Permeability of Clays Under Organic Permeants

Abstract

A magnesium montmorilionite and a kaolinite clay are subjected to organic and inorganic permeants to study the changes in permeability caused by the reaction between clays and permeants. The permeants are acetic acid, aniline, methanol, and xylene. Tests are conducted in specially designed and constructed flexible wall permeameters that provide precise measurements of pressures and flows. Increases in clay permeability due to clay‐permeant chemical reactions are measured to be on the order of two to three times the original permeability. This is in contrast to the 100 to 1,000 times increases reported by others. The writers believe that the large increases reported by others is probably due to the use of fixed‐wall permeameters. The writers' results show that methanol doubles the permeability of montmorilionite. Acetic acid reacts with the carbonates in montmorilionite and liberated carbon dioxide. The resulting loss of mass triples the clay's permeability. Aniline and xylene will not flow through saturated montmorilionite but will flow through saturated kaolinite at reduced flow rates. Hydraulic fracturing of the montmorilionite occurred when methanol passed through it under a high gradient and low confining pressure.