Porosity 03 : (n) (1) The condition of being porous (such as a rock formation). (2) The ratio of the volume of empty space to the volume of solid rock in a formation, indicating how much fluid a rock can hold
US Department of Labor, Occupational Safety & Health Administration (OSHA), Oil and Gas Well Drilling and Servicing eTool, Washington, DC. This is an abridged version of the Dictionary of Petroleum Terms provided by Petex and the University of Texas Austin, USA 2001. http://www.osha.gov/SLTC/etools/oilandgas/glossary _of_terms/glossary_of_terms_a.html, (Oil Well Drilling Sci and Tech - Amer) {492}