gas_rate_linear
Calculate gas production rates for horizontal wells using real gas pseudopressure to account for pressure-dependent gas properties like Z-factor and viscosity variations.
Instructions
Calculate gas production rate for linear flow.
INFLOW PERFORMANCE TOOL - Computes gas production rate for horizontal wells or wells with linear 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.
area (float, required): Cross-sectional flow area in square feet. Must be > 0. Typical: 100-10000 ft². Example: 1000.0.
length (float, required): Flow length in feet. Must be > 0. Typical: 100-5000 ft. Example: 500.0.
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.
Flow Geometry: Linear flow occurs in:
Horizontal wells (early-time flow)
Hydraulically fractured vertical wells (fracture flow)
Channelized gas reservoirs
Edge water drive systems
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 (Linear): qg = (k × area × (m(pi) - m(pwf))) / (1422 × T × length)
Where PVT properties are integrated over pressure range.
Linear vs Radial Flow:
Linear: Flow perpendicular to wellbore (horizontal wells)
Radial: Flow converging to wellbore (vertical wells)
Linear flow typically has higher productivity than radial
Returns: Dictionary with:
value (float or list): Gas rate in MSCF/day (matches input psd shape)
method (str): "Pseudopressure linear 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)
Confusing flow area (perpendicular to flow) with wellbore area
Using wrong flow length (should be distance from boundary to well)
Confusing linear flow (horizontal wells) with radial flow (vertical wells)
Not accounting for net pay thickness correctly
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. Linear flow is characteristic of horizontal wells and hydraulically fractured wells.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| request | Yes |
Input Schema (JSON Schema)
Implementation Reference
- The MCP tool handler function 'gas_rate_linear' that processes the request, calls the underlying pyrestoolbox.gas.gas_rate_linear computation for linear gas flow using pseudopressure method, formats the output, and returns a dictionary with value, method, units, and inputs.@mcp.tool() def gas_rate_linear(request: GasRateLinearRequest) -> dict: """Calculate gas production rate for linear flow. **INFLOW PERFORMANCE TOOL** - Computes gas production rate for horizontal wells or wells with linear 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. - **area** (float, required): Cross-sectional flow area in square feet. Must be > 0. Typical: 100-10000 ft². Example: 1000.0. - **length** (float, required): Flow length in feet. Must be > 0. Typical: 100-5000 ft. Example: 500.0. - **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. **Flow Geometry:** Linear flow occurs in: - Horizontal wells (early-time flow) - Hydraulically fractured vertical wells (fracture flow) - Channelized gas reservoirs - Edge water drive systems **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 (Linear):** qg = (k × area × (m(pi) - m(pwf))) / (1422 × T × length) Where PVT properties are integrated over pressure range. **Linear vs Radial Flow:** - Linear: Flow perpendicular to wellbore (horizontal wells) - Radial: Flow converging to wellbore (vertical wells) - Linear flow typically has higher productivity than radial **Returns:** Dictionary with: - **value** (float or list): Gas rate in MSCF/day (matches input psd shape) - **method** (str): "Pseudopressure linear 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) - Confusing flow area (perpendicular to flow) with wellbore area - Using wrong flow length (should be distance from boundary to well) - Confusing linear flow (horizontal wells) with radial flow (vertical wells) - Not accounting for net pay thickness correctly **Example Usage:** ```python { "pi": 5000.0, "sg": 0.7, "degf": 180.0, "psd": [2000, 3000, 4000], "h": 50.0, "k": 100.0, "area": 1000.0, "length": 500.0, "h2s": 0.0, "co2": 0.0, "n2": 0.0 } ``` 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. Linear flow is characteristic of horizontal wells and hydraulically fractured wells. """ # Convert psd to numpy array for processing psd_array = np.asarray(request.psd) is_scalar = psd_array.ndim == 0 if is_scalar: psd_array = np.array([psd_array]) # Call gas_rate_linear with correct parameters qg = gas.gas_rate_linear( k=request.k, pr=request.pi, pwf=psd_array, area=request.area, length=request.length, degf=request.degf, sg=request.sg, h2s=request.h2s, co2=request.co2, n2=request.n2, ) # Convert numpy array to list for JSON serialization if isinstance(qg, np.ndarray): value = qg.tolist() else: value = float(qg) return { "value": value, "method": "Pseudopressure linear flow", "units": "MSCF/day", "inputs": request.model_dump(), }
- Pydantic model 'GasRateLinearRequest' defining and validating all input parameters for the gas_rate_linear tool, including pressures, fluid properties, reservoir dimensions, and non-hydrocarbon fractions.class GasRateLinearRequest(BaseModel): """Request model for linear gas inflow performance calculation.""" pi: float = Field(..., gt=0, description="Initial reservoir pressure (psia)") sg: float = Field( ..., ge=0.5, le=2.0, description="Gas specific gravity (air=1, dimensionless)" ) degf: float = Field( ..., gt=-460, lt=1000, description="Temperature (degrees Fahrenheit)" ) psd: Union[float, List[float]] = Field( ..., description="Sandface pressure (psia) - scalar or array" ) h: float = Field(..., gt=0, description="Net pay thickness (ft)") k: float = Field(..., gt=0, description="Permeability (mD)") area: float = Field(..., gt=0, description="Drainage area (sq ft)") length: float = Field(..., gt=0, description="Well length (ft)") h2s: float = Field( 0.0, ge=0.0, le=1.0, description="H2S mole fraction (dimensionless)" ) co2: float = Field( 0.0, ge=0.0, le=1.0, description="CO2 mole fraction (dimensionless)" ) n2: float = Field( 0.0, ge=0.0, le=1.0, description="N2 mole fraction (dimensionless)" ) @field_validator("psd") @classmethod def validate_pressure(cls, v): """Validate pressure values.""" if isinstance(v, list): if not all(p > 0 for p in v): raise ValueError("All sandface pressure values must be positive") else: if v <= 0: raise ValueError("Sandface pressure must be positive") return v
- src/pyrestoolbox_mcp/server.py:18-26 (registration)The registration of inflow tools (including gas_rate_linear) by importing and calling register_inflow_tools on the FastMCP server instance in the main server module.from .tools.inflow_tools import register_inflow_tools from .tools.simtools_tools import register_simtools_tools from .tools.brine_tools import register_brine_tools from .tools.layer_tools import register_layer_tools from .tools.library_tools import register_library_tools register_oil_tools(mcp) register_gas_tools(mcp) register_inflow_tools(mcp)
- src/pyrestoolbox_mcp/tools/inflow_tools.py:21-21 (registration)The registration function that defines and registers the gas_rate_linear tool using @mcp.tool() decorator when called.def register_inflow_tools(mcp: FastMCP) -> None: