Chemistry and Integrity Modelling

NeqSim ships an open, standards-traceable chemistry stack for chemical-integrity management of oil & gas, CCS and hydrogen systems. Every routine carries an explicit list of source standards (NORSOK, NACE, ISO, API, ASTM) so results are auditable.

All classes live under neqsim.process.chemistry. The same routines are exposed over the Model Context Protocol as runChemistry.

Capability matrix

Threat Class Model Standards
Mineral scale scale.ScalePredictionCalculator Oddo–Tomson SI NACE TM0374
Mineral scale (rigorous) scale.ElectrolyteScaleCalculator Davies activity-coeff SI for CaCO3, BaSO4, CaSO4, SrSO4 NACE TM0374, NORSOK M-001
Pipeline deposition scale.ScaleDepositionAccumulator Per-segment SI × velocity × time NACE SP0775
Closed-loop deposition scale.ClosedLoopDepositionSolver Iterates effective diameter against deposition NACE SP0775
CO2 corrosion corrosion.CorrosionCalculator NORSOK M-506 base NORSOK M-506
CO2 corrosion (mechanistic) corrosion.MechanisticCorrosionModel NORSOK + Nesic Sherwood mass-transfer + Langmuir inhibitor NORSOK M-506, NACE SP0775
Inhibitor selection corrosion.LangmuirInhibitorIsotherm Van’t Hoff temperature-dependent Langmuir NACE SP0775
H2S scavenging scavenger.PackedBedScavengerReactor 1D plug-flow with capacity tracking NACE TM0169
Acid gas chemistry acid.AcidGasCalculator Equilibrium-based H2S/CO2 partitioning NACE MR0175 / ISO 15156
Hydrate / wax / asphaltene hydrate.*, wax.*, asphaltene.* NeqSim thermo + flash API RP 87
Root cause rca.RootCauseAnalyser Bayesian update across threats —

Coupled workflows

The closed-loop deposition solver couples PipeBeggsAndBrills hydraulics with ScaleDepositionAccumulator so velocity-dependent deposition is consistent with the shrinking effective diameter:

ClosedLoopDepositionSolver solver =
    new ClosedLoopDepositionSolver(pipe, accumulator)
        .setToleranceM(1e-4)
        .setMaxIterations(10);
solver.solve();
double dEff = solver.getFinalEffectiveDiameterM();
List<Double> velocityHistory = solver.getVelocityHistoryMs();

The packed-bed scavenger predicts breakthrough time for an H2S removal vessel:

PackedBedScavengerReactor bed = new PackedBedScavengerReactor()
    .setGeometry(0.5, 2.0, 0.4)            // d_m, h_m, voidage
    .setMedia(5.0, 1100.0, 1.0)            // mol/kg loading, density, stoich
    .setRateConstant(8.0)
    .setFeed(2.0, 0.005)                   // c_inlet mol/m3, Q m3/s
    .setSimulationTime(60.0 * 24 * 3600.0, 0.05)
    .evaluate();
double tBreak = bed.getBreakthroughTimeS();
double removedKg = bed.getTotalH2sRemovedKg();

MCP integration

Every analysis is exposed over the NeqSim MCP server:

{
  "analysis": "mechanisticCorrosion",
  "temperature_C": 60,
  "pressure_bara": 80,
  "co2_mol": 0.05,
  "velocity_ms": 2.0,
  "diameter_m": 0.15,
  "dose_mgL": 50
}

Send this to the runChemistry tool. Supported analysis values: electrolyteScale, mechanisticCorrosion, langmuirInhibitor, packedBedScavenger.

See MCP chemistry tool reference for the full schema.

Reproducibility

Every routine is covered by JUnit tests in src/test/java/neqsim/process/chemistry/ and src/test/java/neqsim/mcp/runners/ChemistryRunnerTest.java. As of the latest release, 47 chemistry tests pass and serve as the regression baseline.

Deep-dive references

Worked example notebooks