pyResToolbox MCP Server

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

INFLOW PERFORMANCE TOOL - Computes gas production rate for vertical wells with radial flow geometry using real gas pseudopressure formulation. This accounts for pressure-dependent gas properties (Z-factor, viscosity) which are significant for gas systems. More accurate than simplified Darcy's law for gas.

Parameters:

• pi (float, required): Initial/reservoir pressure in psia. Must be > 0. Example: 5000.0.

• sg (float, required): Gas specific gravity (air=1). Valid: 0.55-3.0. Typical: 0.6-1.2. Example: 0.7.

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

• psd (float or list, required): Sandface/draining pressure(s) in psia. Must be > 0 and < pi. Can be scalar or array. Example: 2000.0 or [1000, 2000, 3000].

• 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.

• h2s (float, optional, default=0.0): H2S mole fraction (0-1). Typical: 0-0.05. Example: 0.0.

• co2 (float, optional, default=0.0): CO2 mole fraction (0-1). Typical: 0-0.20. Example: 0.0.

• n2 (float, optional, default=0.0): N2 mole fraction (0-1). Typical: 0-0.10. Example: 0.0.

Pseudopressure Method: Uses real gas pseudopressure (m(p)) which linearizes the gas diffusivity equation: m(p) = 2∫(p/(μZ))dp from pb to p

This accounts for:

• Z-factor variation with pressure

• Gas viscosity variation with pressure

• Non-linear pressure behavior

Flow Formula: qg = (kh × (m(pi) - m(pwf))) / (1422 × T × (ln(re/rw) + S))

Where PVT properties are integrated over pressure range.

Returns: Dictionary with:

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

• method (str): "Pseudopressure radial flow"

• units (str): "MSCF/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 accounting for non-hydrocarbon fractions (H2S, CO2, N2)

• 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: Gas rate decreases as sandface pressure increases (typical IPR curve).

Note: This tool uses pseudopressure method which is more accurate than simplified Darcy's law for gas. Always account for non-hydrocarbon components (H2S, CO2, N2) as they affect Z-factor and flow calculations significantly.