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One of the saturation from resistivity models:
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R_t | is defined as:
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\frac{1}{R_t} = \frac{\phi_e^m \, s_w^n }{A R_w} \quad \Rightarrow \quad s_w = \Big ( \frac{A}{\phi_e^m} \; \frac{R_w}{R_t} \Big) ^{1/n} |
where
| formation water saturation | |||||
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| effective porosity | |||||
| specific electrical resistivity from OH logs | |||||
| specific electrical resistivity of formation water | |||||
| dimensionless constant, characterizing the rock matrix contribution to the total electrical resistivity | 0.5 ÷ 1, default value is 1 for sandstones and 0.9 for limestones | ||||
| formation matrix cementation exponent | 1.5 ÷ 2.5, default value is 2 | ||||
| formation matrix water-saturation exponent | 1.5 ÷ 2.5, default value is 2 |
Archie model is usually used in:
- high permeable clean sands with low or no shaliness
- high permeable clean limestones with low or no shaliness
See Also
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Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petrophysics
Well & Reservoir Surveillance / Well logging / Reservoir Data Logs (RDL) / Formation Resistivity Log @model