Whitson PVT Parameter File Reader

The WhitsonPVTReader class enables NeqSim to read PVT parameter files exported from Whitson+ and similar PVT software, creating fully configured fluid systems with accurate thermodynamic properties.

Overview

When working with PVT characterization software like Whitson+, you can export equation of state parameters and component properties to a tab-separated file format. The WhitsonPVTReader parses these files and creates NeqSim SystemInterface objects with:

File Format

The Whitson PVT parameter file is a tab-separated text file with three main sections:

1. Parameters Section

Key-value pairs defining global EOS and model parameters:

Parameter	Value
Name	Predictive_EOS_Parameters
EOS Type	PR
LBC P0	0.1023
LBC P1	0.023364
LBC P2	0.058533
LBC P3	-0.037734245
LBC P4	0.00839916
LBC F0	0.1
C7+ Gamma Shape	0.677652
C7+ Gamma Bound	94.9981
Omega A, ΩA	0.457236
Omega B, ΩB	0.0777961

2. Component Table

Component properties with a header row and units row:

Component	MW	Pc	Tc	AF, ω	Volume Shift, s	ZcVisc	VcVisc	Vc	Zc	Pchor	SG	Tb	LMW
-	-	bara	C	-	-	-	m3/kmol	m3/kmol	-	-	-	C	-
CO2	44.01000	73.74000	30.97000	0.225000	0.001910	0.274330	0.09407	0.09407	0.274330	80.00	0.76193	-88.266	
N2	28.01400	33.98000	-146.95000	0.037000	-0.167580	0.291780	0.09010	0.09010	0.291780	59.10	0.28339	-195.903	
C1	16.04300	45.99000	-82.59000	0.011000	-0.149960	0.286200	0.09860	0.09860	0.286200	71.00	0.14609	-161.593	
...

Column definitions: | Column | Description | Units | |——–|————-|——-| | Component | Component name | - | | MW | Molecular weight | g/mol | | Pc | Critical pressure | bara | | Tc | Critical temperature | °C | | AF, ω | Acentric factor | - | | Volume Shift, s | Peneloux volume shift | - | | ZcVisc | Critical compressibility for viscosity | - | | VcVisc | Critical volume for viscosity | m³/kmol | | Vc | Critical volume | m³/kmol | | Zc | Critical compressibility | - | | Pchor | Parachor | - | | SG | Specific gravity | - | | Tb | Normal boiling point | °C | | LMW | Lumped molecular weight (optional) | g/mol |

3. Binary Interaction Parameters (BIPs)

Full symmetric matrix of binary interaction parameters:

BIPS	CO2	N2	C1	C2	C3	...
CO2	0.00	0.00	0.11	0.13	0.13	...
N2	0.00	0.00	0.03	0.01	0.09	...
C1	0.11	0.03	0.00	0.00	0.00	...
...

Usage Examples

Basic Usage

Read a parameter file and create a fluid with equal molar composition:

import neqsim.thermo.util.readwrite.WhitsonPVTReader;
import neqsim.thermo.system.SystemInterface;

// Read parameter file
SystemInterface fluid = WhitsonPVTReader.read("path/to/volveparam.txt");

// Set conditions
fluid.setTemperature(373.15);  // 100°C in Kelvin
fluid.setPressure(200.0);       // 200 bar

// Run flash calculation
ThermodynamicOperations ops = new ThermodynamicOperations(fluid);
ops.TPflash();

// Get properties
double density = fluid.getDensity("kg/m3");
double viscosity = fluid.getViscosity("cP");

With Custom Composition

Specify molar composition matching the component order in the file:

// Define composition (must match number of components in file)
double[] composition = {
    0.02,   // CO2
    0.01,   // N2
    0.70,   // C1
    0.10,   // C2
    0.05,   // C3
    0.08,   // C7
    0.04    // C10
};

SystemInterface fluid = WhitsonPVTReader.read("path/to/volveparam.txt", composition);

Accessing Parsed Parameters

The reader provides getters for extracted parameters:

WhitsonPVTReader reader = new WhitsonPVTReader();
reader.parseFile("path/to/volveparam.txt");

// Get LBC viscosity parameters
double[] lbcParams = reader.getLBCParameters();
// Returns: [P0, P1, P2, P3, P4, F0]

// Get C7+ gamma distribution parameters
double[] gammaParams = reader.getGammaParameters();
// Returns: [shape, bound]

// Get Omega parameters
double omegaA = reader.getOmegaA();
double omegaB = reader.getOmegaB();

// Get component information
int numComponents = reader.getNumberOfComponents();
List<String> names = reader.getComponentNames();

Component Name Mapping

The reader automatically maps Whitson component names to NeqSim standard names:

Whitson Name NeqSim Name
C1 methane
C2 ethane
C3 propane
i-C4 i-butane
n-C4 n-butane
i-C5 i-pentane
n-C5 n-pentane
NEO-C5 22-dim-C3
C6 n-hexane
N2 nitrogen
CO2 CO2
H2S H2S
H2O water

C7+ fractions (C7, C8, C9, …, C36+) are added as pseudo-components with the suffix _PC.

