FluidClassifier provides screening classifications for reservoir-fluid studies. Choose one route deliberately: the methods do not reconcile composition, measured GOR, API gravity, and laboratory phase behavior into a single validated fluid description.

Choose the classification route

Route Input What it does
classify(fluid) NeqSim fluid Calculates C7+ mol% and applies the C7+ thresholds.
classifyByC7Plus(c7PlusMolPercent) C7+ in mol% Applies the composition thresholds directly.
classifyByGOR(gorScfStb) GOR in scf/STB Applies the GOR thresholds directly.
classifyWithPhaseEnvelope(fluid, reservoirTemperatureK) Fluid and reservoir temperature in K Starts from the C7+ result and heuristically refines it using a calculated critical temperature. If phase-envelope calculation fails, it returns the C7+ result.

classify(fluid) is therefore a C7+-screening route, not a phase-envelope calculation and not a measured-GOR correlation. Use the explicit GOR route when a representative producing GOR is the controlling input.

Implemented thresholds

The comparisons below describe the current public API exactly.

Result C7+ route (mol%) GOR route (scf/STB)
Dry gas < 0.7 > 100,000
Wet gas 0.7 to < 4.0 > 15,000 to <= 100,000
Gas condensate 4.0 to < 12.5 > 3,300 to <= 15,000
Volatile oil 12.5 to < 20.0 > 1,000 to <= 3,300
Black oil 20.0 to < 30.0 > 200 to <= 1,000
Heavy oil >= 30.0 <= 200

classifyByC7Plus returns UNKNOWN for a negative or NaN value. The current GOR route does not reject invalid values, so callers must require a finite, non-negative GOR before calling it.

Executable classification example

The program uses K, bara, mol%, and scf/STB explicitly. Run it with assertions enabled (java -ea ...); the documentation test compiles it for Java 8 and invokes it with assertions enabled.

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import neqsim.thermo.system.SystemInterface;
import neqsim.thermo.system.SystemSrkEos;
import neqsim.thermo.util.FluidClassifier;
import neqsim.thermo.util.ReservoirFluidType;

public final class FluidClassificationExample {
  private static final Logger logger =
      LogManager.getLogger(FluidClassificationExample.class);

  private FluidClassificationExample() {}

  public static void main(String[] args) {
    double temperatureK = 373.15;
    double pressureBara = 100.0;
    SystemInterface fluid = new SystemSrkEos(temperatureK, pressureBara);
    fluid.addComponent("methane", 0.75);
    fluid.addComponent("ethane", 0.10);
    fluid.addComponent("propane", 0.05);
    fluid.addComponent("n-heptane", 0.10);
    fluid.createDatabase(true);
    fluid.setMixingRule("classic");
    fluid.init(0);

    double c7PlusMolPercent = FluidClassifier.calculateC7PlusContent(fluid);
    ReservoirFluidType compositionScreen = FluidClassifier.classify(fluid);

    double producingGorScfStb = 5000.0;
    if (!Double.isFinite(producingGorScfStb) || producingGorScfStb < 0.0) {
      throw new IllegalArgumentException("GOR must be finite and non-negative");
    }
    ReservoirFluidType gorScreen = FluidClassifier.classifyByGOR(producingGorScfStb);

    assert Math.abs(c7PlusMolPercent - 10.0) < 1.0e-8;
    assert compositionScreen == ReservoirFluidType.GAS_CONDENSATE;
    assert gorScreen == ReservoirFluidType.GAS_CONDENSATE;

    String report = FluidClassifier.generateClassificationReport(fluid);
    assert report.contains("C7+ Content: 10.00 mol%");
    assert report.contains("Fluid Type: Gas Condensate");

    logger.info(
        "C7+ screen: {} mol%, composition={}, GOR={} scf/STB, GOR screen={}",
        c7PlusMolPercent,
        compositionScreen,
        producingGorScfStb,
        gorScreen);
  }
}

Engineering boundaries

Result metadata and reports

ReservoirFluidType exposes getDisplayName(), getTypicalGORRange(), and getTypicalC7PlusRange(). generateClassificationReport(fluid) reports the calculated C7+ screen, the typical ranges stored on the enum, an API-gravity estimate when available, and modeling recommendations. Parse neither the human-readable report nor the range strings as a stable data interface; retain the enum and numeric inputs in engineering records.

References

See also