Pipeline Networks

Documentation for pipeline network modeling in NeqSim.

Table of Contents

• Overview
• PipeFlowNetwork
• WellFlowlineNetwork
• Network Architecture
• Usage Examples
• Advanced Features
• Related Documentation

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Overview

Location: neqsim.process.equipment.network

The network package provides classes for modeling interconnected pipeline systems where multiple pipelines converge at manifolds. This is essential for:

• Gas gathering systems
• Oil production networks
• Subsea tie-backs
• Distribution networks
• Well flowline networks

Class	Description
PipeFlowNetwork	Compositional network with TDMA solver
WellFlowlineNetwork	Network using Beggs-Brill correlations

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PipeFlowNetwork

The PipeFlowNetwork class models pipeline networks where multiple pipelines converge to manifolds, using compositional OnePhasePipeLine with TDMA (Tri-Diagonal Matrix Algorithm) solvers.

Class Hierarchy

ProcessEquipmentBaseClass
└── PipeFlowNetwork
    ├── contains: ManifoldNode[]
    └── contains: PipelineSegment[]

Key Features

• Compositional Tracking: Full compositional mass balance through the network
• Steady-State & Transient: Support for both solution modes
• Energy Balance: Heat transfer calculations included
• Graph-Based Architecture: Nodes (manifolds) connected by edges (pipelines)

Architecture

The network is modeled as a directed graph:

        [Feed 1]             [Feed 2]
           │                    │
           ▼                    ▼
      ┌─────────┐         ┌─────────┐
      │ Pipe 1  │         │ Pipe 2  │
      └────┬────┘         └────┬────┘
           │                   │
           ▼                   ▼
        ┌─────────────────────────┐
        │    Manifold A (Mixer)   │
        └───────────┬─────────────┘
                    │
                    ▼
             ┌─────────────┐
             │ Export Pipe │
             └──────┬──────┘
                    │
                    ▼
        ┌─────────────────────────┐
        │   End Manifold (Mixer)  │
        └───────────┬─────────────┘
                    │
                    ▼
              [Outlet Stream]

Inner Classes

PipelineSegment

Represents a pipeline in the network:

public static class PipelineSegment {
    String name;
    OnePhasePipeLine pipeline;
    String fromManifold;  // null for inlet pipes
    String toManifold;
    
    boolean isInletPipeline();  // true if fromManifold is null
}

ManifoldNode

Represents a junction/manifold in the network:

public static class ManifoldNode {
    String name;
    Mixer mixer;
    List<PipelineSegment> inboundPipelines;
    PipelineSegment outboundPipeline;
    
    boolean isTerminal();  // true if no outbound pipeline
}

Constructors

import neqsim.process.equipment.network.PipeFlowNetwork;

// Basic constructor
PipeFlowNetwork network = new PipeFlowNetwork("gathering network");

Key Methods

Method	Description
createManifold(String name)	Create a new manifold node
addInletPipeline(name, feed, toManifold, length, diameter, nodes)	Add inlet pipeline
connectManifolds(from, to, name, length, diameter, nodes)	Connect two manifolds
run()	Execute network simulation
getOutletStream()	Get the network outlet stream
getPipeline(String name)	Get a specific pipeline by name
getManifold(String name)	Get a manifold node by name

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Usage Examples

Gas Gathering Network

import neqsim.process.equipment.network.PipeFlowNetwork;
import neqsim.process.equipment.stream.Stream;
import neqsim.thermo.system.SystemSrkEos;

// Create feed streams from wells
SystemInterface gas1 = new SystemSrkEos(320.0, 150.0);
gas1.addComponent("methane", 0.92);
gas1.addComponent("ethane", 0.05);
gas1.addComponent("propane", 0.03);
gas1.setMixingRule("classic");

Stream feed1 = new Stream("well-1", gas1);
feed1.setFlowRate(5.0, "MSm3/day");
feed1.run();

SystemInterface gas2 = new SystemSrkEos(315.0, 145.0);
gas2.addComponent("methane", 0.90);
gas2.addComponent("ethane", 0.06);
gas2.addComponent("propane", 0.04);
gas2.setMixingRule("classic");

Stream feed2 = new Stream("well-2", gas2);
feed2.setFlowRate(3.0, "MSm3/day");
feed2.run();

// Create network
PipeFlowNetwork network = new PipeFlowNetwork("gathering system");

// Create manifolds
String manifoldA = network.createManifold("manifold A");
String endManifold = network.createManifold("end manifold");

// Add inlet pipelines to manifold A
// Parameters: name, feedStream, toManifold, length(m), diameter(m), nodes
network.addInletPipeline("pipe1", feed1, manifoldA, 5000.0, 0.3, 50);
network.addInletPipeline("pipe2", feed2, manifoldA, 4500.0, 0.25, 45);

