Migrating Functions from v1.8 to v2.0

Mapping of every v1.8 Excel UDF (213 functions across 7 categories) to its v2.0 equivalent (591 functions across 16 modules). v2.0 uses a dotted namespace (PO.<module>.<family>.<operation>) and groups thematically (e.g., Arps Exponential/Harmonic/Hyperbolic collapsed into one PO.DCA.Arps.* family with a b parameter). Migration notes flag only what actually changed: name (always renamed), parameter order, added/removed parameters, and unit changes.

Unit notation used below: [T] = time unit (days, months — consistent across inputs); [L3] = volume unit; [1/T] = nominal decline rate; [1/T^n] = PLE generalized decline rate (dimension varies with exponent n); rates in [bbl/D], [STB/d], [mscf/D] (thousand scf/day), [mmscf/D] (million scf/day); pressure in [psi] (absolute) or [psig] (gauge — flagged explicitly); temperature in [degF], [degR], [K]; viscosity in [cP]; IFT in [dynes/cm]; permeability in [mD]; dimensions [ft], [in]; formation volume factor [bbl/STB], [rcf/scf]; solution GOR [scf/STB].

When to use this doc

Open this document if, after upgrading from v1.8 to v2.0, your Excel sheets show #NAME? errors or formulas referencing the old UDF names. Ctrl-F your old function name, read the migration note, and update your formula.

How v2.0 names work

v2.0 uses a dotted namespace: PO.<module>.<family>.<operation>. Enter the full dotted name directly in a cell — Excel treats the dots as part of the identifier:

=PO.DCA.Arps.Rate(Qi, Di, b, time)

Parameter names in v2.0 use snake_case (pipe_ID, T_degF, SG_gas) where v1.8 used camelCase (pipeID, T, SGgas). This is cosmetic — Excel doesn't care about parameter names, only position.

Breaking changes — read first

Most v1.8 → v2.0 migrations are pure renames. Six cases require a real math or input change and will silently produce wrong numbers if you only rename:

Gas-flow rate unit flip (1000×) — ReynoldsNumberGas, InletPipePressureGas, OutletPipePressureGas: Qg was [mscf/d] (thousand scf/day), now [mmscf/D] (million scf/day). Divide old Qg values by 1000.
Arps Exponential and Harmonic collapse into unified Arps — ExponentialDecline* and HarmonicDecline* functions no longer exist; use PO.DCA.Arps.* with b=0 (exponential) or b=1 (harmonic).
Duong parameter reorder — v1.8 (a, m, q1, qInf, time) became v2.0 (q1, Qinf, a, m, time). Fit output order also reordered to [q1, qInf, a, m].
PLE Di0 dimension refinement — Di_intercept [1/T] → Di0 [1/T^n]. Old values may need recomputation depending on how they were calibrated.
Gauge vs absolute pressure in one PVT correlation — RsoDindorukChristman2001 took P in [psig]; v2.0 PO.PVT.Rs.ByDindorukChristman takes [psi] (absolute). Add ~14.7 psi.
Multiphase VFP parameter reorder — Beggs-Brill / Gray / Hagedorn-Brown .Pin / .Pout signatures were standardized; see the PipeFlow section for each rewrite.

Other unit wording changes ([STB/d] → [bbl/D], [psia] → [psi], [dymes/cm] → [dynes/cm]) are cosmetic — same number, relabeled.

Use the "On this page" sidebar to jump to a specific v1.8 category — Decline (54), PipeFlow (17), PTA (18), PVT (44), SCAL (38), Utilities (17), WellFlow (25).

Decline

All Arps (exponential, harmonic, hyperbolic) v1.8 functions collapse into a single PO.DCA.Arps.* family in v2.0 — the user now supplies b (0=exponential, 1=harmonic, 0<b<1=hyperbolic). Cumulative (*Cumulative) → *.Prod, EUR/Time unchanged semantically but econRate parameter renamed Q_econ. The new category also adds .D (instantaneous decline rate), .Diag.* (flow-regime diagnostics), .Convert.* (nominal/effective), and .Data.* (cleaning/outlier) families with no v1.8 equivalents. SSE/R2 statistics moved from Decline into a separate PO.Stats.* namespace.

Ansah-Knowles-Buba

Old (v1.8)	New (v2.0)	Migration notes
`AnsahKnowlesBubaDeclineRate(Qi, alpha, beta, time)`	`PO.DCA.AKB.Rate(Qi, alpha, beta, time)`	renamed
`AnsahKnowlesBubaDeclineCumulative(Qi, alpha, beta, time)`	`PO.DCA.AKB.Prod(Qi, alpha, beta, time)`	renamed
`AnsahKnowlesBubaDeclineEUR(Qi, alpha, beta, econRate)`	`PO.DCA.AKB.EUR(Qi, alpha, beta, Q_econ)`	renamed — parameter `econRate` → `Q_econ`
`AnsahKnowlesBubaDeclineTime(Qi, alpha, beta, econRate)`	`PO.DCA.AKB.Time(Qi, alpha, beta, Q_econ)`	renamed — parameter `econRate` → `Q_econ`
`AnsahKnowlesBubaDeclineFitParameters(timeValues, rateValues)`	`PO.DCA.AKB.Fit(times, rates)`	renamed
`AnsahKnowlesBubaDeclineWeightedFitParameters(timeValues, rateValues, weightsValues)`	`PO.DCA.AKB.WFit(times, rates, weights)`	renamed

Arps Exponential / Harmonic / Hyperbolic (now unified under `PO.DCA.Arps`)

