Horner Plot Pressure Transient Analysis Calculator

Compute formation permeability-thickness ($k \cdot h$), near-wellbore skin factor ($s$), and extrapolated initial pressure ($p^*$) from semilog Pressure Buildup Tests (PBT).

Buildup Test & Production Data

Producing Time t_p (hours): t_p = 24 · N_p / q_last

Flow Rate Before Shut-in q (stb/d):

Semilog Slope m (psi/cycle):

Extrapolated 1-hr Press p_1hr (psi):

Flowing BHP at Shut-in p_wf(0) (psi):

Net Pay Thickness h (ft):

Porosity φ (fraction):

Total Compressibility c_t (psi⁻¹):

Oil Viscosity μ (cP):

Wellbore Radius r_w (ft):

Permeability & Skin Results

Formation Permeability (k)

Wellbore Skin Factor (s)

Skin Drop Δp_s

Flow Efficiency FE

Radius of Invest. r_i

Horner Straight-Line Interpretation

m = 162.6 · q · B · μ / (k · h) | Extrapolated at (tp + Δt)/Δt = 1

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Horner Plot Pressure Transient Analysis Calculator

Buildup Test & Production Data

Permeability & Skin Results

Frequently Asked Questions