Well Test Design

Calculate test duration, gauge resolution, and expected pressure change from reservoir parameters.

Reservoir & Well Parameters

Permeability, k (mD)

Net Pay, h (ft)

Flow Rate, q (STB/d)

Viscosity, μ (cp)

FVF, B (rb/STB)

Total Compressibility, c_t (1/psi)

Wellbore Radius, r_w (ft)

Porosity, φ (fraction)

Drainage Radius, r_e (ft)

ΔP = (162.6 × q × B × μ) / (k × h) × [log(t) + log(k/(φμc_tr_w²)) - 3.23]

Expected ΔP @ 24 hr

Min Test Duration

Recommended Gauge Res.

Wellbore Storage Coeff.

WBS Duration

Radius of Investigation @ 24h

Semilog Slope (m)

How this works

ΔP: Calculated using the line-source (Ei) solution approximation for radial flow (Horner/MTR analysis).

Min test duration: Time to end wellbore storage effects: t_min = (200,000 × C_s) / (k × h / μ), where C_s = wellbore storage coefficient.

Gauge resolution: Recommended as ΔP/1000 to resolve the pressure transient over the test.

Radius of investigation: r_inv = 0.029 × sqrt(k × t / (φ × μ × c_t)).

Need help designing pressure transient tests or interpreting buildup data?