Integrated Field Lifecycle Simulation

The neqsim.process.fielddevelopment.lifecycle package connects NeqSim’s detailed engineering models on one time axis. It is intended for comparing field-development concepts consistently, rather than estimating production and economics in disconnected spreadsheets.

flowchart TD
    A[Compositional PVT] --> B[Reservoir material balance]
    B --> C[Well deliverability]
    C --> D[SURF and flowline hydraulics]
    D --> E[Process plant]
    I[Existing host production profile] --> E
    E --> F[Oil and gas export]
    E --> G[Gas injection compression]
    G --> B
    F --> H[Norwegian cash flow]
    G --> H

What is solved at each time step

  1. Well deliverability is calculated from producer count, productivity index, reservoir pressure and minimum BHP.
  2. A NeqSim ProcessSystem or complete multi-area ProcessModel solves the new-field wells, shared SURF and host hydraulics at the live PVT state. A hydraulic pressure failure terminates the producing life as an explicit wells/SURF limit.
  3. FacilityCapacityAllocator applies oil, gas, water and total-liquid nameplate limits. Brownfield allocation delegates to the canonical tieback.capacity API and its CapacityAllocationPolicy.
  4. Existing-host and admitted new-field streams are mixed in the detailed shared process. Mechanical-design equipment constraints, facility power, and the annual primary bottleneck are evaluated after every solve.
  5. Produced gas is split between sale and injection, subject to compressor and injection-well capacity.
  6. SimpleReservoir.runTransient removes only admitted new-field oil/water, adds injected gas and performs a constant-volume flash. Held-back production therefore remains in the reservoir for later years.
  7. Export gas, stabilized oil and treated-water discharge are checked against their configured specifications.
  8. Power, emissions, utilization, host load, holdback, deferred production and annual product volumes are accumulated.
  9. CashFlowEngine("NO") calculates Norwegian after-tax NPV, IRR, payback and break-even oil/gas price.

Construction CAPEX can precede first oil without incorrectly charging production OPEX: the lifecycle integration uses CashFlowEngine.setFixedOpexStartYear to start fixed OPEX in the first production year.

The framework accepts any user-built ProcessSystem or multi-area ProcessModel. The supplied NorwegianOilFieldCase is therefore a reference assembly, not a fixed process template. Real well models, flowlines, risers, separators, compressor maps, water treatment, export equipment, mechanical constraints and host feeds can be connected through FieldLifecycleModel. Set a FieldProductionPotentialProvider on the model to replace the reference linear PI/water-cut potential with a detailed well/network solve, an imported reservoir-simulator schedule, or a calibrated surrogate. The resulting rate still passes through the live detailed SURF and facility process before reservoir material balance and economics are advanced.

Use an existing process plant or shared SURF model

For a brownfield study, map lifecycle roles to the actual streams in the user’s flowsheet. A single host process can be supplied directly:

FieldLifecycleModel hostModel = FieldLifecycleModel
    .existingFacility("Host A tie-in", reservoir, existingHostProcessSystem)
    .reservoirStreams(newFieldOil, newFieldWater, injectionWellFeed)
    .gasHandling(recoveredGas, exportInjectionSplitter, compressedInjectionGas)
    .exportStreams(stabilizedOil, salesGas)
    .hostFeeds(existingOilFeed, existingGasFeed, existingWaterFeed)
    .treatedWaterDischarge(treatedWater)
    .build();

Large real models can remain divided into areas. Supplying a ProcessModel causes the lifecycle engine to execute the complete model and aggregate power, automatic sizing, mechanical constraints and bottlenecks across every area:

ProcessModel infrastructure = new ProcessModel();
infrastructure.add("shared SURF", existingSurfProcess);
infrastructure.add("host topsides", existingFacilityProcess);

FieldLifecycleModel hostAndSurf = FieldLifecycleModel
    .existingSurfAndFacility("Shared SURF route", reservoir, infrastructure,
        "shared SURF", "host topsides")
    .reservoirStreams(newFieldOil, newFieldWater, injectionWellFeed)
    .gasHandling(recoveredGas, exportInjectionSplitter, compressedInjectionGas)
    .exportStreams(stabilizedOil, salesGas)
    .hostFeeds(existingOilFeed, existingGasFeed, existingWaterFeed)
    .treatedWaterDischarge(treatedWater)
    .build();

The process areas must already be connected by shared NeqSim streams. Place the new-field producer streams and the existing-asset feeds at the intended subsea tie-in nodes. Their actual position determines whether a shared flowline, pipeline, riser or topsides unit sees each load. Model-wide bottlenecks are reported as area::equipment, so a shared SURF restriction remains distinguishable from a facility restriction. The overload accepting separate existing SURF and facility ProcessSystem objects assembles the same two-area ProcessModel automatically.

