Black Oil PVT and Reservoir Simulator Export

This document describes NeqSim’s black oil implementation and the ability to export PVT data to reservoir simulators like Eclipse and CMG.

Overview

NeqSim provides a complete workflow for converting compositional EOS (Equation of State) fluid models to black oil PVT tables suitable for reservoir simulation. The neqsim.blackoil package includes:

BlackOilConverter - Converts compositional fluids to black oil properties
BlackOilPVTTable - Stores black oil PVT data (Bo, Rs, Bg, μo, μg, etc.)
EclipseEOSExporter - Exports to Schlumberger Eclipse format
CMGEOSExporter - Exports to CMG IMEX/GEM/STARS formats

Black Oil Conversion

The BlackOilConverter class performs flash calculations at multiple pressures to generate black oil properties:

import neqsim.blackoil.BlackOilConverter;
import neqsim.blackoil.BlackOilPVTTable;
import neqsim.thermo.system.SystemInterface;
import neqsim.thermo.system.SystemSrkEos;

// Create a compositional fluid
SystemInterface fluid = new SystemSrkEos(373.15, 200.0); // 100°C, 200 bar
fluid.addComponent("nitrogen", 0.01);
fluid.addComponent("CO2", 0.02);
fluid.addComponent("methane", 0.50);
fluid.addComponent("ethane", 0.08);
fluid.addComponent("propane", 0.05);
fluid.addComponent("n-butane", 0.03);
fluid.addComponent("n-pentane", 0.02);
fluid.addComponent("n-hexane", 0.02);
fluid.addComponent("n-heptane", 0.07);
fluid.addComponent("water", 0.20);
fluid.setMixingRule("classic");

// Define pressure grid for PVT table
double[] pressures = {20, 50, 100, 150, 200, 250, 300, 350, 400}; // bar

// Convert to black oil
double Tref = 373.15;  // Reference temperature (K)
double Pstd = 1.01325; // Standard pressure (bar)
double Tstd = 288.15;  // Standard temperature (K)

BlackOilPVTTable pvtTable = BlackOilConverter.convert(fluid, Tref, pressures, Pstd, Tstd);

Black Oil Properties

The BlackOilPVTTable contains records with the following properties:

Property	Symbol	Unit	Description
Pressure	p	bar	Reservoir pressure
Solution GOR	Rs	Sm³/Sm³	Gas dissolved in oil at standard conditions
Oil FVF	Bo	Rm³/Sm³	Oil formation volume factor
Oil viscosity	μo	Pa·s	Oil dynamic viscosity
Gas FVF	Bg	Rm³/Sm³	Gas formation volume factor
Gas viscosity	μg	Pa·s	Gas dynamic viscosity
Vaporized OGR	Rv	Sm³/Sm³	Oil vaporized in gas (for volatile oil/gas condensate)
Water FVF	Bw	Rm³/Sm³	Water formation volume factor
Water viscosity	μw	Pa·s	Water dynamic viscosity

Eclipse Export

The EclipseEOSExporter generates PVT include files compatible with Schlumberger Eclipse reservoir simulator.

Basic Usage

import neqsim.blackoil.io.EclipseEOSExporter;
import java.nio.file.Path;

// Export with default settings (METRIC units)
EclipseEOSExporter.toFile(fluid, Path.of("PVT.INC"));

// Or get as string
String eclipseOutput = EclipseEOSExporter.toString(fluid);

Configuration Options

import neqsim.blackoil.io.EclipseEOSExporter;
import neqsim.blackoil.io.EclipseEOSExporter.ExportConfig;
import neqsim.blackoil.io.EclipseEOSExporter.Units;

ExportConfig config = new ExportConfig()
    .setUnits(Units.FIELD)                              // METRIC or FIELD
    .setIncludeHeader(true)                             // Include header comments
    .setComment("Generated for Field X, Well A-1")      // Custom comment
    .setPressureGrid(new double[]{50, 100, 150, 200, 250, 300, 350, 400})
    .setIncludePVTO(true)                               // Include live oil table
    .setIncludePVTG(true)                               // Include wet gas table
    .setIncludePVTW(true)                               // Include water properties
    .setIncludeDensity(true);                           // Include DENSITY keyword

String output = EclipseEOSExporter.toString(fluid, config);

Export from Pre-computed PVT Table

// If you already have a BlackOilPVTTable
double rhoOilSc = 820.0;   // Oil density at standard conditions (kg/m³)
double rhoGasSc = 1.2;     // Gas density at standard conditions (kg/m³)
double rhoWaterSc = 1000.0; // Water density at standard conditions (kg/m³)

