Flow Assurance in NeqSim

Flow assurance is the discipline ensuring that hydrocarbon fluids can be produced, transported, and processed safely and economically throughout the life of a field. NeqSim provides comprehensive tools for predicting and managing flow assurance challenges.

Overview

Flow assurance encompasses the prevention and remediation of:

• Hydrate formation - Ice-like structures that can block pipelines
• Wax deposition - Paraffin precipitation at low temperatures
• Asphaltene precipitation - Heavy organic precipitation during pressure/temperature changes
• Scale formation - Mineral deposits from produced water
• Corrosion - Material degradation from H₂S, CO₂, and water
• Slugging - Unstable multiphase flow regimes

Documentation Structure

Topic	Description
Asphaltene Modeling	Overview of asphaltene stability analysis
CPA-Based Asphaltene Calculations	Thermodynamic onset pressure/temperature
De Boer Asphaltene Screening	Empirical screening correlation
Asphaltene Parameter Fitting	Tuning CPA parameters to experimental data
Asphaltene Method Comparison	Comparing CPA vs De Boer approaches
Asphaltene Model Validation	Validation against SPE-24987 field data

Key Classes

Asphaltene Analysis

Class	Package	Purpose
AsphalteneCharacterization	neqsim.thermo.characterization	SARA-based characterization
AsphalteneStabilityAnalyzer	neqsim.pvtsimulation.flowassurance	High-level CPA analysis API
DeBoerAsphalteneScreening	neqsim.pvtsimulation.flowassurance	Empirical De Boer screening
AsphalteneMethodComparison	neqsim.pvtsimulation.flowassurance	Compare multiple methods
AsphalteneOnsetPressureFlash	neqsim.thermodynamicoperations	Onset pressure calculation
AsphalteneOnsetTemperatureFlash	neqsim.thermodynamicoperations	Onset temperature calculation
AsphalteneOnsetFitting	neqsim.pvtsimulation.util.parameterfitting	Fit CPA parameters to experimental onset data
AsphalteneOnsetFunction	neqsim.pvtsimulation.util.parameterfitting	Levenberg-Marquardt function for fitting

Quick Start

Simple Screening (De Boer Method)

import neqsim.pvtsimulation.flowassurance.DeBoerAsphalteneScreening;

// Create screening for specific conditions
DeBoerAsphalteneScreening screening = new DeBoerAsphalteneScreening(
    350.0,  // Reservoir pressure [bar]
    150.0,  // Bubble point pressure [bar]
    750.0   // In-situ oil density [kg/m³]
);

// Get risk assessment
String risk = screening.evaluateRisk();
double riskIndex = screening.calculateRiskIndex();

System.out.println("Asphaltene Risk: " + risk);
System.out.println("Risk Index: " + riskIndex);

Thermodynamic Analysis (CPA Method)

import neqsim.thermo.system.SystemSrkCPAstatoil;
import neqsim.thermodynamicoperations.ThermodynamicOperations;

// Create CPA fluid with asphaltene
SystemSrkCPAstatoil fluid = new SystemSrkCPAstatoil(373.15, 200.0);
fluid.addComponent("methane", 0.5);
fluid.addComponent("n-heptane", 0.45);
fluid.addComponent("asphaltene", 0.05);
fluid.setMixingRule("classic");

// Calculate onset pressure
ThermodynamicOperations ops = new ThermodynamicOperations(fluid);
ops.asphalteneOnsetPressure();

double onsetPressure = fluid.getPressure();
System.out.println("Onset Pressure: " + onsetPressure + " bar");

Parameter Fitting (Tuning to Lab Data)

import neqsim.pvtsimulation.util.parameterfitting.AsphalteneOnsetFitting;

// Create fitter with your fluid system
AsphalteneOnsetFitting fitter = new AsphalteneOnsetFitting(fluid);

// Add experimental onset points (T in Kelvin, P in bar)
fitter.addOnsetPoint(353.15, 350.0);  // 80°C
fitter.addOnsetPoint(373.15, 320.0);  // 100°C
fitter.addOnsetPoint(393.15, 280.0);  // 120°C

// Set initial parameter guesses and run fitting
fitter.setInitialGuess(3500.0, 0.005);  // epsilon/R, kappa
fitter.solve();

// Get fitted CPA parameters
double epsilonR = fitter.getFittedAssociationEnergy();
double kappa = fitter.getFittedAssociationVolume();

Asphaltene Component in NeqSim Database

NeqSim includes a pre-defined asphaltene pseudo-component with CPA parameters suitable for typical asphaltene modeling:

Property	Value	Unit
Molecular Weight	750	g/mol
Critical Temperature	1049.85	K
Critical Pressure	8.0	bar
Acentric Factor	1.5	-
Association Energy (ε/R)	3500	K
Association Volume (κ)	0.005	-

These parameters can be tuned to match specific experimental data using the AsphalteneOnsetFitting class.

PhaseType.ASPHALTENE

When asphaltene precipitates, NeqSim identifies it using the dedicated PhaseType.ASPHALTENE enum value. This enables:

• Accurate phase identification - Distinguish asphaltene from wax or hydrate
• Correct physical properties - Asphaltene-specific density (~1150 kg/m³), viscosity (~10,000 Pa·s), thermal conductivity (~0.20 W/mK)
• Easy API access - Use fluid.hasPhaseType("asphaltene") to detect precipitation

import neqsim.thermo.phase.PhaseType;

// After flash calculation
if (fluid.hasPhaseType(PhaseType.ASPHALTENE)) {
    PhaseInterface asphaltene = fluid.getPhaseOfType("asphaltene");
    System.out.println("Asphaltene density: " + asphaltene.getDensity("kg/m3") + " kg/m³");
    System.out.println("Asphaltene fraction: " + (asphaltene.getBeta() * 100) + "%");
}

See Asphaltene Modeling for more details on PhaseType.ASPHALTENE.

Related Topics

• Thermodynamic Models - Equation of state fundamentals
• PVT Simulation - Fluid characterization
• Process Equipment - Separator and pipeline modeling