Greenfield facility sizing

Attach a FacilityLifecycleStrategy.greenfield(...) to the lifecycle configuration. The simulator runs the detailed process at the design case, calls autoSizeEquipment(designMargin) on the supplied ProcessSystem or complete ProcessModel, registers mechanical-design-derived constraints, and records:

Component maxima do not need to occur simultaneously. Use explicit nameplateCapacity(...) for separate peak-oil, peak-gas and peak-water design cases. The rates passed to greenfield(...) represent the physically simultaneous process design case.

FacilityLifecycleStrategy greenfield = FacilityLifecycleStrategy
    .greenfield("New FPSO", new FacilityProductionRate(23000.0, 4.5e6, 1000.0))
    .nameplateCapacity(new FacilityCapacity(26450.0, 5.5e6, 32000.0, 52000.0, 0.0))
    .designMargin(1.15)
    .autoSizeDetailedProcess(true)
    .build();

FacilityDesignResult is retained in the lifecycle result so the economic comparison is traceable to the installed processing design.

Brownfield host and tieback studies

Brownfield concepts reuse HostFacility, ProductionProfileSeries, CapacityAllocationPolicy and HoldbackPolicy from neqsim.process.fielddevelopment.tieback.capacity. FieldLifecycleModel additionally exposes optional host oil, gas and water feed streams. These streams must be connected to the actual shared host flowsheet upstream of the constrained equipment.

This lifecycle layer reuses and complements the existing host tie-in capacity workflow; it adds the coupled reservoir, detailed process and economic time march rather than defining a second allocation model.

ProductionProfileSeries hostProfile = new ProductionProfileSeries("host")
    .addPeriod(2029, 3.2, 100636.0, 14000.0, 0.0)
    .addPeriod(2039, 1.4, 47173.0, 22000.0, 0.0);

FacilityLifecycleStrategy tieback = FacilityLifecycleStrategy
    .tieback("Existing host", hostFacility, hostProfile)
    .allocationPolicy(CapacityAllocationPolicy.BASE_FIRST)
    .holdbackPolicy(HoldbackPolicy.DEFER_TO_LATER_YEARS)
    .holdback(0.0, 0.10)
    .build();

Host points are linearly interpolated by calendar year. The configured allocation policy controls shared capacity:

Policy Lifecycle behavior
BASE_FIRST Preserve existing-host production and allocate remaining capacity to the new field
SATELLITE_FIRST Accelerate the new field before existing-host production
PRO_RATA Scale host and new-field requests by a common capacity factor
VALUE_WEIGHTED Use the canonical tie-in planner’s value-priority behavior

Planned host and satellite holdback fractions are applied before capacity allocation. DEFER_TO_LATER_YEARS is physically represented by not removing constrained new-field fluids from the reservoir; the retained reserves can be produced when the host declines and ullage opens. capacityFromYear(...) can represent a debottleneck project or a later host-capacity change, with the associated CAPEX entered in FieldLifecycleConfiguration.

For an existing real facility or SURF route, set autoSizeDetailedProcess(false) and supply the equipment’s actual design limits or capacity constraints. For a new facility, enable auto-sizing. Do not auto-size brownfield equipment unless the study is explicitly designing its replacement, rerating or a parallel train.