Old (v1.8)	New (v2.0)	Migration notes
`ExponentialDeclineRate(Qi, Di, time)`	`PO.DCA.Arps.Rate(Qi, Di, b, time)`	renamed — added parameter `b` (pass `b=0`)
`ExponentialDeclineCumulative(Qi, Di, time)`	`PO.DCA.Arps.Prod(Qi, Di, b, time)`	renamed — added parameter `b` (pass `b=0`)
`ExponentialDeclineEUR(Qi, Di, econRate)`	`PO.DCA.Arps.EUR(Qi, Di, b, Q_econ)`	renamed — added parameter `b` (pass `b=0`); parameter `econRate` → `Q_econ`
`ExponentialDeclineTime(Qi, Di, econRate)`	`PO.DCA.Arps.Time(Qi, Di, b, Q_econ)`	renamed — added parameter `b` (pass `b=0`); parameter `econRate` → `Q_econ`
`ExponentialDeclineFitParameters(timeValues, rateValues)`	`PO.DCA.Arps.Fit(times, rates)`	renamed — returns `[Qi, Di, b]` instead of `[Qi, Di]`
`ExponentialDeclineWeightedFitParameters(timeValues, rateValues, weightsValues)`	`PO.DCA.Arps.WFit(times, rates, weights)`	renamed — returns `[Qi, Di, b]` instead of `[Qi, Di]`
`HarmonicDeclineRate(Qi, Di, time)`	`PO.DCA.Arps.Rate(Qi, Di, b, time)`	renamed — added parameter `b` (pass `b=1`)
`HarmonicDeclineCumulative(Qi, Di, time)`	`PO.DCA.Arps.Prod(Qi, Di, b, time)`	renamed — added parameter `b` (pass `b=1`)
`HarmonicDeclineEUR(Qi, Di, econRate)`	`PO.DCA.Arps.EUR(Qi, Di, b, Q_econ)`	renamed — added parameter `b` (pass `b=1`); parameter `econRate` → `Q_econ`
`HarmonicDeclineTime(Qi, Di, econRate)`	`PO.DCA.Arps.Time(Qi, Di, b, Q_econ)`	renamed — added parameter `b` (pass `b=1`); parameter `econRate` → `Q_econ`
`HarmonicDeclineFitParameters(timeValues, rateValues)`	`PO.DCA.Arps.Fit(times, rates)`	renamed — returns `[Qi, Di, b]` instead of `[Qi, Di]`
`HarmonicDeclineWeightedFitParameters(timeValues, rateValues, weightsValues)`	`PO.DCA.Arps.WFit(times, rates, weights)`	renamed — returns `[Qi, Di, b]` instead of `[Qi, Di]`
`HyperbolicDeclineRate(Qi, Di, b, time)`	`PO.DCA.Arps.Rate(Qi, Di, b, time)`	renamed
`HyperbolicDeclineCumulative(Qi, Di, b, time)`	`PO.DCA.Arps.Prod(Qi, Di, b, time)`	renamed
`HyperbolicDeclineEUR(Qi, Di, b, econRate)`	`PO.DCA.Arps.EUR(Qi, Di, b, Q_econ)`	renamed — parameter `econRate` → `Q_econ`
`HyperbolicDeclineTime(Qi, Di, b, econRate)`	`PO.DCA.Arps.Time(Qi, Di, b, Q_econ)`	renamed — parameter `econRate` → `Q_econ`
`HyperbolicDeclineFitParameters(timeValues, rateValues)`	`PO.DCA.Arps.Fit(times, rates)`	renamed
`HyperbolicDeclineWeightedFitParameters(timeValues, rateValues, weightsValues)`	`PO.DCA.Arps.WFit(times, rates, weights)`	renamed

Modified Hyperbolic

Old (v1.8)	New (v2.0)	Migration notes
`ModifiedHyperbolicDeclineRate(Qi, Di, Dlim, b, time)`	`PO.DCA.ModHyp.Rate(Qi, Di, Dlim, b, time)`	renamed
`ModifiedHyperbolicDeclineCumulative(Qi, Di, Dlim, b, time)`	`PO.DCA.ModHyp.Prod(Qi, Di, Dlim, b, time)`	renamed
`ModifiedHyperbolicDeclineEUR(Qi, Di, Dlim, b, econRate)`	`PO.DCA.ModHyp.EUR(Qi, Di, Dlim, b, Q_econ)`	renamed — parameter `econRate` → `Q_econ`
`ModifiedHyperbolicDeclineTime(Qi, Di, Dlim, b, econRate)`	`PO.DCA.ModHyp.Time(Qi, Di, Dlim, b, Q_econ)`	renamed — parameter `econRate` → `Q_econ`
`ModifiedHyperbolicDeclineFitParameters(timeValues, rateValues)`	`PO.DCA.ModHyp.Fit(times, rates)`	renamed
`ModifiedHyperbolicDeclineWeightedFitParameters(timeValues, rateValues, weightsValues)`	`PO.DCA.ModHyp.WFit(times, rates, weights)`	renamed

Duong

Old (v1.8)	New (v2.0)	Migration notes
`DuongDeclineRate(a, m, q1, qInf, time)`	`PO.DCA.Duong.Rate(q1, Qinf, a, m, time)`	renamed — parameter order changed: was `(a, m, q1, qInf, time)`, now `(q1, Qinf, a, m, time)`
`DuongDeclineCumulative(a, m, q1, qInf, time)`	`PO.DCA.Duong.Prod(q1, Qinf, a, m, time)`	renamed — parameter order changed: was `(a, m, q1, qInf, time)`, now `(q1, Qinf, a, m, time)`
`DuongDeclineEUR(a, m, q1, qInf, econRate)`	`PO.DCA.Duong.EUR(q1, Qinf, a, m, Q_econ)`	renamed — parameter order changed (as above); parameter `econRate` → `Q_econ`
`DuongDeclineTime(a, m, q1, qInf, econRate)`	`PO.DCA.Duong.Time(q1, Qinf, a, m, Q_econ)`	renamed — parameter order changed (as above); parameter `econRate` → `Q_econ`
`DuongDeclineFitParameters(timeValues, rateValues)`	`PO.DCA.Duong.Fit(times, rates)`	renamed — fit now returns `[q1, qInf, a, m]` instead of `[a, m, q1, qInf]`
`DuongDeclineWeightedFitParameters(timeValues, rateValues, weightsValues)`	`PO.DCA.Duong.WFit(times, rates, weights)`	renamed — fit now returns `[q1, qInf, a, m]` instead of `[a, m, q1, qInf]`

Power Law Exponential (PLE)

Old (v1.8)	New (v2.0)	Migration notes
`PowerLawExponentialDeclineRate(Qi_intercept, Di_intercept, D_inf, n, time)`	`PO.DCA.PLE.Rate(Qi0, Di0, Dinf, n, time)`	renamed — parameters shortened; dimension of `Di0` refined from `[1/T]` to `[1/T^n]` (v1.8 label was inaccurate; numeric value unchanged if `Di` was calibrated consistently)
`PowerLawExponentialDeclineCumulative(Qi_intercept, Di_intercept, D_inf, n, time)`	`PO.DCA.PLE.Prod(Qi0, Di0, Dinf, n, time)`	renamed — parameters shortened; dimension of `Di0` refined from `[1/T]` to `[1/T^n]` (v1.8 label was inaccurate; numeric value unchanged if `Di` was calibrated consistently)
`PowerLawExponentialDeclineEUR(Qi_intercept, Di_intercept, D_inf, n, econRate)`	`PO.DCA.PLE.EUR(Qi0, Di0, Dinf, n, Q_econ)`	renamed — parameters shortened; dimension of `Di0` refined from `[1/T]` to `[1/T^n]` (v1.8 label was inaccurate; numeric value unchanged if `Di` was calibrated consistently); parameter `econRate` → `Q_econ`
`PowerLawExponentialDeclineTime(Qi_intercept, Di_intercept, D_inf, n, econRate)`	`PO.DCA.PLE.Time(Qi0, Di0, Dinf, n, Q_econ)`	renamed — parameters shortened; dimension of `Di0` refined from `[1/T]` to `[1/T^n]` (v1.8 label was inaccurate; numeric value unchanged if `Di` was calibrated consistently); parameter `econRate` → `Q_econ`
`PowerLawExponentialDeclineFitParameters(timeValues, rateValues)`	`PO.DCA.PLE.Fit(times, rates)`	renamed
`PowerLawExponentialDeclineWeightedFitParameters(timeValues, rateValues, weightsValues)`	`PO.DCA.PLE.WFit(times, rates, weights)`	renamed