Supported EOS Types

File Value NeqSim Class
PR SystemPrEos
SRK SystemSrkEos
PR78 SystemPrEos1978

Integration with Whitson+ Workflows

This reader enables seamless integration between Whitson+ PVT characterization and NeqSim process simulation:

  1. PVT Characterization: Use Whitson+ to fit EOS parameters to laboratory data (CCE, CVD, DLE, separator tests)
  2. Parameter Export: Export the fitted parameters to a tab-separated file
  3. NeqSim Import: Use WhitsonPVTReader to create a NeqSim fluid
  4. Process Simulation: Use the characterized fluid in NeqSim process simulations

This workflow ensures consistency between PVT modeling and process simulation, using the same EOS parameters throughout.

PVT Simulations with Imported Fluids

Once a fluid is created from a Whitson file, you can run standard PVT simulations:

import neqsim.pvtsimulation.simulation.*;
import neqsim.pvtsimulation.util.PVTReportGenerator;

// Create fluid from Whitson file
double[] composition = {0.02, 0.01, 0.70, 0.10, 0.05, 0.08, 0.04};
SystemInterface fluid = WhitsonPVTReader.read("volveparam.txt", composition);

// Initialize
fluid.setTemperature(373.15);  // 100°C
fluid.setPressure(300.0);
ThermodynamicOperations ops = new ThermodynamicOperations(fluid);
ops.TPflash();
fluid.initPhysicalProperties();

// Saturation pressure (dew point for gas condensate)
SaturationPressure satPres = new SaturationPressure(fluid);
satPres.setTemperature(100.0, "C");
satPres.run();
double psat = satPres.getSaturationPressure();

// Constant Composition Expansion (CCE)
ConstantMassExpansion cce = new ConstantMassExpansion(fluid);
cce.setTemperature(100.0, "C");
cce.setPressures(new double[]{300, 250, 200, 150, 100});
cce.runCalc();
double[] relVol = cce.getRelativeVolume();

// Multi-Stage Separator Test
MultiStageSeparatorTest sepTest = new MultiStageSeparatorTest(fluid);
sepTest.setReservoirConditions(300.0, 100.0);
sepTest.addSeparatorStage(50.0, 40.0, "HP Separator");
sepTest.addSeparatorStage(10.0, 30.0, "LP Separator");
sepTest.addSeparatorStage(1.01325, 15.0, "Stock Tank");
sepTest.run();

double gor = sepTest.getTotalGOR();        // Sm³/Sm³
double bo = sepTest.getBo();               // m³/Sm³
double apiGravity = sepTest.getStockTankAPIGravity();
double stockTankDensity = sepTest.getStockTankOilDensity();  // kg/m³

// Get oil properties at each separator stage
for (var stage : sepTest.getStageResults()) {
    double oilDensity = stage.getOilDensity();     // kg/m³
    double oilViscosity = stage.getOilViscosity(); // cP
}

// Generate PVT Report
PVTReportGenerator report = new PVTReportGenerator(fluid);
report.setProjectInfo("My Project", "Gas Condensate Sample")
      .setReservoirConditions(300.0, 100.0)
      .setSaturationPressure(psat, false)  // false = dew point
      .addCCE(cce)
      .addSeparatorTest(sepTest);

String markdownReport = report.generateMarkdownReport();
System.out.println(markdownReport);

LBC Viscosity Model

The reader automatically applies the LBC viscosity model with the parameters from the Whitson file (P0-P4). The viscosity is calculated using:

// Viscosity is automatically calculated with LBC model
fluid.initPhysicalProperties();

// Gas phase viscosity
double gasViscosity = fluid.getPhase("gas").getPhysicalProperties().getViscosity();
double gasViscosityCP = gasViscosity * 1000;  // Convert Pa·s to cP

// Oil phase viscosity (if oil phase exists)
if (fluid.hasPhaseType("oil")) {
    double oilViscosity = fluid.getPhase("oil").getPhysicalProperties().getViscosity();
    double oilViscosityCP = oilViscosity * 1000;  // Convert Pa·s to cP
}