Bottlenecks and modification plans

Each annual result retains both admitted operating utilization and requested utilization before nameplate or detailed-equipment rate reduction. This avoids hiding a severe constraint behind a 100% capped operating point. FacilityModificationPlanner groups the evidence by first required year and bottleneck, relates it to deferred oil, and suggests a screening scope:

FieldLifecycleResult result = new FieldLifecycleEvaluator().evaluate(tiebackConcept);
FacilityModificationPlan plan = new FacilityModificationPlanner().analyse(result, 0.90);
String modificationTable = plan.toMarkdownTable();

Suggestions cover shared SURF rerating/looping/alternate routes, additional separation or water-treatment trains, compression, export and power modifications. The calculated capacity multiplier is a screening target. Implement and cost each candidate in a cloned detailed ProcessSystem or ProcessModel, rerun its complete lifecycle, and compare that executable modified concept with the unmodified and greenfield alternatives.

Product and discharge specifications

FieldProductSpecifications makes quality part of the executable concept rather than a post-processing note. The default evaluator uses live NeqSim streams and established functionality:

FieldProductSpecifications specifications = FieldProductSpecifications.builder()
    .gasComposition(2.5, 3.3)              // mol% CO2, ppm H2S
    .gasOxygen(0.0002)                     // mol% O2 (2 ppm)
    .gasDewPoints(70.0, -10.0, 0.0)        // bara, water-dew C, HC-dew C
    .gasEnergyContent(38.1, 43.7, 48.3, 52.8, 0.70) // GCV/Wobbe MJ/Sm3, relative density
    .oilExport(1.0, 0.5)                    // RVP bara, BS&W vol%
    .producedWater(30.0)                    // oil in water, mg/L
    .violationAction(FieldProductSpecifications.ViolationAction.REJECT_OPTION)
    .build();

The worst measurement and every violation are retained in each annual result. REPORT_ONLY keeps an option visible for diagnostic studies; REJECT_OPTION makes it ineligible for an area-development recommendation. A custom provider can read real online analysers, a produced-water compliance monitor, or another process-specific quality model.

Gas specifications are contract- and entry/exit-point-specific. The example is an illustrative teaching envelope, not a universal Gassled specification. The current Gassled terms include point-specific pressure, temperature, dew point, CO2, oxygen, sulphur, GCV, Wobbe-index and relative-density requirements. Some limits use mg/Nm3 and combine H2S with COS; convert those to the configured unit basis or supply a contract-specific FieldProductQualityProvider. Always verify values against the applicable Gassco transport agreement.

Gas transport booking and tariffs

Physical gas-processing/export capacity and commercially booked transport capacity are separate constraints. Gassco’s current framework distinguishes booked entry, exit, processing and quality-service capacity, including firm and interruptible bookings. For a concept study:

  1. set the facility gas envelope to the tightest physical or firm-booked capacity;
  2. use capacityFromYear(...) for a booking start, expiry or later capacity increase;
  3. model interruptible capacity as a separate sensitivity rather than guaranteed base capacity;
  4. enter the applicable throughput tariff with FieldLifecycleConfiguration.Builder.tariffs(...); and
  5. keep booking/capacity-fee commitments as explicit annual project OPEX assumptions.

This lets the annual allocator defer production when gas export is the binding constraint. It also prevents available pipeline diameter from being mistaken for an awarded transport right. The official Gassco capacity-booking overview describes primary, secondary and interruptible capacity processes.

Area development across several assets

AreaDevelopmentPortfolio evaluates a discovery against any number of independently assembled host routes and greenfield alternatives. Each host option owns its actual host production profile, nameplate envelope, detailed flowsheet, tie-in/SURF route, modification CAPEX, tariffs and product specifications.

AreaDevelopmentPortfolio portfolio = new AreaDevelopmentPortfolio("Northern area")
    .addOption(AreaDevelopmentOption.greenfield(
        "Standalone FPSO", "New area FPSO", greenfieldConcept))
    .addOption(AreaDevelopmentOption.tieback(
        "Tieback to Alpha", "Alpha platform", alphaHostConcept))
    .addOption(AreaDevelopmentOption.tieback(
        "Tieback to Bravo", "Bravo FPSO", bravoHostConcept));

AreaDevelopmentResult areaResult = new AreaDevelopmentEvaluator().evaluate(portfolio);
AreaDevelopmentResult.OptionResult recommended = areaResult.getRecommendedOption();
String areaComparison = areaResult.toMarkdownTable();

Options are ranked first by eligibility under the quality policy and then by after-tax NPV. The comparison preserves route and receiving-asset identity alongside oil recovery, deferment, operating and requested capacity utilization, break-even and off-spec years. Models cannot be shared between alternatives because reservoir and process state are mutable.