Stretched Exponential (SEDM)

Old (v1.8)	New (v2.0)	Migration notes
`StretchedExponentialDeclineRate(Qi, tau, n, time)`	`PO.DCA.SEDM.Rate(Qi, tau, n, time)`	renamed
`StretchedExponentialDeclineCumulative(Qi, tau, n, time)`	`PO.DCA.SEDM.Prod(Qi, tau, n, time)`	renamed
`StretchedExponentialDeclineEUR(Qi, tau, n, econRate)`	`PO.DCA.SEDM.EUR(Qi, tau, n, Q_econ)`	renamed — parameter `econRate` → `Q_econ`
`StretchedExponentialDeclineTime(Qi, tau, n, econRate)`	`PO.DCA.SEDM.Time(Qi, tau, n, Q_econ)`	renamed — parameter `econRate` → `Q_econ`
`StretchedExponentialDeclineFitParameters(timeValues, rateValues)`	`PO.DCA.SEDM.Fit(times, rates)`	renamed
`StretchedExponentialDeclineWeightedFitParameters(timeValues, rateValues, weightsValues)`	`PO.DCA.SEDM.WFit(times, rates, weights)`	renamed

SSE / Error statistics (moved to `PO.Stats`)

Old (v1.8)	New (v2.0)	Migration notes
`ComputeSse(observedValues, predictedValues)`	`PO.Stats.SSE(observed, predicted)`	renamed
`ComputeLogSse(observedValues, predictedValues)`	`PO.Stats.LogSSE(observed, predicted)`	renamed
`ComputeWeightedSse(observedValues, predictedValues, weightsValues)`	`PO.Stats.WSSE(observed, predicted, weights)`	renamed
`ComputeWeightedLogSse(observedValues, predictedValues, weightsValues)`	`PO.Stats.WLogSSE(observed, predicted, weights)`	renamed

Field Profile (now in PO.FPP module)

Old (v1.8)	New (v2.0)	Migration notes
`BasicFieldProfile(time_buildup, time_plateau, Q_plateau, Di, time)`	`PO.FPP.Field.Rate(t_buildup, t_plateau, Q_plateau, Di, b, t)`	renamed — added parameter `b` (Arps b-factor; pass `b=0` for exponential tail)
`CombinedFieldProfile(timeSeries, profile, schedule, time)`	`PO.FPP.Sched.Rate(timeSeries, profile, schedule, t)`	renamed

PipeFlow

v1.8 PipeFlow is split into two v2.0 modules: PO.VFP (vertical/wellbore flow with inclination) for multiphase and single-phase-with-angle cases, and PO.SF.PL (surface pipeline) for horizontal-only liquid/gas pipelines. The v2.0 multiphase .Pin/.Pout correlations take a normalized parameter order: (Ql, Qg, P_boundary, T_degF, Rho_l, Ul, SG_gas, IFT_gl, pipe_ID, pipe_length, pipe_roughness[, pipe_angle]) — this differs from v1.8 which interleaved pressure/temperature near the end. Multiphase .dPdL (pressure gradient) adds PVT-property inputs Bl, Rho_g, Ug, Bg, Rs that were previously computed internally.

Single-phase liquid (horizontal) — moved to `PO.VFP.Liq` / `PO.SF.PL.Liq`

Old (v1.8)	New (v2.0)	Migration notes
`FrictionPressureDropLiquid(Ql, Ul, Rho_l, pipeID, pipeRoughness, pipeLength)`	`PO.VFP.Liq.dPfrc(Ql, Rho_l, Ul, pipe_ID, pipe_length, pipe_roughness)`	renamed — parameter order changed: `Ul, Rho_l` → `Rho_l, Ul`; `pipeLength, pipeRoughness` reordered
`PotentialEnergyPressureDropLiquid(Rho_l, pipeLength, pipeAngle)`	`PO.VFP.Liq.dPgrv(Rho_l, pipe_length, pipe_angle)`	renamed
`ReynoldsNumberLiquid(Ql, Rho_l, pipeID, Ul)`	`PO.VFP.Liq.Re(Ql, Rho_l, pipe_ID, Ul)`	renamed
`InletPipePressureLiquid(P_out, Ql, Ul, Rho_l, pipeID, pipeRoughness, pipeLength, pipeAngle)`	`PO.VFP.Liq.Pin(Ql, P_out, Rho_l, Ul, pipe_ID, pipe_length, pipe_roughness, pipe_angle)`	renamed — parameter order changed: `Ql` moved first; `Ul, Rho_l` swapped; `pipeRoughness, pipeLength` reordered
`OutletPipePressureLiquid(P_in, Ql, Ul, Rho_l, pipeID, pipeRoughness, pipeLength, pipeAngle)`	`PO.VFP.Liq.Pout(Ql, P_in, Rho_l, Ul, pipe_ID, pipe_length, pipe_roughness, pipe_angle)`	renamed — parameter order changed (same as `InletPipePressureLiquid`)

Single-phase gas (with angle) — moved to `PO.VFP.Gas`

Old (v1.8)	New (v2.0)	Migration notes
`ReynoldsNumberGas(Qg, SGgas, pipeID, Ug)`	`PO.VFP.Gas.Re(Qg, SG_gas, pipe_ID, Ug)`	renamed — unit `Qg [mscf/d] → [mmscf/D]` (1000× flip — divide old values by 1000)
`InletPipePressureGas(Qg, P_out, pipeLength, pipeID, pipeAngle, pipeRoughness, zFactor, T, SGgas, Ug)`	`PO.VFP.Gas.Pin(Qg, P_out, T_degF, SG_gas, Ug, Z, pipe_ID, pipe_length, pipe_roughness, pipe_angle)`	renamed — parameter order changed; unit `Qg [mscf/d] → [mmscf/D]` (1000× flip — divide old values by 1000)
`OutletPipePressureGas(Qg, P_in, pipeLength, pipeID, pipeAngle, pipeRoughness, zFactor, T, SGgas, Ug)`	`PO.VFP.Gas.Pout(Qg, P_in, T_degF, SG_gas, Ug, Z, pipe_ID, pipe_length, pipe_roughness, pipe_angle)`	renamed — parameter order changed (same as `.Pin`); unit `Qg [mscf/d] → [mmscf/D]` (1000× flip — divide old values by 1000)

