Well Mechanical Design

NeqSim provides a comprehensive well mechanical design system for subsea wells, covering casing/tubing design, well barrier verification, weight estimation, and drilling & completion cost estimation.

Overview

The well design system follows the same three-layer architecture used throughout NeqSim’s mechanical design framework:

SubseaWell (equipment)
└── WellMechanicalDesign (design orchestration)
    ├── WellDesignCalculator (casing/tubing engineering)
    ├── WellMechanicalDesignDataSource (CSV standards loader)
    ├── WellBarrierSchematic (NORSOK D-010 two-barrier verification)
    │   ├── BarrierEnvelope (primary / secondary)
    │   │   └── BarrierElement (individual barrier components)
    │   └── Validation logic (element counts, DHSV/ISV, annulus monitoring)
    └── WellCostEstimator (drilling & completion costs)

Design factors, barrier requirements, and MAASP parameters are loaded from CSV standards databases at runtime — no magic numbers in code.

Applicable Standards

Standard Scope CSV Data File
NORSOK D-010 Rev 5 Well integrity, two-barrier principle, design factors norsok_standards.csv
API 5CT / ISO 11960 Casing and tubing grades and properties CasingProperties.csv
API Bull 5C3 / TR 5C3 Burst, collapse, and tension formulas api_standards.csv
API RP 90 Annular casing pressure management, MAASP api_standards.csv
ISO 16530-1 Well integrity lifecycle governance dnv_iso_en_standards.csv

Minimum Design Factors (NORSOK D-010)

Load Case Minimum DF
Burst 1.10
Collapse 1.00
Tension 1.60
Triaxial (VME) 1.25

Quick Start

// 1. Create fluid and stream
SystemInterface fluid = new SystemSrkEos(273.15 + 80.0, 200.0);
fluid.addComponent("methane", 0.80);
fluid.addComponent("ethane", 0.10);
fluid.addComponent("propane", 0.05);
fluid.setMixingRule("classic");

Stream stream = new Stream("reservoir", fluid);
stream.setFlowRate(50000.0, "kg/hr");
stream.setTemperature(80.0, "C");
stream.setPressure(200.0, "bara");

// 2. Create well with engineering properties
SubseaWell well = new SubseaWell("Producer-1", stream);
well.setWellType(SubseaWell.WellType.OIL_PRODUCER);
well.setCompletionType(SubseaWell.CompletionType.CASED_PERFORATED);
well.setRigType(SubseaWell.RigType.SEMI_SUBMERSIBLE);

// Geometry
well.setMeasuredDepth(3800.0);
well.setTrueVerticalDepth(3200.0);
well.setWaterDepth(350.0);

// Design conditions
well.setMaxWellheadPressure(345.0);
well.setReservoirPressure(400.0);
well.setReservoirTemperature(100.0);

// Casing program
well.setConductorOD(30.0);      well.setConductorDepth(100.0);
well.setSurfaceCasingOD(20.0);  well.setSurfaceCasingDepth(800.0);
well.setIntermediateCasingOD(13.375); well.setIntermediateCasingDepth(2500.0);
well.setProductionCasingOD(9.625);    well.setProductionCasingDepth(3800.0);

// Tubing
well.setTubingOD(5.5);
well.setTubingWeight(23.0);
well.setTubingGrade("L80");

// Drilling schedule
well.setDrillingDays(45.0);
well.setCompletionDays(25.0);
well.setRigDayRate(540000.0);

// Well barriers (NORSOK D-010)
well.setHasDHSV(true);
well.setPrimaryBarrierElements(3);
well.setSecondaryBarrierElements(3);

// 3. Run mechanical design
well.initMechanicalDesign();
WellMechanicalDesign design = (WellMechanicalDesign) well.getMechanicalDesign();
design.calcDesign();

// 4. Run cost estimation
design.calculateCostEstimate();

// 5. Get results
System.out.println("Wall thickness: " + design.getProductionCasingWallThickness() + " mm");
System.out.println("Burst DF: " + design.getProductionCasingBurstDF());
System.out.println("Barriers: " + (design.isBarrierVerificationPassed() ? "PASS" : "FAIL"));
System.out.println("Total cost: $" + design.getTotalCostUSD() / 1e6 + "M");
System.out.println(design.toJson());

Well Types and Enumerations

Well Type

SubseaWell.WellType.OIL_PRODUCER     // Oil production well
SubseaWell.WellType.GAS_PRODUCER     // Gas production well
SubseaWell.WellType.WATER_INJECTOR   // Water injection well
SubseaWell.WellType.GAS_INJECTOR     // Gas injection well
SubseaWell.WellType.OBSERVATION      // Observation / monitoring well