Run the representative Norwegian case

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import neqsim.process.fielddevelopment.lifecycle.FieldLifecycleConcept;
import neqsim.process.fielddevelopment.lifecycle.FieldLifecycleEvaluator;
import neqsim.process.fielddevelopment.lifecycle.FieldLifecycleResult;
import neqsim.process.fielddevelopment.lifecycle.NorwegianOilFieldCase;

Logger logger = LogManager.getLogger("field-lifecycle-example");

FieldLifecycleConcept gasInjection = NorwegianOilFieldCase.createGasInjectionCase();
FieldLifecycleResult result = new FieldLifecycleEvaluator().evaluate(gasInjection);

logger.info("After-tax NPV: {} MUSD", result.getNpvMusd());
logger.info("Break-even oil price: {} USD/bbl", result.getBreakevenOilPriceUsdPerBbl());
logger.info("Cumulative oil: {} MSm3", result.getCumulativeOilSm3() / 1.0e6);
logger.info("Gas injected: {} GSm3", result.getCumulativeGasInjectedSm3() / 1.0e9);

The synthetic reference case represents six subsea producers and three gas injectors tied to an FPSO in 300 m water depth. It uses PR-EOS with defined heavy fractions, a gas-cap/oil/water tank, aggregate multiphase tubing and flowline, HP/LP separation, oil export pumping, gas export and two-stage gas-injection compression. Well and SURF costs use WellCostEstimator and SURFCostEstimator; topsides and project costs are Class-4 parametric allowances.

Compare concepts

Every alternative must own an independent mutable reservoir/process model. The factory methods create independent instances:

import java.util.Arrays;
import java.util.List;
import neqsim.process.fielddevelopment.lifecycle.FieldLifecycleEvaluator;
import neqsim.process.fielddevelopment.lifecycle.FieldLifecycleResult;
import neqsim.process.fielddevelopment.lifecycle.NorwegianOilFieldCase;

FieldLifecycleEvaluator evaluator = new FieldLifecycleEvaluator();
List<FieldLifecycleResult> ranked = evaluator.evaluateAll(Arrays.asList(
    NorwegianOilFieldCase.createGasInjectionCase(),
    NorwegianOilFieldCase.createNaturalDepletionCase(),
    NorwegianOilFieldCase.createHostPriorityTiebackCase(),
    NorwegianOilFieldCase.createManagedTiebackCase()));

String comparison = evaluator.toMarkdownTable(ranked);

The reference portfolio gives the following reproducible screening result at the documented assumptions:

Concept NPV (MUSD) IRR (%) Oil break-even (USD/bbl) Oil (MSm3) Deferred oil (MSm3) Peak utilization (%)
New FPSO with gas injection -281 6.2 85.3 25.1 0.2 97.2
New FPSO, natural depletion -959 1.2 108.4 16.6 1.2 94.7
Tieback, host priority 247 11.9 58.9 16.3 13.6 100.0
Tieback, managed allocation 335 14.0 53.0 16.6 6.6 100.0
Tieback, remote host B 193 10.8 62.7 16.5 7.1 100.0

These are synthetic concept-screening results, not data for a named field. Their purpose is to show how facility design and host-allocation choices change production timing and project economics on a consistent basis.

Use NorwegianOilFieldCase.createDevelopmentPortfolio() for the same four concepts or createCase(name, recycleFraction, maximumInjectionRate) for recycling/compression sensitivities. For larger changes—well count, flowline size, separation pressure, host process or tie-in location—assemble a new FieldLifecycleModel with the relevant NeqSim equipment and retain a common economic basis.

Each annual result exposes potential and requested new-field oil rate, admitted host oil/gas/water, deliberate holdback, capacity-deferred oil, admitted utilization, requested utilization and both associated bottlenecks. The top-level result exposes cumulative deferred oil, peak operating utilization and peak requested utilization. These fields allow reviewers to distinguish subsurface decline, planned rate shaping, host ullage, shared SURF constraints, and physical equipment limits.

Use NorwegianOilFieldCase.createAreaDevelopmentPortfolio() for a standalone facility, two distinct producing hosts, and a managed-allocation variant assembled on the same synthetic basis.

