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How the age of the emulsion impacts demulsification? and case study！

2025-08-07

How are cured oil emulsions formed

Crude oil emulsions form when water and crude oil mix under specific conditions, creating a stable mixture where one phase (usually water) is dispersed as droplets in the other (oil). This process is driven by several factors:

Presence of Water and Oil
Do you have a minimum order quantity?
Agitation or Shear
Natural Emulsifiers
Solid Particles
Temperature and Pressure:
Salts and Chemicals

Types of Emulsions

Water-in-Oil (W/O): Most common in crude oil systems, where water droplets are dispersed in oil.
Oil-in-Water (O/W): Less common, where oil droplets are dispersed in water.
Multiple Emulsions: Complex systems like water-in-oil-in-water (W/O/W).

Emulsion Break Challenges

Emulsion Breaker Product Selection and Treatment Philosophy

The stability of an emulsion depends on a number of factors, including:

» Type and concentration of emulsifying agent(s)

» Oil and water composition

» Viscosity of the fluids

» Density of the oil and water

» Amount and size of water droplets

» Age of the emulsion

» System temperature

130 Non-Ionic EO PO Block Copolymer Demulsifiers

I. The Nature and Formation Mechanism of Emulsion Aging

1. Physicochemical Changes During Aging

Initial Emulsion	Water droplets disperse in the oil phase, with natural emulsifiers (asphaltenes, resins, solid particles) adsorbed at the interface	Light brown color, good fluidity
Aging Phase	Interfacial film reorganization:	Emulsion layer thickens, darkens (brown-black)
	- Asphaltenes/resins undergo crosslinking/polymerization
	- Solid particles (clay, iron sulfide) deposit at the interface
Advanced Aging	Formation of a 3D network:	Emulsion viscosity surges, becomes paste-like
	- Interfacial film rigidity increases
	- Resistance to droplet coalescence rises

2. Factors Accelerating Aging

Time: Longer storage (>72 hours) worsens aging.

Temperature: High temperatures (>60°C) accelerate asphaltene oxidation/crosslinking.

Shear history: Mechanical shear from pumping/piping reduces droplet size, increasing interfacial area.

Oxygen exposure: Oxidation generates polar compounds (e.g., carboxylic acids), strengthening the interfacial film.

II. Four Major Impacts of Emulsion Aging on Demulsification

1. Interfacial Film Strengthening

*Young emulsions: Loose asphaltene films easily displaced by demulsifiers.

*Aged emulsions:

Asphaltenes form rigid π-π stacked films.

Solid particles (e.g., nano-clay) embed into films, creating an "armor effect."

→ Demulsifiers struggle to penetrate, requiring higher doses or stronger components.

2. Impaired Droplet Coalescence Kinetics

*Aging increases Zeta potential absolute values (from -30mV → -50mV), enhancing electrostatic repulsion.

*Elevated interfacial viscoelastic modulus (G') inhibits droplet collision/coalescence.

→ Demulsification time extends by 50–200% (empirical data).

3. Changes in Emulsion Stability

Parameter	Young Emulsion	Aged Emulsion	Demulsification Challenge
Droplet size	10–50 μm	1–10 μm	Smaller droplets resist coalescence.
Interfacial tension	15–20 mN/m	5–10 mN/m	Reduced demulsifier adsorption efficiency.
Viscoelastic modulus G'	0.1–1 Pa	10–100 Pa	Higher shear required to break films.

4. Demulsifier Efficacy Decline
*Oxidized products (e.g., quinones) in aged emulsions consume active demulsifier components.
*Rigid films demand demulsifiers with:

Higher molecular weight (>10,000 Da) to counter film strength.

Enhanced wettability (HLB 8–12) to displace solid particles.

III. Demulsification Strategies for Aged Emulsions

1. Demulsifier Formulation Optimization

Aging Level	Key Design Principles	Typical Formulation
Mild aging	Increase block copolymer ratio (e.g., EO-PO-EO).	Polyether-based + alcohol ether solvents.
Moderate aging	Add interfacial modifiers (e.g., alkylphenol resins) to penetrate solid particle layers.	Resin-modified polyether + butoxyethanol.
Severe aging	Blend strong penetrants (e.g., diethylene glycol monobutyl ether) to disrupt crosslinked networks.	Dendritic polymers + aromatic solvents.

2. Process Parameter Adjustments

Temperature: Increase to 80–90°C for severe aging (vs. 60°C for young emulsions).
Shear mixing: Use static mixers to apply moderate shear (50–100 s⁻¹) for film rupture.
Settling time: Extend to 120 minutes (vs. 30 minutes for young emulsions).

3. Pretreatment Technologies

Ultrasonic demulsification: 20–40 kHz ultrasound disrupts aged films (effective for paste-like sludge).
Electrochemical demulsification: High-voltage DC fields (15–30 kV/cm) neutralize Zeta potential.
Membrane separation: Ceramic ultrafiltration (0.1 μm) removes micro-droplets directly

IV. Industrial Case Comparison

Demulsification performance for emulsions of varying ages in a Bohai Sea oilfield:

Metric	Young Emulsion (<24h)	Aged Emulsion (30 days)	Solution Implemented
Demulsifier dosage	50 ppm	200 ppm	Dendritic polymer demulsifier.
Dehydration temperature	65℃	85℃	Upgraded heat exchanger.
Effluent oil content	<200 ppm	Initially >1000 ppm	Added electrostatic coalescer.
Desalted crude salt content	<5 PTB	Initially >20 PTB	Two-stage desalting process.

Based on the results and observations from the initial screening tests, the best performing intermediate chemistries are then blended in varying ratios and further tested to refine treatment performance and to identify the optimal treatment dose rate (ppm) required to achieve the necessary oil export specifications.

Emulsion aging = Interfacial film strengthening + droplet refinement + stability alteration over time.

Demulsification challenges: Rigid films, electrostatic repulsion, demulsifier depletion.

Solutions:

Tailor demulsifiers (MW/HLB/penetration) to aging stage.

Combine heat-shear-time process adjustments.

Deploy physical aids (ultrasound/electrochemistry).

YouzhuCHEM provides both O/W and W/O emulsion breakers, our demulsifier chemicals have been applied to Shengli Oilfield. Sichuan Oilfield, Also we provide the solutions to the Mid-Asias.
Contact us to get samples for your field trial, which is required to evaluate the performance of the newly developed commercial demulsifier product in the dynamic production system and to determine the optimal treatment dosage (ppm) to ensure the treated crude oil meets the required export specifications.