Laboratory experiments for diffusion transport processes in fractured chalk

Effective diffusivities of various artificial tracers of 0.59-2.78 E-6 cm2 s-1 for Maastrichtian chalk (Danish), and of 0.919-6.22 E-7 cm2 s-1 for Eocene (Israeli) chalk samples were obtained with the help of through-diffusion experiments. The variations can be explained by Archie's law with a distinct cementation factor for the chalk varieties tested. The Eocene chalk shows small relative diffusivity resulting in an extremely large m value of 3.3 due to its narrow and wide range of pore-throat sizes. The rock capacity factors obtained indicate retardati- on of pyranine in all chalk samples and batch experiments performed in parallel confirmed the sorptive behaviour of pyranine in chalk.