Salt-Responsive Phenol Formaldehyde Resin: Changes of Interface Energy on the Aggregation Process

Area of Science:

• Colloid and surface science
• Materials science
• Petroleum engineering

Background:

• Phenol formaldehyde resins (PFRs) are utilized as colloidal oil displacement agents in enhanced oil recovery (EOR).
• The aggregation-dispersion and charging behavior of PFRs significantly influence suspension rheology and reservoir plugging efficiency.
• Understanding these properties is crucial for optimizing PFR performance in EOR applications.

Purpose of the Study:

• To investigate the aggregation-dispersion and charging behavior of PFR particles in various salt solutions.
• To determine the critical coagulation concentration (CCC) and critical coagulation ionic strength (CCIS) of PFR suspensions.
• To evaluate the applicability of the Derjaguin-Landau and Verwey-Overbeek (DLVO) theory, modified by interface energy, in explaining PFR aggregation.

Main Methods:

• Turbidity measurements to assess particle aggregation.
• Dynamic light scattering (DLS) to determine particle size and aggregation rates.
• Electrophoretic light scattering (ELS) to measure ζ-potential and surface charge.
• Application of the triple-layer surface complexation (TL) model to analyze cation adsorption and surface characteristics.
• Utilizing modified DLVO theory to explain aggregation behavior.

Main Results:

• Aggregation rates and ζ-potential of PFR particles were measured across different salt concentrations (NaCl, MgCl2, CaCl2) and mixed ionic systems.
• Critical coagulation concentrations (CCC) and critical coagulation ionic strengths (CCIS) were determined for various ionic conditions.
• The TL model provided insights into cation adsorption and PFR particle surface characteristics, linked to interface energy.
• The modified DLVO theory successfully explained the aggregation behavior of PFR particles in multi-ion systems.

Conclusions:

• The study elucidates the aggregation-dispersion and charging mechanisms of PFR particles under varying ionic strengths and compositions.
• Interface energy plays a significant role in governing cation adsorption and surface characteristics of PFR particles.
• The Derjaguin-Landau and Verwey-Overbeek (DLVO) theory, when modified by interface energy, demonstrates strong applicability in predicting PFR particle aggregation in complex ionic environments, crucial for EOR.