Ultrasonic velocity measurements on limestones from the Portland group : correlation with porosity and other lithological factors

Abstract

Laboratory determination of velocity and porosity have been made on nearly 900 core-specimens taken from 72 surface-outcrop samples of limestones from the Portland Group of southern England. These limestones have been petrographically classified into four basic types - Sparites, Micrites, Chalks and microsparites, partly following criteria used by Folk (1962). Simple linear-regression-analysis has been used to establish empirical relationships between velocity and porosity for each of the four limestone-types. Additionally, multiple linear-regression-analysis was employed to determine the extent to which 21 other physical parameters, mainly petrographic, are related to velocity. 245 members of the core- specimen population were used for this aspect of the work. Representative specimens of the limestone-types have been analysed using reflected-light microscopy and scanning-electron microscopy, in order to provide information on type, size, distribution, morphology and orientation of the pores. Porosity is shown to be the major cause of velocity-variation in all four limestone-types, with the exception of low-porosity Micrites (< 12% porosity). Propagation of the elastic-waves appears to be confined to the matrix in these low-porosity iiicrites, whereas propagation occurs through both matrix and pores in the other types. A limited study of the effect of water-saturation on velocity supports ths conclusion. 'Planar fabric-elements', in the form of preferred mineral- and/or

More information

Identifiers

Catalogue record

Export record

ASCII CitationAtomBibTeXData Cite XMLDublin CoreDublin CoreEP3 XMLEndNoteHTML CitationHTML CitationHTML ListJSONMETSMODSMPEG-21 DIDLOpenURL ContextObjectOpenURL ContextObject in SpanRDF+N-TriplesRDF+N3RDF+XMLRIOXX2 XMLReferReference ManagerSimple Metadata