Engineering methods and fidelity

Area Reference implementation Method and intended fidelity
PVT SystemPrEos Compositional cubic EOS with defined C7-C21+ fractions
Reservoir SimpleReservoir Constant-volume tank material balance with compositional injection; screening/concept
Wells FieldLifecycleConfiguration and InjectionWellModel Linear oil PI/drawdown; radial Darcy injectivity and fracture-pressure limit
Tubing/flowlines PipeBeggsAndBrills Steady-state multiphase Beggs-Brill hydraulics
Process plant ProcessSystem / ProcessModel equipment Rigorous flashes, three-phase separators, pumps, compressors and coolers in one or several process areas
Greenfield sizing autoSizeEquipment, mechanical design constraints Equipment sizing at a simultaneous design case plus component nameplate envelopes
Brownfield allocation tieback.capacity and HostFacility Calendar-year host profile, canonical allocation/holdback policies and shared ullage
Bottlenecking ProcessSystem / ProcessModel bottleneck APIs Annual nameplate, power, shared SURF and detailed equipment utilization after the combined process solve
Product quality NeqSim dew-point analysers, ISO 6976, ASTM D6377 RVP, Standard_BSW Annual gas/oil export and treated-water compliance
Area routing AreaDevelopmentPortfolio Independent multi-host and greenfield lifecycle alternatives ranked by eligibility and NPV
SURF/well CAPEX SURFCostEstimator, WellCostEstimator NCS benchmark correlations, Class-4 concept estimate
Economics CashFlowEngine("NO") Norwegian corporate/petroleum tax, depreciation, uplift, NPV/IRR and break-even

The reference reservoir has no spatial grid. Sweep efficiency, coning, compositional fronts, well interference and history matching require a reservoir simulator or calibrated surrogate. At FEED fidelity, replace the tank rate/pressure state with imported reservoir schedules while retaining the same surface process, constraint and economics interfaces.

Main API

Class Purpose
FieldLifecycleConfiguration Shared production, capacity, injection, emissions and economic assumptions
FacilityLifecycleStrategy Greenfield sizing or brownfield host/profile/allocation/holdback strategy
FacilityCapacity Oil, gas, water, liquid and power nameplate envelope, including scheduled upgrades
FacilityCapacityAllocator Lifecycle adapter to canonical tie-in capacity allocation
FacilityDesignResult Installed sizing basis, detailed constraints, power and parallel-train indication
FacilityModificationPlanner / FacilityModificationPlan Traceable annual debottleneck candidates and screening capacity targets
FieldProductionPotentialProvider Pluggable detailed wells/network, reservoir schedule or surrogate potential
FieldProductSpecifications Contractual gas/oil export and produced-water discharge limits
ProductSpecificationEvaluator Live stream quality measurements and annual compliance result
FieldProductQualityProvider Adapter for real process analysers and water-treatment models
FieldLifecycleModel Explicit connection points between reservoir, process, export and injection streams
FieldLifecycleConcept Links the existing FieldConcept design basis to an executable model
FieldLifecycleSimulator Time-marches process and reservoir state and creates annual profiles
FieldLifecycleResult Annual profiles plus NPV, IRR, payback, break-even, energy and CO2
FieldLifecycleEvaluator Runs and ranks alternative concepts by NPV
AreaDevelopmentOption / AreaDevelopmentPortfolio Greenfield and multi-host route definitions
AreaDevelopmentEvaluator / AreaDevelopmentResult Eligible area ranking and comparison table
NorwegianOilFieldCase Repeatable synthetic NCS oil/gas-injection reference case

Start with ConceptEvaluator for rapid multi-concept screening. Promote the promising options to FieldLifecycleConcept models, run the physically coupled lifetime comparison, and then replace uncertain screening assumptions with PVT studies, well tests, reservoir schedules and equipment design results as the project matures.

The implementation follows the traceable building-block and computational workflow in Field Development and Operations: A Computational Approach with NeqSim - TPG4230 NTNU (Solbraa et al., 1st ed., 2026), particularly the separation of reservoir, wells, SURF, facility, export, schedule and economic evidence. The synthetic reference results remain independent teaching assumptions and do not reproduce a named asset or confidential study.