a: Tortuosity factor

m: Cementation exponent

Comments

1.0

2.0

Carbonates*

0.81

2.0

Consolidated sandstones*

0.62

2.15

Unconsolidated sands (Humble Formula)*

1.45

1.54

Average sands (Carothers, 1968)

1.65

1.33

Shaly sands (Carothers, 1968)

1.45

1.70

Calcareous sands (Carothers, 1968)

0.85

2.14

Carbonates (Carothers , 1968)

2.45

1.08

Pliocene sands,, southern California

(Carothers & Porter, 1970)

1.97

1.29

Miocene sands, Texas-Louisiana Gulf Coast

(Carothers & Porter, 1970)

1.0

${\varnothing }^{\left(2.05-\varnothing \right)}$

Clean granular formations (Sethi, 1979)