EclipseEOSExporter.toFile(pvtTable, rhoOilSc, rhoGasSc, rhoWaterSc, Path.of("PVT.INC"));

Eclipse Output Format

The exporter generates the following Eclipse keywords:

DENSITY

DENSITY
-- Oil      Gas       Water
   820.0    1.200000  1000.0 /

PVTO (Live Oil)

PVTO
-- Rs       P         Bo        mu_o
   50.0     100.0     1.250     0.00080
            150.0     1.220     0.00085
            200.0     1.200     0.00090 /
   80.0     150.0     1.350     0.00070
            200.0     1.320     0.00075 /
/

PVTG (Wet Gas)

PVTG
-- Pg       Rv        Bg        mu_g
   100.0    0.0       0.0120    1.50E-05
            0.0001    0.0122    1.52E-05 /
   150.0    0.0       0.0080    1.80E-05 /
/

PVTW (Water)

PVTW
-- Pref     Bw        Cw        mu_w    Cv
   200.0    1.020     4.5E-05   0.00050 0.0 /

Unit Systems

Property	METRIC	FIELD
Pressure	bar (BARSA)	psia (PSIA)
Density	kg/m³	lb/ft³
FVF	rm³/sm³	rb/stb
GOR	sm³/sm³	scf/stb
Viscosity	cP	cP

CMG Export

The CMGEOSExporter generates PVT data files compatible with CMG reservoir simulators (IMEX, GEM, STARS).

Basic Usage

import neqsim.blackoil.io.CMGEOSExporter;
import java.nio.file.Path;

// Export with default settings (IMEX, SI units)
CMGEOSExporter.toFile(fluid, Path.of("PVT.DAT"));

// Or get as string
String cmgOutput = CMGEOSExporter.toString(fluid);

Configuration Options

import neqsim.blackoil.io.CMGEOSExporter;
import neqsim.blackoil.io.CMGEOSExporter.ExportConfig;
import neqsim.blackoil.io.CMGEOSExporter.Simulator;
import neqsim.blackoil.io.CMGEOSExporter.Units;

ExportConfig config = new ExportConfig()
    .setSimulator(Simulator.IMEX)                       // IMEX, GEM, or STARS
    .setUnits(Units.FIELD)                              // SI or FIELD
    .setModelName("RESERVOIR_FLUID_MODEL")              // Model identifier
    .setComment("PVT model for Field X")                // Custom comment
    .setPressureGrid(new double[]{50, 100, 150, 200, 250, 300});

CMGEOSExporter.toFile(fluid, Path.of("PVT.DAT"), config);

CMG Simulators

Simulator	Type	Description
IMEX	Black Oil	Implicit-Explicit black oil simulator
GEM	Compositional	Generalized equation-of-state model
STARS	Thermal	Steam, thermal, and advanced processes

IMEX Output Format

** ============================================================
** Generated by NeqSim - Black Oil PVT Export
** Simulator: IMEX
** Units: SI
** ============================================================

*MODEL *BLACKOIL

*DENSITY *OIL 820.0
*DENSITY *GAS 1.2
*DENSITY *WATER 1000.0

*BOTOIL
** P(kPa)    Rs(m3/m3)    Bo(m3/m3)    mu_o(cP)
   10000.0   50.0         1.250        0.80
   15000.0   80.0         1.350        0.70
   20000.0   100.0        1.420        0.65

*BOTGAS
** P(kPa)    Bg(m3/m3)    mu_g(cP)
   10000.0   0.0120       0.015
   15000.0   0.0080       0.018
   20000.0   0.0060       0.021

Unit Systems

Property	SI	FIELD
Pressure	kPa	psia
Density	kg/m³	lb/ft³
FVF	m³/m³	bbl/bbl
GOR	m³/m³	scf/bbl
Viscosity	cP	cP

Complete Workflow Example

import neqsim.blackoil.BlackOilConverter;
import neqsim.blackoil.BlackOilPVTTable;
import neqsim.blackoil.io.EclipseEOSExporter;
import neqsim.blackoil.io.CMGEOSExporter;
import neqsim.thermo.system.SystemSrkEos;
import java.nio.file.Path;

public class PVTExportExample {
    public static void main(String[] args) {
        // 1. Create compositional fluid model
        var fluid = new SystemSrkEos(373.15, 250.0);
        fluid.addComponent("methane", 0.60);
        fluid.addComponent("ethane", 0.08);
        fluid.addComponent("propane", 0.05);
        fluid.addComponent("n-butane", 0.03);
        fluid.addComponent("n-pentane", 0.02);
        fluid.addComponent("n-heptane", 0.12);
        fluid.addComponent("water", 0.10);
        fluid.setMixingRule("classic");
        
        // 2. Export to Eclipse (METRIC units)
        var eclipseConfig = new EclipseEOSExporter.ExportConfig()
            .setUnits(EclipseEOSExporter.Units.METRIC)
            .setComment("Light oil reservoir - Block A");
        EclipseEOSExporter.toFile(fluid, Path.of("eclipse_pvt.inc"), eclipseConfig);
        
        // 3. Export to CMG IMEX (FIELD units)
        var cmgConfig = new CMGEOSExporter.ExportConfig()
            .setSimulator(CMGEOSExporter.Simulator.IMEX)
            .setUnits(CMGEOSExporter.Units.FIELD)
            .setModelName("BLOCK_A_FLUID");
        CMGEOSExporter.toFile(fluid, Path.of("cmg_pvt.dat"), cmgConfig);
        
        System.out.println("PVT files exported successfully!");
    }
}

E300 Compositional EOS Export

In addition to black-oil PVT tables, NeqSim can export the full compositional EOS model to Eclipse E300 format. This is useful when you need to preserve all EOS parameters for compositional reservoir simulation.

E300 Format Background

The Eclipse E300 format is a proprietary format originated by Schlumberger for their Eclipse compositional reservoir simulator. While there is no public formal specification, the format is widely used and supported by:

Schlumberger Eclipse 300 - The original compositional simulator
OPM Flow - Open-source simulator with E300 compatibility (see OPM Reference Manual)
PVTsim Nova by Calsep - Commercial PVT software with E300 export
Other commercial simulators that read Eclipse-compatible files

The NeqSim E300 export is compatible with files generated by PVTsim Nova and produces output that can be read by Eclipse 300 and OPM Flow.

Basic Usage

import neqsim.thermo.util.readwrite.EclipseFluidReadWrite;

// Export fluid to E300 compositional format
EclipseFluidReadWrite.write(fluid, "RESERVOIR_FLUID.e300", 100.0);  // 100°C reservoir temp

// Get as string for inspection
String e300Content = EclipseFluidReadWrite.toE300String(fluid, 100.0);

E300 File Keywords

The exported E300 file contains all EOS parameters needed for compositional simulation:

Keyword	Description	Units
`METRIC`	Units system (always METRIC)	-
`NCOMPS`	Number of components	-
`EOS`	Equation of state type	SRK/PR
`PRCORR`	Peng-Robinson correction (for PR EOS only)	-
`RTEMP`	Reservoir temperature	°C
`STCOND`	Standard conditions	°C, bara
`CNAMES`	Component names	-
`TCRIT`	Critical temperatures	K
`PCRIT`	Critical pressures	bar
`ACF`	Acentric factors	-
`OMEGAA`	EOS parameter a (0.45724 for PR, 0.42748 for SRK)	-
`OMEGAB`	EOS parameter b (0.07780 for PR, 0.08664 for SRK)	-
`MW`	Molecular weights	g/mol
`TBOIL`	Normal boiling points	K
`VCRIT`	Critical volumes	m³/kmol
`ZCRIT`	Critical Z-factors	-
`SSHIFT`	Volume translation	-
`PARACHOR`	Parachor values	-
`ZI`	Mole fractions	-
`BIC`	Binary interaction coefficients	-

Round-Trip: Export and Import

import neqsim.thermo.util.readwrite.EclipseFluidReadWrite;
import neqsim.thermo.system.SystemInterface;
import neqsim.thermodynamicoperations.ThermodynamicOperations;

// Create and tune fluid
SystemInterface tunedFluid = /* ... your tuned fluid ... */;

// Export to E300 file
EclipseFluidReadWrite.write(tunedFluid, "TUNED.e300", 100.0);

// Read it back (e.g., in another session or application)
SystemInterface importedFluid = EclipseFluidReadWrite.read("TUNED.e300");

// Use the imported fluid
importedFluid.setPressure(200.0, "bara");
importedFluid.setTemperature(100.0, "C");
new ThermodynamicOperations(importedFluid).TPflash();

Optional E300 Keywords

Some E300 files include additional keywords that are handled by NeqSim:

Keyword	Description	Status in NeqSim
`BICS`	BIC at surface conditions	Supported (read and write)
`SSHIFTS`	Volume shift at surface conditions	Supported (read and write)
`LBCCOEF`	Lohrenz-Bray-Clark viscosity coefficients	Supported (read and write)
`PEDERSEN`	Pedersen viscosity correlation flag	Supported (read and write)

LBCCOEF Support

NeqSim supports reading and writing the LBCCOEF keyword for the Lohrenz-Bray-Clark (LBC) viscosity correlation:

LBCCOEF
0.1084806 -0.0295031 0.1130421 -0.0553108 0.0093324 /

When reading an E300 file with LBCCOEF:

NeqSim automatically applies the LBC viscosity model to all phases
The 5 coefficients are set as the dense contribution parameters

When writing an E300 file:

If the fluid uses the LBC viscosity model, the coefficients are exported

PEDERSEN Support

The PEDERSEN keyword is a flag indicating the Pedersen (PFCT) corresponding-states viscosity correlation:

PEDERSEN

When reading: NeqSim applies the PFCT viscosity model to all phases. When writing: If PFCT viscosity model is active, the PEDERSEN keyword is output.

