NPHI–RHOB Crossplot · Petrophysical Analysis

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NPHI (p.u.)

RHOB (g/cm³)

Sample Name

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Columns: Name, NPHI, RHOB

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#	Name	NPHI	RHOB	φ%	Lithology
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Columns: Index · Name · NPHI · RHOB · Porosity (%) · Lithology · Fluid

Source: Schlumberger 2013 Por-11 · High-Fidelity v2
Fresh water: ρf=1.000 g/cm³, Cf=0 ppm · Catmull-Rom spline
Salt water: ρf=1.146 g/cm³ (200k ppm NaCl) · ΔNPHI=–φ×15 p.u.
Gas: ρf=0.200 g/cm³, HI_gas=0.35 · φN_gas=φN_fw×0.35
Dolomite: peak Δ=+3.0 p.u. at φ=20–25%, converges to Δ=+0.5 at φ=45%
Quartz: Δ grows from –2.0 p.u. at φ=0 to –7.5 p.u. at φ=45%

NPHI – RHOB Crossplot

Liquid-Filled Borehole · ρ_f=1.000 g/cm³, C_f=0 ppm · Schlumberger 2013 Por-11 · High-Fidelity v2

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ρ_b — Bulk Density (g/cm³)

φ_D — Density Porosity (%) [ρ_ma=2.71, ρ_f=1.00]

φ_N — Neutron Porosity Index (p.u.) — Apparent Limestone Matrix