Multiphase Beggs-Brill

Old (v1.8)	New (v2.0)	Migration notes
`InletPressureBeggsBrill(Ql, Rho_l, Ul, Qg, SGgas, IFTgl, pipeID, pipeLength, pipeRoughness, pipeAngle, P_out, T)`	`PO.VFP.BeggsBrill.Pin(Ql, Qg, P_out, T_degF, Rho_l, Ul, SG_gas, IFT_gl, pipe_ID, pipe_length, pipe_roughness, pipe_angle)`	renamed — parameter order changed (normalized to `Ql, Qg, P, T, Rho_l, Ul, SG, IFT, geometry`)
`OutletPressureBeggsBrill(Ql, Rho_l, Ul, Qg, SGgas, IFTgl, pipeID, pipeLength, pipeRoughness, pipeAngle, P_in, T)`	`PO.VFP.BeggsBrill.Pout(Ql, Qg, P_in, T_degF, Rho_l, Ul, SG_gas, IFT_gl, pipe_ID, pipe_length, pipe_roughness, pipe_angle)`	renamed — parameter order changed (as above)
`PressureGradientBeggsBrill(Ql, Rho_l, Ul, Qg, Ug, SGgas, zFactor, IFTgl, pipeID, pipeRoughness, pipeAngle, P, T)`	`PO.VFP.BeggsBrill.dPdL(Ql, Qg, P, Rho_l, Ul, Bl, Rho_g, Ug, Bg, IFT_gl, Rs, pipe_ID, pipe_roughness, pipe_angle)`	renamed — parameter order changed; added parameters `Bl, Rho_g, Bg, Rs`; removed `SGgas, zFactor, T` (gas properties now passed explicitly)

Multiphase Gray

Old (v1.8)	New (v2.0)	Migration notes
`InletPressureGray(Ql, Rho_l, Ul, Qg, SGgas, IFTgl, pipeID, pipeLength, pipeRoughness, pipeAngle, P_out, T)`	`PO.VFP.Gray.Pin(Ql, Qg, P_out, T_degF, Rho_l, Ul, SG_gas, IFT_gl, pipe_ID, pipe_length, pipe_roughness, pipe_angle)`	renamed — parameter order changed
`OutletPressureGray(Ql, Rho_l, Ul, Qg, SGgas, IFTgl, pipeID, pipeLength, pipeRoughness, pipeAngle, P_in, T)`	`PO.VFP.Gray.Pout(Ql, Qg, P_in, T_degF, Rho_l, Ul, SG_gas, IFT_gl, pipe_ID, pipe_length, pipe_roughness, pipe_angle)`	renamed — parameter order changed
`PressureGradientGray(Ql, Rho_l, Ul, Qg, Ug, SGgas, zFactor, IFTgl, pipeID, pipeRoughness, pipeAngle, P, T)`	`PO.VFP.Gray.dPdL(Ql, Qg, P, Rho_l, Ul, Bl, Rho_g, Ug, Bg, IFT_gl, Rs, pipe_ID, pipe_roughness, pipe_angle)`	renamed — parameter order changed; added `Bl, Rho_g, Bg, Rs`; removed `SGgas, zFactor, T`

Multiphase Hagedorn-Brown

Old (v1.8)	New (v2.0)	Migration notes
`InletPressureHarBrown(Ql, Rho_l, Ul, Qg, SGgas, IFTgl, pipeID, pipeLength, pipeRoughness, P_out, T)`	`PO.VFP.HagedornBrown.Pin(Ql, Qg, P_out, T_degF, Rho_l, Ul, SG_gas, IFT_gl, pipe_ID, pipe_length, pipe_roughness)`	renamed — parameter order changed
`OutletPressureHarBrown(Ql, Rho_l, Ul, Qg, SGgas, IFTgl, pipeID, pipeLength, pipeRoughness, P_in, T)`	`PO.VFP.HagedornBrown.Pout(Ql, Qg, P_in, T_degF, Rho_l, Ul, SG_gas, IFT_gl, pipe_ID, pipe_length, pipe_roughness)`	renamed — parameter order changed
`PressureGradientHarBrown(Ql, Rho_l, Ul, Qg, Ug, SGgas, zFactor, IFTgl, pipeID, pipeRoughness, P, T)`	`PO.VFP.HagedornBrown.dPdL(Ql, Qg, P, Rho_l, Ul, Bl, Rho_g, Ug, Bg, IFT_gl, Rs, pipe_ID, pipe_roughness)`	renamed — parameter order changed; added `Bl, Rho_g, Bg, Rs`; removed `SGgas, zFactor, T`

PTA

v1.8 PTA prefix Pdw* / Pw* / pta* reorganized into PO.PTA.PD.VW.* (dimensionless wellbore pressure for vertical wells), PO.PTA.Pw.VW.* (dimensional wellbore pressure), and PO.PTA.ToDim.* (converters from dimensional to dimensionless). Boundary suffixes renamed: LCPB → LinConP, LSFB → LinSealF, PCPB → PerpConP, PMB → PerpMix, PSFB → PerpSealF. The Pw* family also changes the prodData parameter unit from [STB/D] to [bbl/D] (numerically identical for oil at standard conditions — relabel only) and renames the permeability parameter from lowercase k to uppercase K.

Old (v1.8)	New (v2.0)	Migration notes
`PdLSSIHR(td, rd)`	`PO.PTA.PD.LSS(tD, rD)`	renamed
`PdwVWIHR(td, cd, skinFactor)`	`PO.PTA.PD.VW(tD, CD, S)`	renamed
`PdwVWIHRLCPB(td, cd, skinFactor, Ld)`	`PO.PTA.PD.VW.LinConP(tD, CD, S, LD)`	renamed
`PdwVWIHRLSFB(td, cd, skinFactor, Ld)`	`PO.PTA.PD.VW.LinSealF(tD, CD, S, LD)`	renamed
`PdwVWIHRPCPB(td, cd, skinFactor, Ld1, Ld2)`	`PO.PTA.PD.VW.PerpConP(tD, CD, S, LD1, LD2)`	renamed
`PdwVWIHRPMB(td, cd, skinFactor, Ld1, Ld2)`	`PO.PTA.PD.VW.PerpMix(tD, CD, S, LD1, LD2)`	renamed
`PdwVWIHRPSFB(td, cd, skinFactor, Ld1, Ld2)`	`PO.PTA.PD.VW.PerpSealF(tD, CD, S, LD1, LD2)`	renamed
`PwVWIHR(time, prodData, B, Ul, C, Rw, S, Ct, porosity, h, k)`	`PO.PTA.Pw.VW(time, prod_data, B, Ul, C, Rw, S, Ct, porosity, h, K)`	renamed — parameter `k` → `K`; unit `prodData [STB/D] → [bbl/D]`
`PwVWIHRLCPB(time, prodData, B, Ul, C, Rw, S, Ct, porosity, h, k, L)`	`PO.PTA.Pw.VW.LinConP(time, prod_data, B, Ul, C, Rw, S, Ct, porosity, h, K, L)`	renamed — parameter `k` → `K`; unit `prodData [STB/D] → [bbl/D]`
`PwVWIHRLSFB(time, prodData, B, Ul, C, Rw, S, Ct, porosity, h, k, L)`	`PO.PTA.Pw.VW.LinSealF(time, prod_data, B, Ul, C, Rw, S, Ct, porosity, h, K, L)`	renamed — parameter `k` → `K`; unit `prodData [STB/D] → [bbl/D]`
`PwVWIHRPCPB(time, prodData, B, Ul, C, Rw, S, Ct, porosity, h, k, L1, L2)`	`PO.PTA.Pw.VW.PerpConP(time, prod_data, B, Ul, C, Rw, S, Ct, porosity, h, K, L1, L2)`	renamed — parameter `k` → `K`; unit `prodData [STB/D] → [bbl/D]`
`PwVWIHRPMB(time, prodData, B, Ul, C, Rw, S, Ct, porosity, h, k, L1, L2)`	`PO.PTA.Pw.VW.PerpMix(time, prod_data, B, Ul, C, Rw, S, Ct, porosity, h, K, L1, L2)`	renamed — parameter `k` → `K`; unit `prodData [STB/D] → [bbl/D]`
`PwVWIHRPSFB(time, prodData, B, Ul, C, Rw, S, Ct, porosity, h, k, L1, L2)`	`PO.PTA.Pw.VW.PerpSealF(time, prod_data, B, Ul, C, Rw, S, Ct, porosity, h, K, L1, L2)`	renamed — parameter `k` → `K`; unit `prodData [STB/D] → [bbl/D]`
`ptaCd(C, poro, ct, h, rw)`	`PO.PTA.ToDim.CD(C, porosity, Ct, h, Rw)`	renamed
`ptaLd(l, rw)`	`PO.PTA.ToDim.LD(L, Rw)`	renamed
`ptaPd(P, Pi, q, k, h, B, mu)`	`PO.PTA.ToDim.PD(P, Pi, q, K, h, B, Ul)`	renamed — parameter `mu` → `Ul`; parameter `k` → `K`; unit `q [STB/D] → [bbl/D]`
`ptaRwd(r, rw)`	`PO.PTA.ToDim.rD(r, Rw)`	renamed
`ptaTd(t, k, poro, mu, ct, rw)`	`PO.PTA.ToDim.tD(t, K, porosity, Ul, Ct, Rw)`	renamed — parameter `mu` → `Ul`; parameter `k` → `K`

