VFP export contract

EclipseVFPExporter formats supplied flowing bottomhole pressure at a specified well datum. It does not solve a well, infer BHP from a process outlet, convert mass flow to phase volume, or manufacture pressures for failed operating points.

Task API Meaning
Format supplied well pressures EclipseVFPExporter Validated deck structure and unit conversion; physical BHP qualification belongs to the caller
Calculate process pressure requirements LiftCurveGenerator.generateTable() and MultiScenarioVFPGenerator.generateVFPTable() Required process inlet pressure for configured outlet conditions; a generic pipeline/facility result is not automatically well BHP
Screen fixed-composition capacity ProcessOptimizationEngine.generateCapacityScreening() Maximum mass throughput at pressure/temperature combinations; no composition recombination or BHP
Inspect process capacity/lift results FlowRateOptimizer table toJson(), toCsv() where available, or toFormattedString() Process inlet/outlet pressures, mass flow, power and feasibility

A qualified well VFP calculation must separately establish the well geometry and datum, hydrostatic and frictional pressure losses, thermal boundary conditions, fluid composition and recombination at each water/gas ratio, lift-gas injection, the standard phase-volume rate basis, solver convergence, constraints, and an independent hydraulic benchmark. The exporter cannot certify these conditions. Generic process generators remain screening tools until the caller establishes that complete well-model contract.

Supported deck representation

The production format follows the public OPM implementation of the Eclipse VFPPROD keyword. The header has nine positions:

table number, datum depth, rate type, water ratio type, gas ratio type, THP, ALQ type, units, BHP.

The five axis records are flow, THP, water ratio, gas ratio and ALQ. Each pressure row starts with one-based THP, water-ratio, gas-ratio and ALQ indices, followed by one BHP for each flow-axis value. The Java input array has a different order: [flow][THP][water ratio][gas ratio][ALQ]. Every supplied cell is written exactly once.

Definition Supported values
Production rate OIL, LIQ (oil + water), GAS
Water ratio WCT (water/liquid), WOR (water/oil), WGR (water/gas)
Gas ratio GOR (gas/oil), GLR (gas/liquid), OGR (oil/gas)
Artificial lift Empty type with a singleton zero axis, or GRAT with supplied gas-lift rates
Output units METRIC, FIELD; must match the surrounding OPM deck
Injection VFPINJ, rate type OIL, WAT or GAS, singleton zero water/gas/ALQ axes

VFPINJ writes a six-position header (table, datum, rate, THP, units, BHP), flow and THP axes, then rows prefixed by the one-based THP index. Nonzero or multiple composition/lift axes are rejected for injection rather than discarded. No VFPEXP export-system dialect is supported by EclipseVFPExporter.

Input and output units

The default input units are Sm3/day and bara, regardless of output unit system. setInputUnits(rateUnit, pressureUnit) accepts Sm3/day, Sm3/hr or Sm3/s, and bara, Pa or psia. It applies to flow, THP and BHP. The other input conventions remain metres TVD for datum, Sm3/Sm3 for ratios, and Sm3/day for GRAT.

Standard volumes must already use the surface reference conditions of the reservoir model. A geometric unit conversion does not change the reference temperature or pressure.

Quantity METRIC output FIELD output FIELD conversion from canonical metric input
Datum m ft m / 0.3048
Absolute THP/BHP bara psia bara × 100000 / 6894.757293168
OIL/LIQ/WAT rate Sm3/day STB/day Sm3/day / 0.158987294928
GAS rate, GRAT Sm3/day Mscf/day Sm3/day / 28.316846592
GOR/GLR Sm3/Sm3 Mscf/STB ratio × 0.158987294928 / 28.316846592
WGR/OGR Sm3/Sm3 STB/Mscf ratio × 28.316846592 / 0.158987294928
WCT/WOR volume fraction/ratio volume fraction/ratio unchanged

In FIELD VFP tables, GOR uses Mscf/STB, not scf/STB. Multiplying by 1000 would misstate the composition axis. Mass rates (kg/hr), actual volume rates, gauge pressures, SI as an output deck keyword and unsupported lift definitions fail explicitly.

Validation and infeasible points

All axes must be nonempty, finite, nonnegative and strictly increasing; THP must be positive. WCT is bounded by 0 and 1. Omitted composition and ALQ axes default to singleton zero, but an explicitly empty array is invalid. Every BHP dimension must match its axis, and all cells must contain finite positive absolute pressure.

NaN, infinity, zero BHP, ragged or dimensionally mismatched arrays, missing cells and unsupported definitions are rejected before an export opens its destination. Invalid data never become 1*, copied neighbors or empirical fallback pressures. Infeasible results can be retained in diagnostic tables; select a fully feasible grid before requesting a deck. Transposing equally sized dimensions cannot be detected from array shape; callers must preserve the documented axis order.

Migration from legacy methods

The executable supplied-BHP example and exporter API example illustrate the supported setup. Their synthetic pressures demonstrate serialization, not well physics.

Independent validation

EclipseVFPExporterContractTest parses slash-delimited records independently of the exporter and compares every axis/index/value with hand-authored METRIC, FIELD and injection fixtures. It also checks unit factors separately, input-unit conversion, nonzero composition and multiple lift values, invalid data, precision, locale and destination-file preservation. CapacityScreeningSemanticsTest checks fixed composition, applied temperatures, pressure feasibility and rejection of process-to-BHP mappings.

This is deck-contract validation, not execution in Eclipse or OPM Flow. The fixture provenance and sources record the public OPM keyword schema, parser and unit definitions. Before a reservoir study, load the generated include in the target simulator and validate the physical well model.

Primary references: OPM VFPPROD schema, VFPProdTable parser, OPM unit definitions.