Decline Diagnostics Functions
Loss-ratio derivatives and D(t) functions for identifying the governing decline model.
13 functions
PO.DCA.Diag.Bourdet
Calculates the Bourdet (smoothed) derivative at point t. Used for flow regime identification and production diagnostics.
PO.DCA.Diag.Bourdet.SemiLog
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.
PO.DCA.Diag.Beta
Computes the beta diagnostic β = t×D(t) for flow regime identification. β≈0.5: linear flow, β≈0.25: bilinear, β≈1.0: boundary-dominated.
PO.DCA.Diag.bParam
Computes the time-varying Arps b-parameter. b=0: exponential, 0<b<1: hyperbolic, b=1: harmonic, b>1: transient (unconventional).
PO.DCA.Arps.D
Calculates instantaneous decline rate D(t) for Arps decline, {1/T}. D(t) = Di/(1+b×Di×t). Computed numerically.
PO.DCA.ModHyp.D
Calculates instantaneous decline rate D(t) for Modified Hyperbolic decline, {1/T}. Computed numerically.
PO.DCA.PLE.D
Calculates instantaneous decline rate D(t) for Power Law Exponential (PLE) model, {1/T}. D(t) = D∞ + n×Di0×t^(n-1). Computed numerically.
PO.DCA.SEDM.D
Calculates instantaneous decline rate D(t) for Stretched Exponential model, {1/T}. D(t) = (n/τ)×(t/τ)^(n-1). Computed numerically.
PO.DCA.EEDM.D
Calculates instantaneous decline rate D(t) for Extended Exponential Decline Model (EEDM), {1/T}. Computed analytically.
PO.DCA.Duong.D
Calculates instantaneous decline rate D(t) for Duong model, {1/T}. Computed numerically.
PO.DCA.LGM.D
Calculates instantaneous decline rate D(t) for Logistic Growth Model (LGM), {1/T}. Computed analytically.
PO.DCA.THM.D
Calculates instantaneous decline rate D(t) for Transient Hyperbolic Model, {1/T}. Computed analytically.
PO.DCA.AKB.D
Calculates instantaneous decline rate D(t) for Ansah-Knowles-Buba (2000) decline, {1/T}. Computed numerically.