Flow-Assurance Study Report

neqsim flow-assurance-report produces a reviewable flow-assurance study package in one step: a Word report (and PDF where Microsoft Word or LibreOffice is available) with 16 chapters and appendices, ten A3 pipeline drawing sheets (SVG, PNG, PDF), one canonical study dataset and a machine-readable validation report. It is the flow-assurance sibling of process-study report and reuses its report, drawing and validation helpers.

The pipeline lives in devtools/ (flow_assurance_report, fa_study, fa_solver, fa_geometry, fa_report, fa_diagrams, fa_validate, fa_handoff). The skill neqsim-flow-assurance-study-report holds the method and the agent @flow-assurance-study-report drives it. The calculation patterns remain in the neqsim-flow-assurance skill. Every command and code block on this page is executed by test_flow_assurance_study_report_documentation.py.

1. What it does and does not do

Supported (screening level) Not supported (reported as open or unsupported, never as safe)
Steady pressure, temperature, holdup, velocity and regime label with PipeBeggsAndBrills (SRK) Startup, restart, ramp-up, depressurisation, sweep-out
Backward solve: host pressure and rates given, source pressures calculated Pigging and slug-receiving requirements
Hydrate equilibrium margin with SRK-CPA, inhibited and uninhibited, MEG mass balance Severe and terrain slugging (Beggs and Brill does not qualify)
Lumped cooldown time to the hydrate temperature (not time to plug) Wax, asphaltene, scale and CO2 corrosion without inputs (open threats)
Erosional-velocity ratio against a project criterion DNV-RP-O501 erosion assessment
Topology variants that isolate sources or segments Bypass, reroute or added segments; more than one junction

Unsupported events get a hand-off file (handoff/EVT-*.json) for an external, qualified simulator; the result comes back with --external-results. Method qualification is recorded in Chapter 6 and Appendix G; no method is promoted beyond its evidence. The software never assigns the REVIEWED readiness label.

2. Quick start

The next block writes the input templates. Nothing is calculated: every value that must come from a source reads unavailable - TO BE CONFIRMED, and the command refuses to run on an unfilled template (exit code 2).

neqsim flow-assurance-report --init study_inputs

After filling route.yaml, basis.yaml and cases.yaml (the synthetic example in devtools/fa_examples/offshore_tieback/ shows every field; devtools/fa_examples/single_flowline/ is a second synthetic example with one source, no junction or PLEM and a route along one axis), run the study. --strict returns exit code 1 when a validation check fails.

neqsim flow-assurance-report route.yaml --basis basis.yaml --cases cases.yaml --out report --strict
neqsim flow-assurance-report --demo --out demo
neqsim flow-assurance-report study.json --basis basis.yaml --out report

The --demo run solves a synthetic two-template tie-back (eight cases, about one minute) and is the reference for the output layout. Without the neqsim command use <python> -m neqsim_cli flow-assurance-report ....

The shared runtime adapter uses neqsim_dev_setup to load compiled workspace classes in a source checkout or the installed NeqSim JAR outside one. It reuses an already running JVM, including the one started by a SURF study. Java, JPype and an available NeqSim classpath are required; a separate jneqsim Python package is not required.

3. Inputs

File Content
route.yaml assets with plan coordinates and elevation, segments with measured length, inside diameter, roughness, ambient, burial and layers (steel, coating, insulation)
basis.yaml study and document data, fluids, solver settings, acceptance criteria with sources, mitigation options, inspected sources, assumptions, data gaps and an optional human review record
cases.yaml cases (design, scenario, mitigation), topology variants, events
standards_register.yaml applicable standards with status and what was verified (public metadata only)

Rates are mass rates unless a standard density or the actual pressure and temperature are given. Inhibitor is specified as a lean stream or as an aqueous mass fraction target; mole fractions are never accepted as weight percent. The U-value is referenced to the inner pipe area, as the hydraulic solver uses pi x ID x L.

The inhibitor arithmetic is a pure function and is verified by the documentation test:

import sys
sys.path.insert(0, "devtools")
import fa_units

lean = fa_units.lean_injection_rate(water_rate=100.0, target_wt=0.30, purity_wt=0.90)
assert abs(fa_units.aqueous_wt_after_injection(100.0, lean, 0.90) - 0.30) < 1e-12
assert abs(lean - 50.0) < 1e-9
# 5 mol MEG per 15 mol water is 53 wt % MEG, not 25 wt %
meg = 5.0 * fa_units.MW["MEG"]
water = 15.0 * fa_units.MW["water"]
assert abs(fa_units.aqueous_wt_fraction(water, meg) - 0.534) < 0.005

4. Outputs

Folder Content
report/ Word report, PDF, validation_report.json and .md, report_facts.json
drawings/ svg/ (ten A3 sheets; nine for a single-path route, which has no second-path profile, DWG-04), png/, drawing PDF, layout_spec.json
dataset/ flow_assurance_study.json (schema flow_assurance_study.v1)
handoff/ external-simulator event packages
figures/, cache/ report figures; per-case solver cache keyed on the inputs and the NeqSim version

Drawing sheets: network schematic, route plan, longitudinal profiles per path, riser and PLEM arrangement, pipe and thermal cross-sections, velocity and holdup, hydrate margin, operating-limit summary and an event sheet.

5. Validation and readiness

About 30 checks run on the inputs, geometry, topology, solver, balances, boundary pressure, analytic benchmarks, mesh sensitivity, threats, events, standards, drawings (layout, data agreement with the dataset) and the document (every data token resolves with its unit, mandatory sections, open items visible). A failed check makes the package a NOT_READY diagnostic. A package from synthetic or schematic inputs, or with open threats or data gaps, is at most SCREENING.

6. Limits to keep in mind