Completion Type

SubseaWell.CompletionType.CASED_PERFORATED  // Standard cased & perforated
SubseaWell.CompletionType.OPEN_HOLE         // Open hole (cost factor 0.70)
SubseaWell.CompletionType.GRAVEL_PACK       // Gravel pack (cost factor 1.30)
SubseaWell.CompletionType.ICD               // Inflow control device (1.25)
SubseaWell.CompletionType.AICD              // Autonomous ICD (1.45)
SubseaWell.CompletionType.MULTI_ZONE        // Multi-zone (1.80)

Rig Type

SubseaWell.RigType.SEMI_SUBMERSIBLE  // Semi-submersible (factor 1.0)
SubseaWell.RigType.DRILLSHIP         // Drillship (factor 1.20)
SubseaWell.RigType.JACK_UP           // Jack-up (factor 0.70)
SubseaWell.RigType.PLATFORM_RIG      // Platform rig (factor 0.60)

Casing Design

The WellDesignCalculator performs casing design for each string:

Load Cases

Burst (internal pressure exceeds external):

Collapse (external pressure exceeds internal):

Tension (axial load from casing weight):

Supported Casing Grades (API 5CT)

Grade SMYS (MPa) SMTS (MPa) Typical Use
H40 276 414 Conductor
J55 / K55 379 517-655 Surface casing
N80 / L80 552 655-689 Intermediate (L80 for sour service)
C90 / C95 621-655 689-724 Sour service
P110 758 862 Production casing
Q125 862 931 Ultra-high-strength
13Cr-L80 552 655 CO2 service (CRA)
25Cr 758 862 Severe corrosion (super duplex)

Example: Direct Calculator Usage

WellDesignCalculator calc = new WellDesignCalculator();
calc.setMeasuredDepth(3800.0);
calc.setWaterDepth(350.0);
calc.setMaxWellheadPressure(345.0);
calc.setReservoirPressure(400.0);

calc.setConductorCasing(30.0, 100.0);
calc.setSurfaceCasing(20.0, 800.0);
calc.setIntermediateCasing(13.375, 2500.0);
calc.setProductionCasing(9.625, 3800.0);
calc.setTubing(5.5, 23.0, "L80");

calc.calculateCasingDesign();
calc.calculateTubingDesign();
calc.calculateWeights();
calc.calculateCementVolumes();

Map<String, Object> results = calc.toMap();

Well Barrier Verification

NeqSim implements well barrier verification per NORSOK D-010 using a structured three-class model: BarrierElement → BarrierEnvelope → WellBarrierSchematic.

Barrier Elements (NORSOK D-010 Section 4)

A BarrierElement is an independent physical component that prevents uncontrolled flow. Each element has a type, functional status, and verification status.

BarrierElement dhsv = new BarrierElement(BarrierElement.ElementType.DHSV, "DHSV");
dhsv.setStatus(BarrierElement.Status.INTACT);
dhsv.setVerified(true);
dhsv.setInstallationDepth(500.0);

System.out.println(dhsv.isFunctional());  // true (INTACT or DEGRADED)

Supported element types (18 types per NORSOK D-010 Figure 3, Tables 20/36/37):

Type Description Typical Envelope
CASING Production casing Secondary
TUBING Tubing string Primary
PACKER Production packer Primary
DHSV Downhole safety valve (SSSV) Primary (producer)
ISV Injection safety valve Primary (injector)
WELLHEAD Wellhead and tubing hanger Both
XMAS_TREE Christmas tree Primary
CEMENT Cement (primary or secondary) Secondary
CASING_CEMENT Cement behind production casing Secondary
FORMATION Competent caprock Secondary
PLUG Bridge/cement plug Either
WING_VALVE Wing valve (WV/PWV) Primary
SWAB_VALVE Swab valve Primary
ASV Annular safety valve Secondary
KILL_VALVE Kill valve Secondary
GAUGE Downhole gauge —
ANNULUS_ACCESS_VALVE Annulus access valve Secondary
CHEMICAL_INJECTION_VALVE Chemical injection valve —

Barrier Envelopes (NORSOK D-010 Section 5)

A BarrierEnvelope groups elements into a complete pressure-containing boundary:

BarrierEnvelope primary = new BarrierEnvelope("Primary");
primary.addElement(new BarrierElement(BarrierElement.ElementType.TUBING, "Tubing"));
primary.addElement(new BarrierElement(BarrierElement.ElementType.DHSV, "DHSV"));
primary.addElement(new BarrierElement(BarrierElement.ElementType.XMAS_TREE, "Xmas Tree"));

boolean intact = primary.isIntact();              // true if all elements functional
boolean meets = primary.meetsMinimum(2);          // true if >= 2 functional elements
int functional = primary.getFunctionalElementCount();
boolean hasDhsv = primary.hasElementType(BarrierElement.ElementType.DHSV);

Barrier Schematic (Two-Barrier Principle)

The WellBarrierSchematic validates the complete barrier arrangement:

