Impermeable 7 : Rock with passages so small that no effective flow can take place. Note: all manmade and natural substances have some permeability, given high pressure, time, enough surface area and a low permeability fluid
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}