welltest_pta.horner_extrapolation
- welltest_pta.horner_extrapolation(p, t_hr, tp_hr, fit_start_frac=0.30, fit_end_frac=0.85)[source]
Linear regression of \(p_{ws}\) vs Horner time on the IARF window.
- Parameters:
p (
ndarray) – Shut-in pressure (smoothed) over the buildup, length \(n_b\).t_hr (
ndarray) – Elapsed time in hours (any reference; only differences matter).tp_hr (
float) – Producing time before shut-in (hr). For a Horner plot this is the duration of the immediately preceding drawdown.fit_start_frac (
float) – Fractional positions along the buildup that delimit the infinite-acting straight line. Defaults skip the early wellbore-storage transition (≤30 %) and the late boundary deviation (≥85 %).fit_end_frac (
float) – Fractional positions along the buildup that delimit the infinite-acting straight line. Defaults skip the early wellbore-storage transition (≤30 %) and the late boundary deviation (≥85 %).
- Return type:
- Returns:
dict with keys
- ``p_star`` (extrapolated pressure at \((t_p+\\Delta t)/\\Delta t = 1\))
- ``slope_m`` (Horner slope (psi / log-cycle), used for
kh)- ``r2`` (coefficient of determination on the fit window)
- ``fit_start_idx``, ``fit_end_idx`` (indices of fit window)