Отправлено: 09.04.13 09:51. Заголовок: A permeability–porosity relationship for mudstones

A permeability–porosity relationship for mudstones
Yunlai Yang, Andrew C. Aplin

The relationship between permeability and porosity for fine-grained clastic sediments (‘‘mudstones’’) is
a key constitutive equation for modelling subsurface fluid flow and is fundamental to the quantification
of a range of geological processes. For a given porosity, mudstone permeability varies over a range of 2–5
orders of magnitude. We show here that much of the range can be explained by variations in lithology,
which we define simply and pragmatically by clay content (mass fraction of particles less than 2 microns
in diameter). Using clay content as the quantitative lithology descriptor, we have used a dataset (clay
content range of 12–97%; porosity range of 0.04–0.78; six orders of magnitude permeability range)
comprising 376 data points to derive a new bedding perpendicular permeability (K, m2),
e= porosity/(1-porosity) relationship as a function of clay content (CF):

At a given porosity, the inclusion of the quantitative litho-
logical descriptor, clay content reduces the predicted range of permeability from 2 to 5 orders of
magnitude to one order.

Marine and Petroleum Geology 27 (2010) 1692–1697