Joshi Horizontal Well Productivity Guide
A source-backed guide to the Joshi horizontal well productivity equation, drainage geometry, anisotropy, effective radius, skin, and the limits of steady-state inflow screening.
linked formula references
verified source links
Practical workflow
- 1
Define the completed horizontal length and a drainage geometry that matches the comparison case.
- 2
Enter horizontal and vertical permeability separately when anisotropy is known.
- 3
Use representative oil viscosity, formation volume factor, wellbore radius, and skin on one consistent unit basis.
- 4
Compare productivity index and rate at a stated drawdown, then test sensitivity to uncertain drainage, permeability, and skin inputs.
What the Joshi productivity index represents
Productivity index relates liquid rate to pressure drawdown. The Joshi formulation adapts this idea to horizontal-well geometry by representing flow toward the lateral through reservoir-scale and near-wellbore resistance terms.
The original work derives a horizontal-well productivity relationship from potential-fluid theory and discusses anisotropy and well eccentricity. PetroCalcHub exposes the individual geometry and resistance inputs so each assumption remains visible.
When to move beyond a screening equation
Use a calibrated analytical or numerical model when pressure changes with time, gas or water mobility becomes important, the well has multiple fractures, the lateral has material pressure loss, or reservoir boundaries cannot be represented by the selected drainage geometry.
For comparisons, keep pressure basis, PVT basis, permeability direction, completed length, and skin treatment consistent across cases. A larger calculated index is meaningful only when the same physical basis is used.
Start with these calculators
These links keep the guide close to the working calculator flow.