WellBarrierSchematic schematic = new WellBarrierSchematic();
schematic.setWellType("OIL_PRODUCER");

schematic.setPrimaryEnvelope(primary);
schematic.setSecondaryEnvelope(secondary);

schematic.validate();

if (schematic.isPassed()) {
    System.out.println("Two-barrier principle satisfied");
} else {
    for (String issue : schematic.getIssues()) {
        System.out.println(issue);
    }
}

Automatic validation checks:

Check Requirement Standard
Primary element count ≥ 2 functional elements NORSOK D-010 Sec 5
Secondary element count ≥ 2 functional elements NORSOK D-010 Sec 5
DHSV present (producers) Required in primary envelope NORSOK D-010 Table 20
ISV present (injectors) Required in primary envelope NORSOK D-010 Table 36
Annulus monitoring Required API RP 90
Envelope integrity All elements must be functional NORSOK D-010

Automatic Barrier Construction

When WellMechanicalDesign.calcDesign() runs, it automatically builds barrier envelopes from the SubseaWell configuration:

// Runs automatically during calcDesign()
design.calcDesign();

WellBarrierSchematic schematic = design.getBarrierSchematic();
Map<String, Object> barrierMap = schematic.toMap();
// Contains element-level detail: type, status, verified, installation depth

Legacy Barrier Verification

For backward compatibility, the count-based barrier verification still works when no schematic is configured:

well.setPrimaryBarrierElements(3);
well.setSecondaryBarrierElements(3);
well.setHasDHSV(true);

design.calcDesign();
boolean passed = design.isBarrierVerificationPassed();

Standards-Based Design Data

Design factors and requirements are loaded from CSV databases at runtime via WellMechanicalDesignDataSource. This eliminates hardcoded magic numbers and allows company/project-specific overrides.

How It Works

// WellMechanicalDesign.readDesignSpecifications() does this automatically:
WellMechanicalDesignDataSource dataSource = new WellMechanicalDesignDataSource();

// 1. Load NORSOK D-010 design factors from CSV
dataSource.loadNorskD010DesignFactors(calculator, isInjectionWell);
// Sets: burstDF=1.10, collapseDF=1.00 (or 1.10 for injectors), tensionDF=1.60, vmeDF=1.25

// 2. Load barrier requirements from CSV
Map<String, Double> barriers = dataSource.loadBarrierRequirements();
// Returns: minPrimaryElements, minSecondaryElements, dhsvRequired, isvRequiredInjector, ...

// 3. Load API RP 90 MAASP parameters
Map<String, Double> maasp = dataSource.loadApiRp90Parameters();
// Returns: safetyFactor, collapseFactor, pressureTolerance, decayTestDuration, maxDecayRate

// 4. Load ISO 16530 lifecycle requirements
Map<String, Double> lifecycle = dataSource.loadIso16530Requirements();
// Returns: integrityTestInterval, barrierVerificationInterval, cementEvaluationRequired

CSV Standards Files

The well design data comes from these standards CSV files in src/main/resources/designdata/standards/:

File Standards Example Specifications
norsok_standards.csv NORSOK D-010 BurstDesignFactor, CollapseDesignFactor, MinPrimaryBarrierElements, DHSVRequired
api_standards.csv API RP 90, API TR 5C3 MAASPSafetyFactor, BarlowBurstFormula, MaxPressureDecayRate
dnv_iso_en_standards.csv ISO 16530-1 WellIntegrityTestInterval, BarrierVerificationInterval

Production vs. Injection Design Factors

The data source automatically selects the right design factors based on well type:

Factor Production Well Injection Well Source
Burst DF 1.10 1.10 NORSOK D-010 Table 18
Collapse DF 1.00 1.10 NORSOK D-010 Table 18
Tension DF 1.60 1.60 NORSOK D-010 Table 18
Triaxial (VME) DF 1.25 1.25 NORSOK D-010

Note: injection wells use a higher collapse design factor (1.10 vs 1.00) because reversed pressure loads during shut-in can create collapse scenarios.

Cost Estimation

WellCostEstimator

The cost estimator provides detailed well cost breakdowns with regional factors.

WellCostEstimator estimator = new WellCostEstimator(SubseaCostEstimator.Region.NORWAY);
estimator.calculateWellCost(
    "OIL_PRODUCER",       // well type
    "SEMI_SUBMERSIBLE",   // rig type
    "CASED_PERFORATED",   // completion type
    3800.0,               // measured depth (m)
    350.0,                // water depth (m)
    45.0,                 // drilling days
    25.0,                 // completion days
    0.0,                  // rig day rate override (0 = use default)
    true,                 // has DHSV
    4                     // number of casing strings
);

System.out.println("Total: $" + estimator.getTotalCost() / 1e6 + "M");
System.out.println(estimator.toJson());

Cost Breakdown Structure

Category Components
Drilling Rig time, casing material, cement, mud, bits & tools
Completion Tubing, packers, screens, safety valves, rig time
Wellhead Subsea wellhead and Xmas tree assembly
Evaluation Logging, surveys, well testing
Contingency Default 15% on subtotal

Regional Cost Factors

Regional factors affect all cost components (rig rates, materials, services):

Region Factor Typical Well Cost (Oil Producer)
Norway (NCS) 1.35 Highest
UK North Sea 1.20 High
West Africa 1.10 Above average
US Gulf of Mexico 1.00 Baseline
Brazil 0.90 Below average

Bill of Materials

List<Map<String, Object>> bom = design.generateBillOfMaterials();
for (Map<String, Object> item : bom) {
    System.out.printf("%s: %.0f %s%n",
        item.get("name"), item.get("quantity"), item.get("unit"));
}

BOM includes: conductor, surface, intermediate, and production casing (by depth), production tubing, wellhead assembly, DHSV, and cement.

JSON Export

toJson() produces a comprehensive report:

{
  "equipmentType": "SubseaWell",
  "designStandardCode": "NORSOK-D-010",
  "configuration": {
    "wellType": "OIL_PRODUCER",
    "completionType": "CASED_PERFORATED",
    "rigType": "SEMI_SUBMERSIBLE",
    "hasDHSV": true,
    "numberOfCasingStrings": 4
  },
  "geometry": {
    "measuredDepthM": 3800.0,
    "trueVerticalDepthM": 3200.0,
    "waterDepthM": 350.0
  },
  "casingProgram": {
    "conductorOD_in": 30.0,
    "surfaceCasingOD_in": 20.0,
    "intermediateCasingOD_in": 13.375,
    "productionCasingOD_in": 9.625
  },
  "designResults": {
    "productionCasingWallThicknessMm": 8.9,
    "productionCasingBurstDF": 1.52,
    "productionCasingCollapseDF": 2.31,
    "productionCasingTensionDF": 4.87
  },
  "weights": {
    "totalCasingWeightTonnes": 185.3,
    "totalTubingWeightTonnes": 42.5,
    "totalCementVolumeM3": 78.2
  },
  "barrierVerification": {
    "verificationPassed": true,
    "notes": ["PASS: Two-barrier principle satisfied per NORSOK D-010"]
  },
  "costEstimation": {
    "totalCostUSD": 45200000,
    "drillingCostUSD": 24300000,
    "completionCostUSD": 12100000,
    "wellheadCostUSD": 3375000
  },
  "schedule": {
    "drillingDays": 45,
    "completionDays": 25,
    "totalDays": 70
  }
}

Integration with Field Development

FieldDevelopmentCostEstimator uses WellCostEstimator internally when well parameters are configured:

FieldDevelopmentCostEstimator costEst = new FieldDevelopmentCostEstimator(facility);
costEst.setSubseaParameters(15.0, 350.0);     // 15 km tieback, 350m water depth
costEst.setWellParameters(6, 3, 3800.0);      // 6 producers, 3 injectors, avg 3800m MD

FieldDevelopmentCostReport report = costEst.estimateDevelopmentCosts();

Class Reference

Class Package Purpose
SubseaWell neqsim.process.equipment.subsea Equipment class with well engineering properties
WellMechanicalDesign neqsim.process.mechanicaldesign.subsea Design orchestration, barrier verification, JSON reporting
WellDesignCalculator neqsim.process.mechanicaldesign.subsea Casing/tubing burst, collapse, tension calculations
WellMechanicalDesignDataSource neqsim.process.mechanicaldesign.subsea Loads design factors from CSV standards databases
BarrierElement neqsim.process.mechanicaldesign.subsea Single barrier element (type, status, depth)
BarrierEnvelope neqsim.process.mechanicaldesign.subsea Ordered collection of elements forming one envelope
WellBarrierSchematic neqsim.process.mechanicaldesign.subsea Primary + secondary envelopes with NORSOK D-010 validation
WellCostEstimator neqsim.process.mechanicaldesign.subsea Drilling & completion cost estimation
AnnularLeakagePath neqsim.process.equipment.reservoir Annular leakage + MAASP calculation per API RP 90

Data Files

File Path Content
WellCostData.csv src/main/resources/designdata/ Well cost parameters by type and rig
CasingProperties.csv src/main/resources/designdata/ API 5CT casing grade properties (SMYS, SMTS)
norsok_standards.csv src/main/resources/designdata/standards/ NORSOK D-010 design factors, barrier requirements
api_standards.csv src/main/resources/designdata/standards/ API RP 90 MAASP parameters, API TR 5C3 burst formula
dnv_iso_en_standards.csv src/main/resources/designdata/standards/ ISO 16530-1 lifecycle requirements