PVT

PVT reorganizes by quantity → correlation: e.g., every bubble-point correlation becomes PO.PVT.Pb.By<Author>. Oil viscosity splits cleanly into .Dead, .Sat, .UnSat families. Temperature parameters now explicitly suffix _degF or _degR to prevent unit confusion. SGoilAPI → API, SGgas → SG_gas, Rso/Rsob → Rs/Rsb, zFactor → Z. New correlations (Beal, Glaso dead oil, ChewConnally, Kouzel) are new in v2.0. v2.0 relabels [psia] → [psi] across most PVT rows (numerically identical — both mean absolute pressure); [degR], [degF], [cP], [rcf/scf], [bbl/STB], [scf/STB] are unchanged. Individual rows do NOT flag the psia → psi relabel — it applies universally. Only the one real gauge-vs-absolute change (RsoDindorukChristman2001: [psig] → [psi]) is flagged.

Gas properties

Old (v1.8)	New (v2.0)	Migration notes
`Bg(P, T, zFactor)`	`PO.PVT.Bg.ByDefinition(P, T_degR, Z)`	renamed
`Cg(P, T, SGgas)`	`PO.PVT.Cg.ByDefinition(P, T_degR, SG_gas)`	renamed
`GasDensity(P, T, SGgas, zFactor)`	`PO.PVT.Rho.Gas.ByDefinition(P, T_degR, SG_gas, Z)`	renamed
`UgLGE(zFactor, SGgas, P, T)`	`PO.PVT.Ug.ByLGE(Z, SG_gas, P, T_degR)`	renamed
`PpcStanding(SGgas)`	`PO.PVT.Ppc.ByStanding(SG_gas)`	renamed
`PpcSutton(SGgas)`	`PO.PVT.Ppc.BySutton(SG_gas)`	renamed
`TpcStanding(SGgas)`	`PO.PVT.Tpc.ByStanding(SG_gas)`	renamed
`TpcSutton(SGgas)`	`PO.PVT.Tpc.BySutton(SG_gas)`	renamed
`ZfactorBrillBeggs(Ppr, Tpr)`	`PO.PVT.Z.ByBrillBeggs(Ppr, Tpr)`	renamed
`ZfactorDAK(Ppr, Tpr)`	`PO.PVT.Z.ByDAK(Ppr, Tpr)`	renamed

Oil — bubble-point pressure

Old (v1.8)	New (v2.0)	Migration notes
`PboAlMarhoun(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Pb.ByAlMarhoun(SG_gas, API, Rs, T_degF)`	renamed
`PboDindorukChristman(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Pb.ByDindorukChristman(SG_gas, API, Rs, T_degF)`	renamed
`PboDoklaOsman(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Pb.ByDoklaOsman(SG_gas, API, Rs, T_degF)`	renamed
`PboGlaso(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Pb.ByGlaso(SG_gas, API, Rs, T_degF)`	renamed
`PboPetroskyFarshad(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Pb.ByPetroskyFarshad(SG_gas, API, Rs, T_degF)`	renamed
`PboStanding(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Pb.ByStanding(SG_gas, API, Rs, T_degF)`	renamed
`PboVasquezBeggs(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Pb.ByVasquezBeggs(SG_gas, API, Rs, T_degF)`	renamed

Oil — formation volume factor (Bo)

Old (v1.8)	New (v2.0)	Migration notes
`BoSatAlMarhoun1988(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Bo.Sat.ByAlMarhoun(SG_gas, API, Rs, T_degF)`	renamed
`BoSatDindorukChristman2001(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Bo.Sat.ByDindorukChristman(SG_gas, API, Rs, T_degF)`	renamed
`BoSatGlaso1980(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Bo.Sat.ByGlaso(SG_gas, API, Rs, T_degF)`	renamed
`BoSatPetrosky1990(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Bo.Sat.ByPetrosky(SG_gas, API, Rs, T_degF)`	renamed
`BoSatStanding1947(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Bo.Sat.ByStanding(SG_gas, API, Rs, T_degF)`	renamed
`BoSatVasquezBeggs1980(SGgas, SGoilAPI, Rso, T)`	`PO.PVT.Bo.Sat.ByVasquezBeggs(SG_gas, API, Rs, T_degF)`	renamed
`BoUSat(Bob, Co, Pb, P)`	`PO.PVT.Bo.UnSat.ByDefinition(Bob, Co, Pb, P)`	renamed

Oil — solution gas-oil ratio (Rs)

Old (v1.8)	New (v2.0)	Migration notes
`RsoAlMarhoun1988(SGgas, SGoilAPI, P, T)`	`PO.PVT.Rs.ByAlMarhoun(SG_gas, API, P, T_degF)`	renamed
`RsoDindorukChristman2001(SGgas, SGoilAPI, P, T)`	`PO.PVT.Rs.ByDindorukChristman(SG_gas, API, P, T_degF)`	renamed — unit `P [psig] → [psi]` (real change: v1.8 took gauge pressure, v2.0 takes absolute — add ~14.7 psi)
`RsoGlaso1980(SGgas, SGoilAPI, P, T)`	`PO.PVT.Rs.ByGlaso(SG_gas, API, P, T_degF)`	renamed
`RsoPetroskyFarshad1993(SGgas, SGoilAPI, P, T)`	`PO.PVT.Rs.ByPetroskyFarshad(SG_gas, API, P, T_degF)`	renamed
`RsoStanding1981(SGgas, SGoilAPI, P, T)`	`PO.PVT.Rs.ByStanding(SG_gas, API, P, T_degF)`	renamed
`RsoVasquezBeggs1980(SGgas, SGoilAPI, P, T)`	`PO.PVT.Rs.ByVasquezBeggs(SG_gas, API, P, T_degF)`	renamed

