Miscible and surfactant EOR

PetroScript models miscible displacement and surfactant viscosity as semantic physics intent. Users describe the reservoir behavior they want; compiler lowerers own backend card details.

Miscible package

Attach miscible behavior to a model’s physics=[...] with ps.miscible.Package(...). The package composes with ps.solvent.Package(...) when the chosen miscibility behavior depends on an explicit solvent package; solvent activation and solvent property data remain owned by the solvent namespace.

import petroscript as ps

base = ps.Model(
    name="BASE",
    units="field",
    start="2020-01-01",
    grid=ps.grid.Cartesian(shape=(2, 2, 1), dx=500.0, dy=500.0, dz=40.0, top=2500.0),
    rock=ps.Rock(porosity=0.25, permeability=100.0, vertical_ratio=1.0),
    fluid=ps.fluid.OilWater(
        oil=ps.pvt.DeadOil(pressure=[14.7, 3500.0], oil_fvf=[1.06, 1.0], oil_viscosity=[1.0, 1.2]),
        water=ps.pvt.Water(
            reference_pressure=3000.0,
            fvf=1.0,
            compressibility=3.0e-6,
            viscosity=0.5,
            viscosibility=0.0,
        ),
        oil_surface_density=53.0,
        water_surface_density=64.0,
    ),
    relperm=[ps.relperm.OilWater(sw=[0.20, 0.80], krw=[0.0, 1.0], krow=[1.0, 0.0], pcow=[0.0, 0.0])],
    initial=ps.initial.Equilibrium(
        datum_depth=2520.0, datum_pressure=3000.0, oil_water_contact=2600.0, gas_oil_contact=0.0
    ),
    wells=[ps.Well(name="PROD1", i=1, j=1)],
    schedule=ps.Schedule(
        report=[ps.Every(30.0)],
        events=[
            ps.Event(
                "2020-01-01",
                ps.Perforate(well="PROD1", k=(1, 1), diameter=0.3),
                ps.Produce(well="PROD1", oil_rate=220.0, bhp_limit=1200.0),
            )
        ],
    ),
)

solvent = ps.solvent.Package(
    density=45.0,
    pvt=ps.solvent.PVT(
        rows=[
            {"pressure": 14.7, "fvf": 1.0, "viscosity": 0.1},
            {"pressure": 3500.0, "fvf": 0.9, "viscosity": 0.2},
        ]
    ),
)

miscible = ps.miscible.Package(
    transform=ps.miscible.Transform(
        rows=[
            {"solvent_fraction": 0.0, "miscibility": 0.0},
            {"solvent_fraction": 1.0, "miscibility": 1.0},
        ]
    ),
    pressure_miscibility=ps.miscible.PressureCurve(
        rows=[
            {"pressure": 1500.0, "miscibility": 0.0},
            {"pressure": 3500.0, "miscibility": 1.0},
        ]
    ),
    normalized_relperm=ps.miscible.RelPerm(
        rows=[
            {"total_gas_saturation": 0.0, "gas_relperm": 0.0, "oil_relperm": 1.0},
            {"total_gas_saturation": 1.0, "gas_relperm": 1.0, "oil_relperm": 0.0},
        ]
    ),
    residual_oil=ps.miscible.ResidualOil(
        rows=[
            {"water_saturation": 0.0, "residual_oil_saturation": 0.0},
            {"water_saturation": 1.0, "residual_oil_saturation": 0.30},
        ]
    ),
    critical_gas=ps.miscible.CriticalGas(
        rows=[
            {"water_saturation": 0.0, "critical_gas_saturation": 0.0},
            {"water_saturation": 1.0, "critical_gas_saturation": 0.03},
        ]
    ),
    todd_longstaff=ps.miscible.Mixing(
        regions={1: {"viscosity_parameter": 0.60, "density_parameter": 0.60}}
    ),
)

model = base.replace(
    physics=[solvent, miscible],
    regions=ps.Regions(miscible=1),  # every cell in miscible region 1 (MISCNUM)
)

Canonical classes (each table’s rows are mappings by column name, or sequences in the columns’ order):

• ps.miscible.Package
• ps.miscible.Transform
• ps.miscible.PressureCurve
• ps.miscible.RelPerm
• ps.miscible.ResidualOil
• ps.miscible.CriticalGas
• ps.miscible.Mixing

Surfactant viscosity intent

Surfactant viscosity is represented as typed intent under ps.surfactant, but current native simulator evidence blocks executable surfactant activation. The semantic API is still useful because it fails closed with a stable diagnostic instead of silently writing a deck that the simulator will reject.

surfactant = ps.surfactant.Package(
    viscosity=ps.surfactant.Viscosity(
        rows=[
            {"concentration": 0.0, "viscosity": 1.0},
            {"concentration": 1.0, "viscosity": 2.0},
        ]
    )
)

ps.testing.assert_issue(
    lambda: base.replace(physics=[surfactant]),
    code="surfactant.flow.activation_unsupported",
)

Canonical classes:

• ps.surfactant.Package
• ps.surfactant.Viscosity

API law

• Do not author raw backend cards directly.
• Keep solvent package data under ps.solvent; miscible APIs may depend on it but must not duplicate it.
• Treat surfactant support as fail-closed until a future slice records native simulator evidence for a runnable activation path.