pyResToolbox MCP Server

Calculate oil production rate for radial flow (vertical well).

INFLOW PERFORMANCE TOOL - Computes oil production rate for vertical wells with radial flow geometry using Darcy's law. Automatically calculates PVT properties (Rs, Bo, μo) at average pressure. Optionally applies Vogel IPR model for two-phase flow below bubble point.

Parameters:

• pi (float, required): Initial/reservoir pressure in psia. Must be > 0. Example: 4000.0.

• pb (float, required): Bubble point pressure in psia. Must be ≥ 0. Example: 3500.0. If pi < pb, reservoir is saturated (gas cap present).

• api (float, required): Oil API gravity in degrees. Valid: 0-100. Example: 35.0.

• degf (float, required): Reservoir temperature in °F. Valid: -460 to 1000. Example: 180.0.

• sg_g (float, required): Gas specific gravity (air=1). Valid: 0-3. Typical: 0.6-1.2. Example: 0.75.

• psd (float or list, required): Sandface/draining pressure(s) in psia. Must be > 0 and < pi. Can be scalar or array. Example: 1500.0 or [1000, 1500, 2000].

• h (float, required): Net pay thickness in feet. Must be > 0. Typical: 10-200 ft. Example: 50.0.

• k (float, required): Permeability in millidarcies (mD). Must be > 0. Typical: 1-1000 mD. Example: 100.0.

• s (float, optional, default=0.0): Skin factor (dimensionless). Negative = stimulation, positive = damage. Typical: -5 to +20. Example: 0.0 for undamaged well.

• re (float, required): Drainage radius in feet. Must be > rw. Typical: 500-5000 ft. Example: 1000.0.

• rw (float, required): Wellbore radius in feet. Must be > 0. Typical: 0.25-0.5 ft. Example: 0.5.

• rsb (float, required): Solution GOR at bubble point in scf/stb. Must be ≥ 0. Example: 800.0.

• vogel (bool, optional, default=False): Apply Vogel IPR model. Set True when pi < pb (saturated reservoir). Example: False.

Flow Regime:

• Undersaturated (pi > pb): Single-phase oil flow, Darcy's law applies

• Saturated (pi < pb): Two-phase flow, use Vogel=True for accurate IPR

Darcy's Law Formula: qo = (0.00708 × k × h × (pi - pwf)) / (μo × Bo × (ln(re/rw) + S))

Where PVT properties (μo, Bo) are calculated at average pressure (pi + pwf)/2.

Returns: Dictionary with:

• value (float or list): Oil rate in STB/day (matches input psd shape)

• method (str): "Darcy radial flow" or "Vogel IPR"

• units (str): "STB/day"

• inputs (dict): Echo of input parameters

Common Mistakes:

• Using separator temperature instead of reservoir temperature

• Pressure in barg/psig instead of psia (must be absolute)

• Not setting vogel=True when pi < pb (underestimates rate)

• Using wrong drainage radius (re) - should be well spacing/2

• Confusing net pay (h) with gross thickness

• Not accounting for skin factor (s)

Example Usage:

Result: Oil rate decreases as sandface pressure increases (typical IPR curve).

Note: This tool automatically calculates PVT properties. You don't need to provide Rs, Bo, or μo - they are computed internally at average pressure. For saturated reservoirs (pi < pb), set vogel=True for accurate two-phase flow.