Diffusion-induced hydrocarbon migration

The rate and direction of diffusive transport of atoms or molecules in liquids, gases and solids is determined by gradients in chemical potential of the atom or molecule. 

Diffusion through water-saturated source rocks 

The diffusion of hydrocarbons in source rocks is influenced by (Krooss and Leythaeuser, 1988)  

Leythaeuser et al. s (1982) study showed that the composition of the gas accumulated in a reservoir after transportation from a source rock where diffusion was the initial process of primary migration is controlled by three principal factors the initial concentration of the individual hydrocarbons in the source rock, their relative differences in diffusion rates, and the source rock thickness. Diffusion through water-saturated rock is probably a relatively minor primary migration mechanism, in view of the total amounts of 

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