experimental Study on Water-in-Oil Emulsion Stability Induced by Asphaltene Colloids in Heavy Oil

Area of Science:

• Petroleum Engineering
• Physical Chemistry
• Colloid Science

Background:

• Emulsion stability is vital for oil recovery and transportation.
• Predicting and controlling emulsion behavior under varying conditions, especially high-pressure, high-temperature (HPHT), is challenging.
• Asphaltenes and interfacial tension (IFT) play key roles in emulsion stability.

Purpose of the Study:

• To investigate water-oil emulsion formation and stability under atmospheric and HPHT conditions.
• To evaluate the influence of asphaltenes and IFT on emulsion stability.
• To understand the role of formation water in mitigating asphaltene-related challenges.

Main Methods:

• Emulsion stability tests were conducted under atmospheric and HPHT conditions.
• Interfacial tension (IFT) measurements were performed using crude oil, formation water, distilled water, and live oil.
• Asphaltene precipitation was analyzed in the presence of formation water.

Main Results:

• Emulsions showed consistent long-term stability at atmospheric conditions.
• Under HPHT conditions, emulsion stability varied with oil-water ratios (75:25 temporarily stable; 50:50 and 25:75 unstable).
• IFT decreased significantly under HPHT conditions, indicating thermodynamic effects; formation water reduced asphaltene precipitation and enhanced stability.

Conclusions:

• Emulsion stability is highly dependent on reservoir conditions (pressure, temperature, oil composition, water chemistry).
• Formation water is crucial for improving emulsion stability and reducing asphaltene issues.
• Tailoring enhanced oil recovery (EOR) strategies to specific conditions is essential for optimizing oil displacement and recovery rates.