Laboratory Measurement of the Permeability of Selma Chalk Using an Improved Experimental Technique

Abstract

The permeabilities to water of 12 monolithic specimens of Selma chalk were determined in the laboratory using an apparatus featuring a micro-syringe pump which could be operated in either the controlled flow or controlled output pressure mode. Specimens 0.4 in. dia. x 2 in. long were diamond-core drilled from large blocks of Selma chalk obtained from a surface mine at Epes, AL. The mean pore radius of the chalk was found to be about 0.15 urn, and the specific surface was 13.9 m2/g. The specimens were mounted with epoxy in thick-walled cylindrical specimen holders under vacuum to assure that the epoxy penetrated a short distance into the specimens to prevent the possibility of liquid bypassing. Permeability values were found to range from 3.47 x 10"8 to 1.68x 10'7 cm/s -within the range of values reported by other investigators. There was some indication that the permeability in the direction parallel to the chalk bedding plane was greater than that in the direction perpendicular to it. This work represents the only study published in the open literature in which measured values of permeabilities of monolithic Selma chalk specimens to water are reported.