You can also use ViscositySim to calculate viscosity at multiple pressures:

import neqsim.pvtsimulation.simulation.ViscositySim;

ViscositySim viscSim = new ViscositySim(fluid);
double[] pressures = {300.0, 250.0, 200.0, 150.0, 100.0};
double[] temperatures = new double[pressures.length];
Arrays.fill(temperatures, 373.15);  // 100°C in Kelvin
viscSim.setTemperaturesAndPressures(temperatures, pressures);
viscSim.runCalc();

double[] gasViscosity = viscSim.getGasViscosity();   // Pa·s (multiply by 1000 for cP)
double[] oilViscosity = viscSim.getOilViscosity();   // Pa·s (multiply by 1000 for cP)

Example Output

A typical PVT report for a gas condensate fluid created from a Whitson parameter file:

# PVT Study Report

## Project Information

| Property | Value |
|----------|-------|
| Project | Whitson PVT Reader Test |
| Fluid Name | Test Gas Condensate |
| Report Date | 2025-12-15 12:59 |

## Reservoir Conditions

| Property | Value | Unit |
|----------|-------|------|
| Reservoir Pressure | 300.0 | bara |
| Reservoir Temperature | 100.0 | °C |
| Dew Point Pressure | 248.41 | bara |

## Fluid Composition

| Component | Mole Fraction | MW (g/mol) |
|-----------|--------------|------------|
| CO2 | 0.020000 | 44.01 |
| nitrogen | 0.010000 | 28.01 |
| methane | 0.700000 | 16.04 |
| ethane | 0.100000 | 30.07 |
| propane | 0.050000 | 44.10 |
| C7_PC | 0.080000 | 97.63 |
| C10_PC | 0.040000 | 134.47 |

## Constant Composition Expansion (CCE)

| Pressure (bara) | Rel. Volume | Y-Factor | Density (kg/m³) |
|-----------------|-------------|----------|-----------------|
| 298.1 | 0.8332 | - | 332.0 |
| 273.2 | 0.8703 | - | 318.3 |
| 248.4 | 0.9163 | - | 302.8 |
| 223.6 | 1.0042 | 1.1212 | 234.5 |
| 198.7 | 1.1188 | 1.0966 | 193.6 |
| 173.9 | 1.2725 | 1.0707 | 160.5 |

## Separator Test

=== Multi-Stage Separator Test Results ===

Reservoir Conditions: P = 300.0 bara, T = 100.0 °C
Number of Stages: 3

Stage-by-Stage Results:
| Stage | P (bara) | T (°C) | GOR (Sm³/Sm³) | Cum GOR (Sm³/Sm³) |
|-------|----------|--------|---------------|-------------------|
| HP Separator | 50.0 | 40.0 | 1096.9 | 1096.9 |
| LP Separator | 10.0 | 30.0 | 53.9 | 1150.8 |
| Stock Tank | 1.0 | 15.0 | 23.6 | 1174.4 |

Overall Results:
  Total GOR:           1174.4 Sm³/Sm³
  Bo (FVF):            5.0880 rm³/Sm³
  Stock Tank Density:  751.5 kg/m³
  API Gravity:         56.6 °API

## Quality Metrics

---
*Report generated by NeqSim PVT Report Generator*

Additional PVT Data

Gas Viscosity (LBC Model)

Pressure (bara) Viscosity (cP)
300.0 0.0387
250.0 0.0340
200.0 0.0227
150.0 0.0178
100.0 0.0151

Gas Density

Pressure (bara) Density (kg/m³)
300.0 333.04
250.0 303.87
200.0 195.47
150.0 132.69
100.0 82.11

Separator Stage Oil Properties

Stage P (bara) T (°C) Oil Density (kg/m³) Oil Viscosity (cP)
HP Separator 50.0 40.0 - 0.6315
LP Separator 10.0 30.0 675.35 0.6143
Stock Tank 1.0 15.0 723.65 0.6643

Oil Properties vs Pressure

For gas condensates, an oil (condensate) phase forms below the dew point pressure. The properties are:

Pressure (bara) Density (kg/m³) Viscosity (cP)
200.0 482.81 0.0666
150.0 544.85 0.0903

Note: Oil phase only exists below the dew point pressure (248.4 bara for this fluid).

Gas Condensate Metrics Summary

Property Value Unit
Dew Point Pressure 248.41 bara
GOR 1174.4 Sm³/Sm³
CGR 5.4 bbl/MMscf
Bo 5.0880 m³/Sm³
Stock Tank API 56.6 °API
Stock Tank Density 751.5 kg/m³
Molar Mass 30.79 g/mol

See Also