Oil — compressibility, viscosity, interfacial tension

Old (v1.8)	New (v2.0)	Migration notes
`CoSatVillenaLanzi1985(P, Pb, T, Rsob, SGoilAPI)`	`PO.PVT.Co.Sat.ByVillenaLanzi(P, Pb, T_degF, Rsb, API)`	renamed
`CoUSatVasquezBeggs1980(Rsob, SGgas, SGoilAPI, T, P)`	`PO.PVT.Co.UnSat.ByVasquezBeggs(Rsb, SG_gas, API, T_degF, P)`	renamed
`UodEgbogah1983(SGoilAPI, T)`	`PO.PVT.Uo.Dead.ByEgbogah(API, T_degF)`	renamed
`UoSatBeggsRobinson1975(Rso, Uod)`	`PO.PVT.Uo.Sat.ByBeggsRobinson(Rs, Uo_dead)`	renamed
`UoUSatVasquezBeggs1980(P, Pb, Uob)`	`PO.PVT.Uo.UnSat.ByVasquezBeggs(P, Pb, Uob)`	renamed
`IFTgoAbdulMajeed(SGoilAPI, T, Rso)`	`PO.PVT.IFT.GasOil.ByAbdulMajeed(API, T_degF, Rs)`	renamed — result unit `[dymes/cm]` typo fixed to `[dynes/cm]`
`IFTgoBakerSwerdloff(SGoilAPI, T, P)`	`PO.PVT.IFT.GasOil.ByBakerSwerdloff(API, T_degF, P)`	renamed — result unit `[dymes/cm]` typo fixed to `[dynes/cm]`

Water

Old (v1.8)	New (v2.0)	Migration notes
`BwMcCain(P, T)`	`PO.PVT.Bw.ByMcCain(P, T_degF)`	renamed
`CwSatMcCain(P, T, Cs)`	`PO.PVT.Cw.Sat.ByMcCain(P, T_degF, salinity_gl)`	renamed — parameter `Cs` → `salinity_gl` (units `g NaCl/l` unchanged)
`CwUSatOsif(P, T, Cs)`	`PO.PVT.Cw.UnSat.ByOsif(P, T_degF, salinity_gl)`	renamed — parameter `Cs` → `salinity_gl` (units `g NaCl/l` unchanged)
`RswpMcCain(P, T)`	`PO.PVT.Rsw.Pure.ByMcCain(P, T_degF)`	renamed
`RswMcCain(Rswp, salinity, T)`	`PO.PVT.Rsw.ByMcCain(Rsw_pure, salinity_pct, T_degF)`	renamed — salinity units `% by weight` unchanged
`Uw1McCain(T, salinity)`	`PO.PVT.Uw.1Atm.ByMcCain(T_degF, salinity_pct)`	renamed — salinity units `% by weight` unchanged
`UwMcCain(P, Uw1)`	`PO.PVT.Uw.ByMcCain(P, Uw_1atm)`	renamed

SCAL

SCAL modules split by system (gas-oil, gas-water, gas-condensate, two-phase oil-water) and by wettability (SWW / WW / IW / OW). The v1.8 Krow*/Krw* prefix is replaced with a hierarchical PO.SCAL.<Model>.<Rock>.<Wettability>.Krow / .Krw. Parameter lists and units are unchanged in every case — the only parameter rename is lowercase k → uppercase K for permeability. New v2.0 additions (not migrated from v1.8): Stone I/II three-phase, Brooks-Corey, Van Genuchten, Leverett J-function, and Honarpour.*.GasOil.* which add krgAtSorg. v1.8's pore-volume compressibility CfNewman[L|S] becomes PO.SCAL.Cf.[Lime|Sand].ByNewman.

Rock compressibility

Old (v1.8)	New (v2.0)	Migration notes
`CfNewmanL(porosity)`	`PO.SCAL.Cf.Lime.ByNewman(porosity)`	renamed
`CfNewmanS(porosity)`	`PO.SCAL.Cf.Sand.ByNewman(porosity)`	renamed

Corey / LET two-phase

Old (v1.8)	New (v2.0)	Migration notes
`KrowCorey(Sw, Swi, Sorw, KrowSwi, No)`	`PO.SCAL.Corey.Krow(Sw, Swi, Sorw, Krow_Swi, No)`	renamed
`KrwCorey(Sw, Swi, Sorw, KrwSorw, Nw)`	`PO.SCAL.Corey.Krw(Sw, Swi, Sorw, Krw_Sorw, Nw)`	renamed
`KrowLET(Sw, Swi, Sorw, KrowSwi, Lo, Eo, To)`	`PO.SCAL.LET.Krow(Sw, Swi, Sorw, Krow_Swi, Lo, Eo, To)`	renamed
`KrwLET(Sw, Swi, Sorw, KrwSorw, Lw, Ew, Tw)`	`PO.SCAL.LET.Krw(Sw, Swi, Sorw, Krw_Sorw, Lw, Ew, Tw)`	renamed

Honarpour oil-water (sandstone / carbonate × WW / IW)

Old (v1.8)	New (v2.0)	Migration notes
`KrowHonarpourSandWaterWet(Sw, Swi, Sorw, porosity)`	`PO.SCAL.Honarpour.Sand.WW.Krow(Sw, Swi, Sorw, porosity)`	renamed
`KrwHonarpourSandWaterWet(Sw, Swi, Sorw, porosity)`	`PO.SCAL.Honarpour.Sand.WW.Krw(Sw, Swi, Sorw, porosity)`	renamed
`KrowHonarpourSandInterWet(Sw, Swi, Sorw, porosity)`	`PO.SCAL.Honarpour.Sand.IW.Krow(Sw, Swi, Sorw, porosity)`	renamed
`KrwHonarpourSandInterWet(Sw, Swi, Sorw, porosity)`	`PO.SCAL.Honarpour.Sand.IW.Krw(Sw, Swi, Sorw, porosity)`	renamed
`KrowHonarpourCarbWaterWet(Sw, Swi, Sorw, porosity, k)`	`PO.SCAL.Honarpour.Carb.WW.Krow(Sw, Swi, Sorw, porosity, K)`	renamed — parameter `k` → `K`
`KrwHonarpourCarbWaterWet(Sw, Swi, Sorw, porosity, k)`	`PO.SCAL.Honarpour.Carb.WW.Krw(Sw, Swi, Sorw, porosity, K)`	renamed — parameter `k` → `K`
`KrowHonarpourCarbInterWet(Sw, Swi, Sorw)`	`PO.SCAL.Honarpour.Carb.IW.Krow(Sw, Swi, Sorw)`	renamed
`KrwHonarpourCarbInterWet(Sw, Swi, Sorw)`	`PO.SCAL.Honarpour.Carb.IW.Krw(Sw, Swi, Sorw)`	renamed

Ibrahim-Koederitz oil-water (sandstone / carbonate × SWW / WW / IW / OW)

