PO.DCA.Diag.Bourdet.SemiLog
Description
Calculates the classical Bourdet derivative dy/d(ln x) at point t, the log-domain estimator used for semilog and log-log well-test analysis. Multiply by LN(10) for a slope per log cycle.
Syntax
=PO.DCA.Diag.Bourdet.SemiLog(x_values, y_values, t, L)Parameters
| Parameter | Description |
|---|---|
| x_values | Sample points, sorted ascending. Pass the raw abscissa - time, or Horner time - never its logarithm; the log is taken internally. |
| y_values | Sample values (pressure, rate, or cumulative production). |
| t | Point at which to calculate derivative, in the same x as x_values. |
| L | Smoothing window in natural-log cycles of x: the least separation in ln(x) a neighbour must have from t to be used. L=0 uses adjacent points. Typical: 0.1-0.5. It only engages where the data is sampled finer than L. Requires x>0. |