BICS and SSHIFTS Support

BICS: Binary interaction coefficients at surface conditions (same format as BIC)
SSHIFTS: Volume translation at surface conditions (same format as SSHIFT)

These are written automatically when exporting E300 files.

Compatibility Notes

SRK vs PR: The EOS type is auto-detected from the fluid class name. Peng-Robinson fluids (SystemPrEos, etc.) export with PR and include the PRCORR keyword.
Component Names: Long component names are automatically shortened (e.g., “methane” → “C1”, “n-butane” → “C4”).
Binary Interaction Coefficients: The lower triangular BIC matrix is exported.
OPM Flow: The generated files are compatible with OPM Flow’s compositional mode.

Python Usage

from jpype import JClass

EclipseFluidReadWrite = JClass('neqsim.thermo.util.readwrite.EclipseFluidReadWrite')

# Export to E300 file
EclipseFluidReadWrite.write(fluid, "tuned_fluid.e300", 100.0)

# Read back
imported_fluid = EclipseFluidReadWrite.read("tuned_fluid.e300")

Integration with Whitson PVT Workflows

The export functionality enables seamless integration with PVT software like whitsonPVT:

EOS Tuning - Tune EOS parameters using experimental PVT data in NeqSim
C7+ Characterization - Use Whitson’s Gamma model for plus-fraction splitting
Export - Generate simulator-ready PVT files for reservoir engineering

// After EOS tuning and characterization
SystemInterface tunedFluid = /* ... tuned fluid model ... */;

// Export for reservoir simulation workflow
EclipseEOSExporter.toFile(tunedFluid, Path.of("TUNED_PVT.INC"));

API Reference

EclipseFluidReadWrite (Compositional EOS)

Method	Description
`read(String)`	Read E300 file into NeqSim fluid
`write(SystemInterface, String)`	Write fluid to E300 file
`write(SystemInterface, String, double)`	Write with reservoir temp (°C)
`toE300String(SystemInterface)`	Export to E300 format string
`toE300String(SystemInterface, double)`	Export with reservoir temp

EclipseEOSExporter (Black-Oil PVT)

Method	Description
`toString(SystemInterface)`	Export fluid to Eclipse format string
`toString(SystemInterface, ExportConfig)`	Export with configuration
`toString(BlackOilPVTTable, rhoO, rhoG, rhoW)`	Export PVT table
`toFile(SystemInterface, Path)`	Write to file
`toFile(SystemInterface, Path, ExportConfig)`	Write with configuration

CMGEOSExporter

Method	Description
`toString(SystemInterface)`	Export fluid to CMG format string
`toString(SystemInterface, ExportConfig)`	Export with configuration
`toString(BlackOilPVTTable, rhoO, rhoG, rhoW)`	Export PVT table
`toFile(SystemInterface, Path)`	Write to file
`toFile(SystemInterface, Path, ExportConfig)`	Write with configuration

Black Oil PVT and Reservoir Simulator Export

Comprehensive Java library for thermodynamic, physical property, and process simulation. NeqSim provides tools for PVT analysis, phase equilibria, transport properties, and full process simulation.

Black Oil PVT and Reservoir Simulator Export

Overview

Black Oil Conversion

Black Oil Properties

Eclipse Export

Basic Usage

Configuration Options

Export from Pre-computed PVT Table

Eclipse Output Format

DENSITY

PVTO (Live Oil)

PVTG (Wet Gas)

PVTW (Water)

Unit Systems

CMG Export

Basic Usage

Configuration Options

CMG Simulators

IMEX Output Format

Unit Systems

Complete Workflow Example

E300 Compositional EOS Export

E300 Format Background

Basic Usage

E300 File Keywords

Round-Trip: Export and Import

Optional E300 Keywords

LBCCOEF Support

PEDERSEN Support

BICS and SSHIFTS Support

Compatibility Notes

Python Usage

Integration with Whitson PVT Workflows

API Reference

EclipseFluidReadWrite (Compositional EOS)

EclipseEOSExporter (Black-Oil PVT)

CMGEOSExporter

See Also