Calculate Water Saturation Sw (Schlumberger, 1975)

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Water Saturation (Sw)- Schlumberger (1975)

Schlumberger (1975) also proposed an equation to calculate water saturation, and the parameters included in that expression are very similar to the ones used in Ferlt's equation (1975), but adding a different parameter: a shale/clay resistivity value. The similar parameters are shale volume, porosity, water resistivity, and true formation resistivity. The equation is the following:

Where:
• Sw= water saturation of the uninvaded zone
• Rt= true formation resistivity (i.e., deep induction or deep laterolog corrected for invasion)
• Rw= resistivity of formation water at formation temperature
• ɸ = porosity
• Vshale= shale volume
• Rshale= shale/clay resistivity value in a formation

Calculate Water Saturation (Sw) - Schlumberger (1975)
Vsh: Decimal		Rsh: ohm-m
ɸ: Decimal		Rw: ohm-m
Rt: ohm-m

Made by Henry Herrera

Calculate Density Porosity - Shale Corrected - (Schlumberger, 1975)

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Density Log Porosity - Shale Corrected - Schlumberger (1975)

Schlumberger (1975) also proposed a shale correction for porosity values derived from density logs. In this case, the equation includes density value of a nearby shale at the depth of the study area, and shale volume. The expression is the following:

Where:
• ɸDe= density log porosity - shale corrected
• ɸD= density log porosity
• ɸDshale= density log porosity in a nearby shale
• Vshale= shale volume

Calculate Density Log Porosity (ɸde) - Shale Corrected- Schlumberger (1975)
ɸd: Decimal		ɸdshale: Decimal
Vsh: Decimal

Made by Henry Herrera

Calculate Neutron Porosity - Shale Corrected (Schlumberger, 1975)

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Neutron Porosity (ɸne)- Shale Corrected- (Schlumberger, 1975)

In 1975, Schlumberger also proposed an equation for the calculation of neutron derived porosity including shale corrections, which takes into account the porosity value in nearby shale and shale volume. The expression is the following:

Where:
• ɸNe= shale-corrected neutron porosity
• ɸN= neutron derived porosity
• ɸNshale= neutron porosity at a nearby shale
• Vshale= shale volume

Calculate Neutron Porosity (ɸne) - Shale Corrected- Schlumberger (1975)
ɸn: Decimal		ɸnshale: Decimal
Vsh: Decimal

Made by Henry Herrera