Old (v1.8)	New (v2.0)	Migration notes
`KrowIKSandStrongWaterWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Sand.SWW.Krow(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrwIKSandStrongWaterWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Sand.SWW.Krw(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrowIKSandWaterWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Sand.WW.Krow(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrwIKSandWaterWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Sand.WW.Krw(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrowIKSandInterWet(Sw, Swi, Sorw)`	`PO.SCAL.IK.Sand.IW.Krow(Sw, Swi, Sorw)`	renamed
`KrwIKSandInterWet(Sw, Swi, Sorw)`	`PO.SCAL.IK.Sand.IW.Krw(Sw, Swi, Sorw)`	renamed
`KrowIKSandOilWet(Sw, Swi, Sorw)`	`PO.SCAL.IK.Sand.OW.Krow(Sw, Swi, Sorw)`	renamed
`KrwIKSandOilWet(Sw, Swi, Sorw)`	`PO.SCAL.IK.Sand.OW.Krw(Sw, Swi, Sorw)`	renamed
`KrowIKCarbStrongWaterWet(Sw, Swi, Sorw, Swc)`	`PO.SCAL.IK.Carb.SWW.Krow(Sw, Swi, Sorw, Swc)`	renamed
`KrwIKCarbStrongWaterWet(Sw, Swi, Sorw, Swc)`	`PO.SCAL.IK.Carb.SWW.Krw(Sw, Swi, Sorw, Swc)`	renamed
`KrowIKCarbWaterWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Carb.WW.Krow(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrwIKCarbWaterWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Carb.WW.Krw(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrowIKCarbInterWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Carb.IW.Krow(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrwIKCarbInterWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Carb.IW.Krw(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrowIKCarbOilWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Carb.OW.Krow(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`
`KrwIKCarbOilWet(Sw, Swi, Sorw, Swc, porosity, k)`	`PO.SCAL.IK.Carb.OW.Krw(Sw, Swi, Sorw, Swc, porosity, K)`	renamed — parameter `k` → `K`

Ibrahim-Koederitz gas-oil / gas-water / gas-condensate

Old (v1.8)	New (v2.0)	Migration notes
`KrgIKGasOilSand(Sg, Sgc, Sorg, Swc, Slc, porosity)`	`PO.SCAL.IK.Sand.GasOil.Krg(Sg, Sgc, Sorg, Swc, Slc, porosity)`	renamed
`KrogIKGasOilSand(Sg, Sgc, Sorg, Swc, Slc, porosity)`	`PO.SCAL.IK.Sand.GasOil.Krog(Sg, Sgc, Sorg, Swc, Slc, porosity)`	renamed
`KrgIKGasOilCarb(Sg, Sgc, Swc, Slc, porosity, k)`	`PO.SCAL.IK.Carb.GasOil.Krg(Sg, Sgc, Swc, Slc, porosity, K)`	renamed — parameter `k` → `K`
`KrogIKGasOilCarb(Sg, Sgc, Swc, Slc, porosity, k)`	`PO.SCAL.IK.Carb.GasOil.Krog(Sg, Sgc, Swc, Slc, porosity, K)`	renamed — parameter `k` → `K`
`KrgwIKGasWater(Sg, Sgc, Swc, Slc, porosity, k)`	`PO.SCAL.IK.GasWat.Krgw(Sg, Sgc, Swc, Slc, porosity, K)`	renamed — parameter `k` → `K`
`KrwIKGasWater(Sg, Sgc, Swc, Slc, porosity, k)`	`PO.SCAL.IK.GasWat.Krw(Sg, Sgc, Swc, Slc, porosity, K)`	renamed — parameter `k` → `K`
`KrgIKGasCond(Sg, Sgc, Slc)`	`PO.SCAL.IK.GasCond.Krg(Sg, Sgc, Slc)`	renamed
`KrcgIKGasCond(Sg, Sgc, Slc)`	`PO.SCAL.IK.GasCond.Krcg(Sg, Sgc, Slc)`	renamed

Utilities

Spline and interpolation functions moved into PO.Spline.* and PO.Math.*. Parameter names follow snake_case convention (xValues → x_values) but units and semantics are unchanged. API2SG / SG2API moved into the PVT module. UnitConverter keeps its top-level flat identifier as PO.UnitConverter.

Old (v1.8)	New (v2.0)	Migration notes
`API2SG(SGoilAPI)`	`PO.PVT.SG.Oil.FromAPI(API)`	renamed — moved to PVT module
`SG2API(SGoil)`	`PO.PVT.API.FromSGoil(SG_oil)`	renamed — moved to PVT module
`UnitConverter(Value, UnitFrom, UnitTo)`	`PO.UnitConverter(value, unit_from, unit_to)`	renamed
`ExpIntegralEi(x)`	`PO.Math.Ei(x)`	renamed
`DataDifferentiate(xValues, yValues, t, l)`	`PO.Math.DataDiff(x_values, y_values, t, l)`	renamed
`CubicSplineInterpolate(xValues, yValues, t)`	`PO.Spline.Cubic.Interp(x_values, y_values, t)`	renamed
`CubicSplineDifferentiate(xValues, yValues, t)`	`PO.Spline.Cubic.Diff(x_values, y_values, t)`	renamed
`CubicSplineIntegrate(xValues, yValues, t)`	`PO.Spline.Cubic.Integ(x_values, y_values, t)`	renamed
`CubicSplineIntegrateT1T2(xValues, yValues, t1, t2)`	`PO.Spline.Cubic.IntegT1T2(x_values, y_values, t1, t2)`	renamed
`CubicSplinesIntersection(xValues1, yValues1, xValues2, yValues2)`	`PO.Spline.Cubic.Intersect(x_values_1, y_values_1, x_values_2, y_values_2)`	renamed
`LinearSplineInterpolate(xValues, yValues, t)`	`PO.Spline.Linear.Interp(x_values, y_values, t)`	renamed
`LinearSplineDifferentiate(xValues, yValues, t)`	`PO.Spline.Linear.Diff(x_values, y_values, t)`	renamed
`LinearSplineIntegrate(xValues, yValues, t)`	`PO.Spline.Linear.Integ(x_values, y_values, t)`	renamed
`LinearSplineIntegrateT1T2(xValues, yValues, t1, t2)`	`PO.Spline.Linear.IntegT1T2(x_values, y_values, t1, t2)`	renamed
`LinearSplinesIntersection(xValues1, yValues1, xValues2, yValues2)`	`PO.Spline.Linear.Intersect(x_values_1, y_values_1, x_values_2, y_values_2)`	renamed
`ProximalInterpolate(xValues, yValues, t)`	`PO.Spline.Proximal.Interp(x_values, y_values, t)`	renamed
`StepInterpolate(xValues, yValues, t)`	`PO.Spline.Step.Interp(x_values, y_values, t)`	renamed

WellFlow

v1.8 WellFlow maps to v2.0 PO.IPR (Inflow Performance Relationships). Vertical vs horizontal well split into PO.IPR.VW.* and PO.IPR.HW.*; PSS / SS / TF flow regimes exposed as explicit sub-namespaces. Gas well functions grouped under PO.IPR.GW.*. ProdIndex* → PO.IPR.*.PI, FlowRate* → PO.IPR.*.Rate. Many vertical-well rows shift result unit wording from [STB/d] / [STB/(d.psi)] to [bbl/D] / [bbl/(D.psi)] — numerically identical for oil at standard conditions. Horizontal-well PI rows (ByBorisov, ByBabuOdeh, ByGRJ, ByJoshi, ByRenardDupuy) keep [STB/(d.psi)] unchanged.

