Abstract
Chemical osmosis is a phenomenon which is caused by the behavior of clay layers and mudstones as semipermeable membrane. It is considered that the osmotic behavior can be important for the generation and preservation of abnormal pore pressures in subsurface in the case where solute concentration is different between both sides of the mudstone layer. Abnormal pressures caused by the chemical osmosis are dissipated by diffusion-limited process, and hence, the abnormal pressures can be preserved in geologic time scales. This lecture presents examples of the chemical osmotic processes inferred and/or observed in subsurface environments. Our effort to analyze fundamental processes related to chemical osmosis is also presented. An example result from our experiment clearly shows that the mudstone behaves as semi-permeable membrane. Further study to determine physical properties of mudstones which are related to chemical osmosis is necessary by laboratory experiments presented in this lecture.
