Leverett J-function

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In petroleum engineering, the Leverett J-function is a dimensionless function of water saturation describing the capillary pressure,[1]

J(S_w) = \frac{p_c(S_w) \sqrt{k/\phi}}{\gamma \cos \theta}

where S_w is the water saturation measured as a fraction, p_c is the capillary pressure (in pascal), k is the permeability (measured in ), \phi is the porosity (0-1), \gamma is the surface tension and \theta is the contact angle. The function is important in that it is constant for a given saturation within a reservoir, thus relating reservoir properties for neighboring beds.

The Leverett J-function is an attempt at extrapolating capillary pressure data for a given rock to rocks that are similar but with differing permeability, porosity and wetting properties. It assumes that the porous rock can be modelled as a bundle of non-connecting capillary tubes, where the factor \sqrt{k/\phi} is a characteristic length of the capillaries' radii.

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References[edit]

  1. ^ M.C. Leverett (1941). "Capillary behaviour in porous solids". Transactions of the AIME (142): 159–172. 

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