CPA water, ice and hydrate boundaries

For a request such as water dew point with CPA or vannduggpunkt med CPA, calculate and report all three boundaries by default, unless the user explicitly requests only one. Explain the phase reference and convergence status of each.

Choose the interface

For a new fluid defined by JSON, prefer the connected run_flow_assurance capability with analysis: "waterPhaseBoundaries". Read its current schema and use validateInput before invocation. Supply explicit pressure_bara, temperature_C and a wet-basis components map. This analysis selects Statoil CPA and mixing rule 10 by default; the tested example also states model: "CPA" explicitly. Use only schema-defined fields for characterized oil fractions. See the executed JSON example.

For an existing configured, tuned or characterized Java fluid, retain that object's full model basis and use the combined facade operation below. Do not reconstruct it from a simpler JSON component map that omits its characterization or tuned parameters.

Configure the actual fluid

1. Use SystemSrkCPAstatoil and numeric setMixingRule(10). For a new fluid, add every component before selecting the mixing rule. Use kelvin and absolute pressure in bara.
2. Retain the complete component inventory, oil characterization, tuned parameters and phase options of an existing configured CPA fluid. Do not rebuild characterized oil from component names, strip oil or inhibitors, or force its overall composition into a single gas phase.
3. State the moisture basis. For wet-gas ppmv, use y_water = ppmv * 1e-6 and multiply normalized dry-gas fractions by 1 - y_water. For an oil/gas/water fluid, retain its actual water inventory and inhibitor concentrations rather than replacing these with gas ppmv.
4. Include MEG, methanol and other supplied inhibitors in the fluid. State their concentration and whether it is defined in the aqueous phase or in the whole fluid. Enable setMultiPhaseCheck(true) when the supplied system can contain oil, gas and aqueous liquid. Do not add free water to obtain a hydrate result.
5. Verify finite positive pressure and finite positive water content. The Java facade requires an already configured Statoil-CPA/rule-10 fluid; an unsupported model is an input problem, not permission for a silent conversion that loses characterization or tuning.

Calculate once and inspect every result

For an existing Java fluid, call new ThermodynamicOperations(fluid).cpaWaterPhaseBoundaryTemperatures(). It returns WaterPhaseBoundaryResult and calculates on independent copies, preserving the supplied fluid. Inspect getLiquidWater(), getIce() and getHydrate() separately. For each boundary, retain getStatus(), isConverged(), getTemperatureC(), getResidual(), getPhaseReference(), getWaterActivity() and getDiagnostic().

Report failed or inapplicable boundaries explicitly. Do not turn NaN, an unconverged iterate or a NOT_APPLICABLE result into a dew-point temperature. In a multiphase input, the fixed-feed-gas liquid-water dew point may be inapplicable; retain the reason while reporting the independently calculated ice and hydrate boundaries.

For the MCP route, inspect top-level status first. For error, report the error diagnostic and any retained partial data; do not assume a data object exists. For success or partial, inspect the data.liquidWater, data.ice and data.hydrate objects. Each contains status, converged, temperature_C, residual, waterActivity, phaseReference and diagnostic. Unavailable numerical values are JSON null. A partial comparison is not an all-boundaries-converged result; explain every failed or inapplicable boundary while retaining the usable results.

Explain the three temperatures

Treat these as separate onset calculations. The highest applicable equilibrium temperature is a candidate first boundary during cooling; after a phase forms, water and guest inventories change, so the other tabulated temperatures are not a sequential cooling trajectory. Equilibrium does not predict nucleation delay or hydrate growth rate.

Report composition, pressure, moisture/inhibitor bases, CPA model, rule 10, NeqSim version, phase references and per-boundary diagnostics. Compare with GERG-water only when requested and label its ISO ice/liquid reference separately; do not replace this CPA calculation with GERG-2008 or ISO 18453.

Use the tested setup and qualification guide. The gas-quality agent and thermo-fluid agent route these requests.