generate_rel_perm_table

Generate relative permeability table for reservoir simulation.

CRITICAL SIMULATION TOOL - Creates saturation-dependent relative permeability curves for ECLIPSE, Intersect, CMG, or other simulators. Relative permeability is essential for multiphase flow simulation and determines fluid mobility.

Parameters:

• rows (int, required): Number of saturation points in table. Must be > 0. Typical: 20-50. Example: 25. More rows = smoother curves but larger files.

• krtable (str, required): Table type. Options: "SWOF", "SGOF", "SGWFN". Example: "SWOF" for water-oil systems.

• krfamily (str, required): Correlation family. Options: "COR" (Corey), "LET". Example: "COR" for simple power-law, "LET" for flexible fitting.

• kromax (float, required): Maximum oil relative permeability (0-1). Typical: 0.5-1.0. Example: 1.0.

• swc (float, required): Connate water saturation (0-1). Must be < 1. Typical: 0.1-0.3. Example: 0.15.

• krwmax (float, optional): Maximum water rel perm for SWOF (0-1). Typical: 0.1-0.5. Example: 0.25.

• krgmax (float, optional): Maximum gas rel perm for SGOF/SGWFN (0-1). Typical: 0.5-1.0. Example: 1.0.

• sorw (float, optional): Residual oil saturation to water (0-1). Typical: 0.1-0.3. Example: 0.15.

• sorg (float, optional): Residual oil saturation to gas (0-1). Typical: 0.05-0.2. Example: 0.1.

• sgc (float, optional): Critical gas saturation (0-1). Typical: 0.05-0.15. Example: 0.1.

• swcr (float, optional): Critical water saturation for Corey (0-1). Typical: 0.15-0.25. Example: 0.2.

• no (float, optional): Corey exponent for oil (Corey only). Must be > 0. Typical: 2.0-4.0. Example: 2.5. Higher = more curved.

• nw (float, optional): Corey exponent for water (Corey only). Must be > 0. Typical: 1.5-3.0. Example: 1.5.

• ng (float, optional): Corey exponent for gas (Corey only). Must be > 0. Typical: 2.0-3.5. Example: 2.0.

• Lo, Eo, To (float, optional): LET parameters for oil (LET only). Typical: Lo=1-3, Eo=1-2, To=1-3. Example: Lo=2.5, Eo=1.25, To=1.75.

• Lw, Ew, Tw (float, optional): LET parameters for water (LET only). Typical: Lw=1-3, Ew=1-2, Tw=1-3. Example: Lw=1.5, Ew=1.0, Tw=2.0.

• Lg, Eg, Tg (float, optional): LET parameters for gas (LET only). Typical: Lg=1-3, Eg=1-2, Tg=1-3. Example: Lg=1.2, Eg=1.5, Tg=2.0.

Correlation Families:

• Corey (1954): Simple power-law model, fast, widely used. Formula: Kr = krmax * ((S - Sc) / (1 - Swc - Sor))^n Use for: Quick estimates, standard cases, compatibility.

• LET (2005): Flexible 3-parameter model, better curve fitting. Formula: Kr = krmax * (S^L) / (S^L + E * (1-S)^T) Use for: History matching, complex curves, accuracy.

Table Types:

• SWOF: Water-Oil (waterflood, aquifer influx). Columns: Sw, Krw, Kro, Pcow.

• SGOF: Gas-Oil (gas cap expansion, gas injection). Columns: Sg, Krg, Krog, Pcog.

• SGWFN: Three-phase gas-water (gas cycling, WAG). Columns: Sg, Krg, Krw, Pcog, Pcow.

Saturation Endpoints:

• Swc: Connate water (immobile water)

• Sorw: Residual oil to water (trapped oil after waterflood)

• Sorg: Residual oil to gas (trapped oil after gas injection)

• Sgc: Critical gas (minimum gas saturation for flow)

Workflow:

1. Choose correlation family (Corey or LET)

2. Select table type (SWOF, SGOF, SGWFN)

3. Specify saturation endpoints (Swc, Sor, Sgc)

4. Set maximum rel perms (kromax, krwmax, krgmax)

5. Define correlation parameters (Corey exponents or LET params)

6. Generate table with specified number of rows

Returns: Dictionary with:

• table (list): List of dicts with saturation and rel perm values

• columns (list): Column names (e.g., ["Sw", "Krw", "Kro", "Pcow"])

• rows (int): Number of rows in table

• table_type (str): Table type (SWOF, SGOF, SGWFN)

• correlation (str): Correlation family (COR, LET)

• note (str): Usage guidance

• inputs (dict): Echo of input parameters

Common Mistakes:

• Saturation endpoints don't sum correctly (Swc + Sor < 1.0)

• Using wrong table type for simulation (check simulator requirements)

• Corey exponents too high (>5) causing unrealistic curves

• Not specifying required parameters for chosen table type

• Too few rows (<10) causing poor curve resolution

• Maximum rel perms > 1.0 (must be dimensionless 0-1)

Example Usage (Corey SWOF):

{
    "rows": 25,
    "krtable": "SWOF",
    "krfamily": "COR",
    "kromax": 1.0,
    "krwmax": 0.25,
    "swc": 0.15,
    "swcr": 0.2,
    "sorw": 0.15,
    "no": 2.5,
    "nw": 1.5
}

Example Usage (LET SGOF):

{
    "rows": 25,
    "krtable": "SGOF",
    "krfamily": "LET",
    "kromax": 1.0,
    "krgmax": 1.0,
    "swc": 0.2,
    "sorg": 0.15,
    "sgc": 0.1,
    "Lo": 2.5,
    "Eo": 1.25,
    "To": 1.75,
    "Lg": 1.2,
    "Eg": 1.5,
    "Tg": 2.0
}

Note: Relative permeability tables are critical for accurate simulation. Always validate endpoints against core data or literature. Use LET for history matching when Corey doesn't fit data well. Table format is ECLIPSE-compatible and ready for direct inclusion in simulation decks.