Calculations & Equations

Equations Hub

All essential well testing equations with interactive calculators.

Radial Flow Equation (Drawdown)

▾

p(r) = pᵢ − (162.6 q B μ / (k h)) [ log₁₀ (k t / (φ μ cₜ r²)) + s ]

Flow Rate q (STB/d)

μ (cp)

k (md)

h (ft)

Slope (m)

52.03 psi/cycle

Horner Time Ratio

▾

Horner Time = (tₚ + Δt) / Δt

Production Time (hr)

Shut-in Time (hr)

Horner Time

11.00 dimensionless

Permeability from Semi-Log Slope

▾

k = (162.6 q B μ) / (m h)

Flow Rate q (STB/d)

μ (cp)

Slope m (psi/cycle)

h (ft)

Permeability (k)

50.03 md

Engineering calculators and conversion utilities for field work.

⇄ Unit Converter

Value

From

Result

6894.7600 kPa

⦿ Skin Factor Estimator

P1hr (psi)

Pwf (psi)

Slope m (psi/cycle)

k/(φμct rw²)

Skin Factor (S)

3.45 Slight damage

⏱ Horner Time Calculator

Production Time tp (hr)

Shut-in Time Δt (hr)

Horner Time Ratio

11.000 log10 = 1.0414