CO2 Injection Well Analysis Module

Five new classes provide an integrated analysis workflow for CO2 injection wells where impurity enrichment (hydrogen, nitrogen, methane) in the gas phase during two-phase conditions is a safety concern.

Class Overview

Class	Package	Purpose
`CO2InjectionWellAnalyzer`	`process.equipment.pipeline`	High-level orchestrator — runs all analyses and returns safety verdict
`ImpurityMonitor`	`process.measurementdevice`	Phase-partitioned composition tracking with alarm thresholds
`TransientWellbore`	`process.equipment.pipeline`	Shutdown cooling simulation (exponential decay to geothermal profile)
`CO2FlowCorrections`	`process.equipment.pipeline`	Static utility — CO2-specific holdup and friction correction factors
`PipeBeggsAndBrills`	`process.equipment.pipeline`	Enhanced with formation temperature gradient support (NIP-1)

Architecture

CO2InjectionWellAnalyzer (orchestrator)
├── PipeBeggsAndBrills (steady-state wellbore flow)
│   ├── Formation Temperature Gradient (NIP-1)
│   └── CO2FlowCorrections (NIP-4)
├── ImpurityMonitor (NIP-2)
│   └── Phase-partitioned K-value tracking
├── TransientWellbore (NIP-3)
│   └── Shutdown cooling + phase evolution
└── ThrottlingValve (choke JT analysis)

CO2InjectionWellAnalyzer

Package: neqsim.process.equipment.pipeline

Combines steady-state wellbore simulation, phase boundary scanning, impurity enrichment mapping, shutdown assessment, and choke JT analysis into a single analysis tool.

API

CO2InjectionWellAnalyzer analyzer = new CO2InjectionWellAnalyzer("InjectionWell-1");

// Configure
analyzer.setFluid(co2Fluid);
analyzer.setWellGeometry(1300.0, 0.1571, 4.5e-5);        // depth, ID, roughness [m]
analyzer.setOperatingConditions(90.0, 25.0, 150000.0);    // WHP [bara], WHT [C], flow [kg/hr]
analyzer.setFormationTemperature(4.0, 43.0);               // top C, bottom C
analyzer.addTrackedComponent("hydrogen", 0.04);            // name, alarm mol frac

// Run
analyzer.runFullAnalysis();

// Results
boolean safe = analyzer.isSafeToOperate();
Map<String, Object> results = analyzer.getResults();
Map<String, Object> designCase = (Map<String, Object>) results.get("design_case");
Map<String, Object> alarms = (Map<String, Object>) designCase.get("alarm_results");

isSafeToOperate() is a design-outlet screening result: it requires one phase, no exceeded registered gas-phase impurity alarm, and an evaluable reading for every registered component. It returns false before analysis, after a configuration change until analysis is rerun, or when a registered component is missing or its reading is unavailable. A positive result does not establish well integrity, including casing and cement condition, or shutdown safety. The separate cold-pressure safe_operating_envelope scan does not determine this design-outlet verdict. Thresholds are mole fractions, with 0 disabling an alarm as in ImpurityMonitor; an absent gas phase has no applicable gas alarm.

Results Map Keys

Key	Type	Description
`design_case`	Map	Outlet BHP, BHT, phase count, and registered design alarm status
`phase_boundary_scan`	Map	Two-phase counts and pressure/temperature bounds in the scan
`enrichment_map`	Map	Impurity scan by temperature
`shutdown_assessment`	Map	Approximate shutdown results at sampled pressures
`safe_operating_envelope`	Map	Separate cold-pressure phase and impurity screen

The returned map currently groups the results under design_case, phase_boundary_scan, enrichment_map, shutdown_assessment, and safe_operating_envelope. The design_case contains BHP_bara, BHT_C, n_phases, flow_regime, any_alarm_exceeded, alarms_evaluable, and alarm_results. For each registered component, alarm_results contains threshold_mol_frac, gas_mol_frac (null if unavailable or inapplicable), alarm_exceeded, and status (within_limit, exceeded, no_gas_phase, disabled, component_missing, or unavailable). A missing component or unavailable reading makes alarms_evaluable false and the screening verdict false. Call analyzer.isSafeToOperate() for the verdict; the map does not currently have a top-level safe_to_operate key.

ImpurityMonitor

Package: neqsim.process.measurementdevice

A measurement device that reads from a connected stream and tracks the phase-partitioned composition of selected impurity components. Reports enrichment factors (K-values) and triggers alarms when gas-phase concentrations exceed configurable thresholds.

API

ImpurityMonitor monitor = new ImpurityMonitor("WH-H2-Monitor", stream);
monitor.addTrackedComponent("hydrogen", 0.04);   // alarm at 4 mol%
monitor.addTrackedComponent("nitrogen", 0.10);   // alarm at 10 mol%
monitor.setPrimaryComponent("hydrogen");          // for getMeasuredValue()

// After process.run():
double h2InGas   = monitor.getGasPhaseMoleFraction("hydrogen");    // y_H2
double h2InLiq   = monitor.getLiquidPhaseMoleFraction("hydrogen");  // x_H2
double h2Bulk    = monitor.getBulkMoleFraction("hydrogen");         // z_H2
double enrichment = monitor.getEnrichmentFactor("hydrogen");       // y/z
boolean alarm     = monitor.isAlarmExceeded("hydrogen");           // y > 0.04?
int nPhases       = monitor.getNumberOfPhases();
double gasFrac    = monitor.getGasPhaseFraction();                 // gas beta

Map<String, Map<String, Double>> report = monitor.getFullReport();

Supported Units for `getMeasuredValue(String unit)`

Unit	Description
`"mol%"`	Mole percent (default)
`"ppm"`	Parts per million
`"mole fraction"`	Raw mole fraction

TransientWellbore

Package: neqsim.process.equipment.pipeline

Simulates the thermal evolution of a wellbore after injection stops. The model divides the wellbore into vertical segments and applies exponential temperature decay toward the formation temperature at each depth. At each time step, a TP flash determines if two-phase conditions develop and tracks impurity enrichment.

API

TransientWellbore well = new TransientWellbore("InjWell", feedStream);
well.setWellDepth(1300.0);                              // meters
well.setTubingDiameter(0.1571);                         // meters
well.setFormationTemperature(277.15, 316.15);           // top K, bottom K
well.setShutdownCoolingRate(5.0);                       // time constant [hours]
well.setNumberOfSegments(20);
well.setRadialHeatTransferCoefficient(25.0);            // W/(m2 K)
well.setDepressurizationRate(5.0);                      // bar/hr (0 = constant P)

// Run
well.runShutdownSimulation(24.0, 1.0);  // 24 hours, 1-hour steps

// Results
List<TransientSnapshot> snapshots = well.getSnapshots();
List<double[]> tempProfiles = well.getTemperatureProfiles();
double[] times = well.getTimePoints();
double maxH2 = well.getMaxGasPhaseConcentration("hydrogen");

TransientSnapshot Fields

Field	Type	Description
`timeHours`	double	Simulation time
`depths[]`	double[]	Depth at each segment [m]
`temperatures[]`	double[]	Temperature at each segment [K]
`pressures[]`	double[]	Pressure at each segment [bara]
`numberOfPhases[]`	int[]	Phase count at each segment
`gasFraction[]`	double[]	Gas mole fraction at each segment
`gasCompositions`	Map	Component gas-phase compositions at each segment

CO2FlowCorrections

Package: neqsim.process.equipment.pipeline

Static utility class providing CO2-specific correction factors for the Beggs and Brill (1973) multiphase flow correlation. The standard correlation was developed for oil-gas-water systems and may not accurately represent CO2-dominated streams where the liquid phase is dense-phase CO2.

API

// Check applicability
boolean isCO2 = CO2FlowCorrections.isCO2DominatedFluid(system);   // >50 mol% CO2
double xCO2   = CO2FlowCorrections.getCO2MoleFraction(system);

// Correction factors
double holdupFactor  = CO2FlowCorrections.getLiquidHoldupCorrectionFactor(system);   // 0.70-0.85
double frictionFactor = CO2FlowCorrections.getFrictionCorrectionFactor(system);      // 0.85-0.95

// Phase state
boolean dense = CO2FlowCorrections.isDensePhase(system);           // T>Tc AND P>Pc
double Tr     = CO2FlowCorrections.getReducedTemperature(system);  // T/Tc
double Pr     = CO2FlowCorrections.getReducedPressure(system);     // P/Pc

// Surface tension
double sigma  = CO2FlowCorrections.estimateCO2SurfaceTension(system);  // N/m

Correction Factor Behaviour

Condition	Holdup Factor	Friction Factor
Near-critical ($T_r > 0.95$)	0.70	0.85
Intermediate ($0.85 < T_r < 0.95$)	0.70 - 0.85 (linear)	0.95
Subcritical ($T_r < 0.85$)	0.85	0.95

Constants: $T_c = 304.13$ K, $P_c = 73.77$ bara, CO2 threshold = 50 mol%.

