Emulsion Viscosity Calculator

The EmulsionViscosityCalculator predicts the effective viscosity of oil-water emulsions using six established correlations and includes automatic phase inversion detection.

Class: neqsim.pvtsimulation.flowassurance.EmulsionViscosityCalculator

Why Emulsion Viscosity Matters

In multiphase oil-water production:

Available Models

Model Formula Best For
Einstein $\mu_r = 1 + 2.5\phi$ Dilute systems ($\phi < 0.05$)
Taylor Includes dispersed phase viscosity ratio Low-moderate concentration
Brinkman $\mu_r = (1 - \phi)^{-2.5}$ Moderate concentration
Pal-Rhodes Accounts for packing fraction General purpose (default)
Woelflin Empirical with tightness factor Field emulsions
Richardson Exponential model Heavy oils

Where $\mu_r$ is relative viscosity and $\phi$ is dispersed phase volume fraction.

Phase Inversion

The calculator automatically detects phase inversion using the Arirachakaran correlation:

\[f_{inv} = \frac{1}{1 + \left(\frac{\mu_o}{\mu_w}\right)^{0.25} \left(\frac{\rho_w}{\rho_o}\right)^{0.5}}\]

The inversion is adjusted by the tightness factor (emulsifier/surfactant effect).

Usage

Basic Calculation

import neqsim.pvtsimulation.flowassurance.EmulsionViscosityCalculator;

EmulsionViscosityCalculator calc = new EmulsionViscosityCalculator();
calc.setOilViscosity(20.0);      // mPa.s (cP)
calc.setWaterViscosity(0.8);     // mPa.s (cP)
calc.setOilDensity(850.0);       // kg/m3
calc.setWaterDensity(1020.0);    // kg/m3
calc.setWaterCut(0.30);          // 30% water cut
calc.setModel("pal_rhodes");     // Default model
calc.calculate();

double effectiveVisc = calc.getEffectiveViscosity(); // mPa.s
double relativeVisc = calc.getRelativeViscosity();   // dimensionless
String emulsionType = calc.getEmulsionType();        // "W/O" or "O/W"
double inversionPt = calc.getInversionWaterCut();    // volume fraction

System.out.printf("Effective viscosity: %.2f cP%n", effectiveVisc);
System.out.printf("Relative viscosity: %.2f%n", relativeVisc);
System.out.printf("Emulsion type: %s%n", emulsionType);
System.out.printf("Inversion point: %.1f%% WC%n", inversionPt * 100);

Comparing Models

String[] models = {"einstein", "taylor", "brinkman", "pal_rhodes", "woelflin", "richardson"};

EmulsionViscosityCalculator calc = new EmulsionViscosityCalculator();
calc.setOilViscosity(15.0);
calc.setWaterViscosity(1.0);
calc.setOilDensity(860.0);
calc.setWaterDensity(1020.0);
calc.setWaterCut(0.25);

for (String model : models) {
    calc.setModel(model);
    calc.calculate();
    System.out.printf("%-12s  mu=%.2f cP  mu_r=%.3f%n",
        model, calc.getEffectiveViscosity(), calc.getRelativeViscosity());
}

Viscosity vs Water Cut Curve

Generate data for plotting viscosity as a function of water cut:

EmulsionViscosityCalculator calc = new EmulsionViscosityCalculator();
calc.setOilViscosity(20.0);
calc.setWaterViscosity(1.0);
calc.setOilDensity(850.0);
calc.setWaterDensity(1020.0);
calc.setModel("pal_rhodes");

// Generate curve from 0% to 80% water cut, 50 points
double[][] curve = calc.calculateViscosityCurve(0.0, 0.80, 50);

System.out.println("WaterCut  Viscosity_cP");
for (double[] point : curve) {
    System.out.printf("%.3f     %.2f%n", point[0], point[1]);
}

The curve typically shows:

  1. Gradual increase in viscosity as water cut rises (W/O region)
  2. Peak near the phase inversion point
  3. Drop to lower values in the O/W region

Demulsifier Effect

calc.setWaterCut(0.35);
calc.calculate();
double withoutDemulsifier = calc.getEffectiveViscosity();

calc.setDemulsifierPresent(true);
calc.setDemulsifierEfficiency(0.6); // 0-1 scale
calc.calculate();
double withDemulsifier = calc.getEffectiveViscosity();

System.out.printf("Without demulsifier: %.2f cP%n", withoutDemulsifier);
System.out.printf("With demulsifier:    %.2f cP%n", withDemulsifier);
System.out.printf("Reduction: %.0f%%%n",
    (1.0 - withDemulsifier / withoutDemulsifier) * 100);

Emulsion Tightness

The tightness factor models how strongly the emulsion resists coalescence:

calc.setTightnessFactor(0.2);  // Loose emulsion (easy to break)
calc.calculate();
double loose = calc.getEffectiveViscosity();

calc.setTightnessFactor(0.8);  // Tight emulsion (hard to break)
calc.calculate();
double tight = calc.getEffectiveViscosity();

Tight emulsions (high surfactant, asphaltene, or fine solid content) have higher effective viscosity and shift the inversion point to higher water cuts.

Input Parameters

Parameter Method Unit Default
Oil viscosity setOilViscosity() mPa.s (cP) 10.0
Water viscosity setWaterViscosity() mPa.s (cP) 1.0
Oil density setOilDensity() kg/m3 850.0
Water density setWaterDensity() kg/m3 1020.0
Water cut setWaterCut() fraction (0-1) 0.0
Temperature setTemperatureC() °C 60.0
Pressure setPressureBara() bara 10.0
Model setModel() string "pal_rhodes"
Max packing fraction setMaxPackingFraction() fraction 0.74
Tightness factor setTightnessFactor() 0-1 0.5
Demulsifier present setDemulsifierPresent() boolean false
Demulsifier efficiency setDemulsifierEfficiency() 0-1 0.0

Output Values

Result Method Unit
Effective viscosity getEffectiveViscosity() mPa.s (cP)
Relative viscosity getRelativeViscosity() dimensionless
Viscosity ratio getViscosityRatio() dimensionless
Emulsion type getEmulsionType() “W/O” or “O/W”
Phase inverted? isInverted() boolean
Inversion water cut getInversionWaterCut() fraction

JSON Output

calc.calculate();
String json = calc.toJson();

Returns a JSON object with:

Python Usage

from neqsim import jneqsim

EmulsionViscosityCalculator = jneqsim.pvtsimulation.flowassurance.EmulsionViscosityCalculator

calc = EmulsionViscosityCalculator()
calc.setOilViscosity(20.0)
calc.setWaterViscosity(1.0)
calc.setOilDensity(850.0)
calc.setWaterDensity(1020.0)
calc.setWaterCut(0.30)
calc.setModel("pal_rhodes")
calc.calculate()

print(f"Effective viscosity: {calc.getEffectiveViscosity():.2f} cP")
print(f"Emulsion type: {calc.getEmulsionType()}")
print(f"Inversion point: {calc.getInversionWaterCut()*100:.1f}% WC")

# Generate viscosity curve
curve = calc.calculateViscosityCurve(0.0, 0.8, 50)
for i in range(len(curve)):
    print(f"WC={curve[i][0]:.2f}  mu={curve[i][1]:.2f} cP")

Model Selection Guide

Scenario Recommended Model
Quick screening brinkman
General production pal_rhodes (default)
Heavy oil, high water cut woelflin with tightness factor
Dilute emulsions (< 5% WC) einstein
Detailed study Compare all models