// Connect manifold A to end manifold with export pipeline
network.connectManifolds(manifoldA, endManifold, "export", 15000.0, 0.5, 100);

// Run steady-state simulation
network.run();

// Access results
StreamInterface outlet = network.getOutletStream();
System.out.println("Outlet pressure: " + outlet.getPressure("bara") + " bara");
System.out.println("Outlet temperature: " + outlet.getTemperature("C") + " °C");
System.out.println("Total flow: " + outlet.getFlowRate("MSm3/day") + " MSm3/day");

Multi-Tier Network

// Create complex gathering network
PipeFlowNetwork network = new PipeFlowNetwork("field gathering");

// Create manifold hierarchy
String tier1ManifoldA = network.createManifold("tier1-A");
String tier1ManifoldB = network.createManifold("tier1-B");
String tier2Manifold = network.createManifold("tier2");
String centralManifold = network.createManifold("central");

// Tier 1: Wells to first-level manifolds
network.addInletPipeline("well1", well1Stream, tier1ManifoldA, 2000.0, 0.2, 30);
network.addInletPipeline("well2", well2Stream, tier1ManifoldA, 2500.0, 0.2, 30);
network.addInletPipeline("well3", well3Stream, tier1ManifoldB, 1800.0, 0.2, 30);
network.addInletPipeline("well4", well4Stream, tier1ManifoldB, 3000.0, 0.2, 30);

// Tier 2: First-level to second-level
network.connectManifolds(tier1ManifoldA, tier2Manifold, "line-A", 5000.0, 0.35, 50);
network.connectManifolds(tier1ManifoldB, tier2Manifold, "line-B", 4500.0, 0.35, 50);

// Tier 3: Second-level to central
network.connectManifolds(tier2Manifold, centralManifold, "export", 10000.0, 0.5, 100);

// Run
network.run();

Accessing Pipeline Results

// Run network
network.run();

// Access specific pipeline
PipeFlowNetwork.PipelineSegment segment = network.getPipelineSegment("pipe1");
OnePhasePipeLine pipeline = segment.getPipeline();

// Get pressure profile
double[] pressures = pipeline.getPressureProfile();
double[] positions = pipeline.getPositionProfile();

for (int i = 0; i < positions.length; i++) {
    System.out.printf("Position: %.1f m, Pressure: %.2f bara%n", 
                      positions[i], pressures[i]);
}

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WellFlowlineNetwork

A simplified network model using Beggs-Brill correlations instead of the full TDMA solver.

Key Differences from PipeFlowNetwork

Aspect	PipeFlowNetwork	WellFlowlineNetwork
Flow Model	TDMA solver	Beggs-Brill correlation
Compositional	Full	Simplified
Speed	Slower	Faster
Accuracy	Higher	Lower
Use Case	Detailed analysis	Quick screening

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Advanced Features

Transient Simulation

PipeFlowNetwork network = new PipeFlowNetwork("transient network");
// ... setup network ...

// Configure transient parameters
network.setTransientMode(true);
network.setTimeStep(1.0);  // seconds

// Run transient for 1 hour
for (double t = 0; t < 3600; t += 1.0) {
    // Update boundary conditions if needed
    feed1.setFlowRate(5.0 + 0.5 * Math.sin(t / 600), "MSm3/day");
    feed1.run();
    
    network.run();
    
    if (t % 60 == 0) {
        System.out.printf("t=%.0f s, P_outlet=%.2f bara%n", 
                          t, network.getOutletStream().getPressure("bara"));
    }
}

Heat Transfer

// Configure pipeline heat transfer
OnePhasePipeLine pipeline = network.getPipelineSegment("export").getPipeline();
pipeline.setOuterTemperature(278.15);  // Ambient temperature (K)
pipeline.setOverallHeatTransferCoefficient(5.0);  // W/m²/K

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Design Considerations

Network Topology

• Ensure no cycles in the network (currently supports tree structures)
• Each manifold should have at least one inbound pipeline
• Only the terminal manifold should have no outbound pipeline

Pressure Matching

• Feed stream pressures should be high enough to deliver to manifolds
• Back-pressure from downstream affects all upstream pipelines

Computational Performance

• Use fewer nodes for quick estimates
• Use more nodes (50-100 per km) for accurate pressure profiles
• Consider WellFlowlineNetwork for large screening studies

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Related Documentation

• Pipelines - Single pipeline modeling
• Manifolds - Manifold equipment
• Mixers - Stream mixing
• Subsea Systems - Subsea production