Reference: Peletiri, S.P., Rahmanian, N. and Mujtaba, I.M. (2018). CO2 Pipeline Design: A Review. Energies, 11(9), 2184.

PipeBeggsAndBrills — Formation Temperature Gradient (NIP-1)

Package: neqsim.process.equipment.pipeline

The existing PipeBeggsAndBrills class was enhanced with a formation temperature gradient model. Previously, only a constant surface temperature could be specified. Now the heat transfer calculation uses a depth-dependent formation temperature profile for realistic geothermal gradient modelling.

New Methods

PipeBeggsAndBrills pipe = new PipeBeggsAndBrills(inletStream);

// Set formation temperature gradient
// For a well with 4 C at wellhead and 30 C/km geothermal gradient:
pipe.setFormationTemperatureGradient(4.0, -0.03, "C");
//                                  ^inlet ^gradient ^unit
// Sign convention: negative gradient = temperature INCREASES with depth
//                  (negative elevation change in injection wells)

double grad = pipe.getFormationTemperatureGradient();   // returns K/m

Impact on Results (Example)

Parameter	Without Gradient	With Gradient	Difference
BHT	4.1 °C	42.8 °C	+38.7 °C
BHP	200.5 bara	183.7 bara	-16.8 bar

The formation temperature gradient significantly affects the fluid density along the wellbore, which changes the hydrostatic pressure contribution. Warmer fluid is less dense, resulting in lower bottom-hole pressure.

Integration Workflow

These classes are designed to work together for CO2 injection well safety analysis. The typical workflow is:

Create fluid — Define CO2-rich injection composition
Steady-state — Run PipeBeggsAndBrills with formation gradient
Phase scan — Map the two-phase region with TP flash
Enrichment — Use ImpurityMonitor to track H2/N2 in gas phase
Shutdown — Run TransientWellbore for thermal transient
Safety — Use CO2InjectionWellAnalyzer for integrated assessment

Python / Jupyter Example

from neqsim import jneqsim
import jpype

# Load classes
SystemSrkEos = jneqsim.thermo.system.SystemSrkEos
Stream = jneqsim.process.equipment.stream.Stream
CO2InjectionWellAnalyzer = jpype.JClass(
    "neqsim.process.equipment.pipeline.CO2InjectionWellAnalyzer")

# Create fluid
fluid = SystemSrkEos(273.15 + 25.0, 90.0)
fluid.addComponent("CO2", 0.96225)
fluid.addComponent("nitrogen", 0.01975)
fluid.addComponent("methane", 0.008)
fluid.addComponent("hydrogen", 0.0075)
fluid.addComponent("argon", 0.00175)
fluid.addComponent("CO", 0.00075)
fluid.setMixingRule("classic")

# Run integrated analysis
analyzer = CO2InjectionWellAnalyzer("InjectionWell-1")
analyzer.setFluid(fluid)
analyzer.setWellGeometry(1300.0, 0.1571, 4.5e-5)
analyzer.setOperatingConditions(90.0, 25.0, 150000.0)
analyzer.setFormationTemperature(4.0, 43.0)
analyzer.addTrackedComponent("hydrogen", 0.04)
analyzer.runFullAnalysis()

print("Safe:", analyzer.isSafeToOperate())
results = dict(analyzer.getResults())
print("Min safe WHP:", results.get("min_safe_WHP_bara"), "bara")

Beggs & Brill Pipe Flow — Base multiphase flow correlation
Pipeline Equipment — Pipeline and riser models
Well Mechanical Design — Casing/tubing design per NORSOK D-010
Process Design Guide — Complete process design workflow

CO2 Injection Well Analysis Module

Class Overview

Architecture

CO2InjectionWellAnalyzer

API

Results Map Keys

ImpurityMonitor

API

Supported Units for getMeasuredValue(String unit)

TransientWellbore

API

TransientSnapshot Fields

CO2FlowCorrections

API

Correction Factor Behaviour

PipeBeggsAndBrills — Formation Temperature Gradient (NIP-1)

New Methods

Impact on Results (Example)

Integration Workflow

Python / Jupyter Example

Related Documentation

Supported Units for `getMeasuredValue(String unit)`