Investigating the Impact of Polymers on Clay Flocculation and Residual Oil Behaviour Using a 2.5D Model

Area of Science:

• Petroleum Engineering
• Enhanced Oil Recovery
• Colloid and Surface Science

Background:

• Surfactant-polymer (SP) flooding enhances oil recovery but can suffer reduced injection-production (I/P) capacity.
• Residual oil, particularly adsorbed intergranularly, remains a challenge in secondary composite flooding (SCF).
• Polymer-clay interactions, specifically kaolinite (Kln) flocculation, are implicated in reduced SCF efficiency.

Purpose of the Study:

• To investigate the mechanism behind the decline in I/P capacity during SP flooding.
• To elucidate the role of polymer-clay interactions in trapping residual oil.
• To understand how kaolinite flocculation affects crude oil displacement.

Main Methods:

• Utilized a microscopic visualization displacement model (MVDM).
• Employed microscopy techniques to observe particle migration during SCF.
• Simulated reservoir migrating particles using kaolinite water suspension (Kln-WS).
• Observed displacement effects on Kln-WS, crude oil (CO), and their mixtures.

Main Results:

• Observed that polymers act as flocculants, promoting kaolinite flocculation during displacement.
• Demonstrated that kaolinite flocculation increases the viscosity of crude oil.
• Identified the formation of high-viscosity mixtures of migrating particles and crude oil.
• Showed that these mixtures accumulate in pores, hindering further oil displacement.

Conclusions:

• Polymer-induced kaolinite flocculation is a key mechanism reducing SCF efficiency.
• The formation of viscous oil-particle aggregates leads to oil trapping.
• Understanding and mitigating these interactions is crucial for optimizing EOR strategies.