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→Why kro or krg is less than kab
==Why k<sub>ro</sub> or k<sub>rg</sub> is less than k<sub>ab</sub>==
==Why k<sub>ro</sub> or k<sub>rg</sub> is less than k<sub>ab</sub>==
[[file:predicting-reservoir-system-quality-and-performance_fig9-26.png|thumb|{{figure number|1}}See text for explanation.]]
[[file:predicting-reservoir-system-quality-and-performance_fig9-26.png|300px|thumb|{{figure number|1}}When a sample contains oil or gas and water (where water wets the grain surface), the pore throat size (B) for oil or gas flow is less than the absolute pore throat size (A). The thickness of the water layer coating the grains is proportional to the S<sub>w</sub> of the rock. In other words, as [[buoyancy pressure]] increases, S<sub>w</sub> decreases and the effective size of the pore throat for oil or gas flow (B) increases.]]
A pore system saturated 100% with any fluid transmits that fluid at a rate relative to the pore throat size and the pressure differential. In the drawing in [[:file:predicting-reservoir-system-quality-and-performance_fig9-26.png|Figure 1]], the absolute pore throat size (A) is noted as the distance between grain surfaces. When a sample contains oil or gas and water (where water wets the grain surface), the pore throat size (B) for oil or gas flow is less than the absolute pore throat size (A). The thickness of the water layer coating the grains is proportional to the S<sub>w</sub> of the rock. In other words, as [[buoyancy pressure]] increases, S<sub>w</sub> decreases and the effective size of the pore throat for oil or gas flow (B) increases.
A pore system saturated 100% with any fluid transmits that fluid at a rate relative to the pore throat size and the pressure differential. In the drawing in [[:file:predicting-reservoir-system-quality-and-performance_fig9-26.png|Figure 1]], the absolute pore throat size (A) is noted as the distance between grain surfaces. When a sample contains oil or gas and water (where water wets the grain surface), the pore throat size (B) for oil or gas flow is less than the absolute pore throat size (A). The thickness of the water layer coating the grains is proportional to the S<sub>w</sub> of the rock. In other words, as [[buoyancy pressure]] increases, S<sub>w</sub> decreases and the effective size of the pore throat for oil or gas flow (B) increases.