Utility functions

Old (v1.8)	New (v2.0)	Migration notes
`DrainageRadius(A)`	`PO.IPR.Re(A)`	renamed
`EffectiveWellboreRadius(Rw, S)`	`PO.IPR.Rwa(Rw, S)`	renamed
`EquivalentSkinFactor(Xf, W, K_fracture, K, Rw)`	`PO.FRAC.Well.SkinEq(Xf, W, Kf, K, Rw)`	renamed — parameter `K_fracture` → `Kf`; moved to new FRAC module

Vertical well — productivity index and flow rate

Old (v1.8)	New (v2.0)	Migration notes
`ProdIndexPSS(K, h, Bl, Ul, Re, Rw, S)`	`PO.IPR.VW.PSS.PI(K, h, Bl, Ul, Re, Rw, S)`	renamed — result unit `[STB/(d.psi)] → [bbl/(D.psi)]` (relabel only, numerically equivalent for oil at standard conditions)
`ProdIndexSS(K, h, Bl, Ul, Re, Rw, S)`	`PO.IPR.VW.SS.PI(K, h, Bl, Ul, Re, Rw, S)`	renamed — result unit `[STB/(d.psi)] → [bbl/(D.psi)]` (relabel only)
`ProdIndexTF(time, K, h, Bl, Ul, porosity, Ct, Rw, S)`	`PO.IPR.VW.TF.PI(time, K, h, Bl, Ul, porosity, Ct, Rw, S)`	renamed — result unit `[STB/(d.psi)] → [bbl/(D.psi)]` (relabel only)
`FlowRatePSS(J, P_average, Pwf)`	`PO.IPR.VW.PSS.Rate(J, P_average, Pwf)`	renamed — result unit `[STB/d] → [bbl/D]` (relabel only)
`FlowRateSS(J, Pe, Pwf)`	`PO.IPR.VW.SS.Rate(J, Pe, Pwf)`	renamed — result unit `[STB/d] → [bbl/D]` (relabel only)
`FlowRateTF(J, Pi, Pwf)`	`PO.IPR.VW.TF.Rate(J, Pi, Pwf)`	renamed — result unit `[STB/d] → [bbl/D]` (relabel only)
`FlowRatePSSVogel(J, P_average, Pwf, Pb)`	`PO.IPR.VW.PSS.Rate.ByVogel(J, P_average, Pwf, Pb)`	renamed — result unit `[STB/d] → [bbl/D]` (relabel only)
`FlowRateSSVogel(J, Pe, Pwf, Pb)`	`PO.IPR.VW.SS.Rate.ByVogel(J, Pe, Pwf, Pb)`	renamed — result unit `[STB/d] → [bbl/D]` (relabel only)
`FlowRateTFVogel(J, Pi, Pwf, Pb)`	`PO.IPR.VW.TF.Rate.ByVogel(J, Pi, Pwf, Pb)`	renamed — result unit `[STB/d] → [bbl/D]` (relabel only)
`TimeToPSS(Re, K, Ul, porosity, Ct)`	`PO.IPR.VW.PSS.Time(Re, K, Ul, porosity, Ct)`	renamed

Gas well

Old (v1.8)	New (v2.0)	Migration notes
`GasFlowRatePSS(K, h, P_average, Pwf, zFactor, Ug, Re, Rw, S, T)`	`PO.IPR.GW.PSS.Rate(K, h, P_average, Pwf, Z, Ug, Re, Rw, S, T_degR)`	renamed
`GasFlowRatePSSNonDarcy(K, h, P_average, Pwf, zFactor, Ug, Re, Rw, S, T, D)`	`PO.IPR.GW.PSS.Rate.NonDarcy(K, h, P_average, Pwf, Z, Ug, Re, Rw, S, T_degR, D)`	renamed
`NonDarcyCoefficient(Rw, h, h_perf, SGgas, Ug, K)`	`PO.IPR.GW.D(Rw, h, h_perf, SG_gas, Ug, K)`	renamed
`TimeToPSSGas(Re, Rw, porosity, K, Ct, Ug)`	`PO.IPR.GW.PSS.Time(Re, Rw, K, porosity, Ct, Ug)`	renamed — parameter order changed: `porosity, K` → `K, porosity`

Horizontal well — productivity index and drainage

Old (v1.8)	New (v2.0)	Migration notes
`DrainageAreaHorWell1(L, b)`	`PO.IPR.HW.DrainArea.Rect(L, b)`	renamed
`DrainageAreaHorWell2(L, b)`	`PO.IPR.HW.DrainArea.Ellipse(L, b)`	renamed
`ProdIndexHorWellBO(sizeX, sizeY, sizeZ, Kx, Ky, Kz, L, Rw, Bl, Ul, S, x1, y0, z0)`	`PO.IPR.HW.PSS.PI.ByBabuOdeh(size_x, size_y, size_z, Kx, Ky, Kz, L, Rw, Bl, Ul, S, x1, y0, z0)`	renamed
`ProdIndexHorWellBO2(sizeX, sizeY, sizeZ, Kx, Ky, Kz, L, Rw, Bl, Ul, S)`	`PO.IPR.HW.PSS.PI.ByBabuOdeh.Centered(size_x, size_y, size_z, Kx, Ky, Kz, L, Rw, Bl, Ul, S)`	renamed
`ProdIndexHorWellBorisov(L, Rw, Re, h, K, Bl, Ul)`	`PO.IPR.HW.SS.PI.ByBorisov(L, Rw, Re, h, K, Bl, Ul)`	renamed — regime re-declared as SS
`ProdIndexHorWellGRJ(L, Rw, Re, h, Kz, Kxy, Bl, Ul)`	`PO.IPR.HW.SS.PI.ByGRJ(L, Rw, Re, h, Kz, Kxy, Bl, Ul)`	renamed
`ProdIndexHorWellJoshi(L, Rw, Re, h, Kz, Kxy, Bl, Ul)`	`PO.IPR.HW.SS.PI.ByJoshi(L, Rw, Re, h, Kz, Kxy, Bl, Ul)`	renamed
`ProdIndexHorWellRD(L, Rw, Re, h, Kz, Kxy, Bl, Ul)`	`PO.IPR.HW.SS.PI.ByRenardDupuy(L, Rw, Re, h, Kz, Kxy, Bl, Ul)`	renamed

Unmapped / deprecated

All 213 v1.8 functions map to a v2.0 equivalent. None deprecated or removed. EquivalentSkinFactor moved across modules (WellFlow → PO.FRAC.Well.SkinEq) but semantics are identical.