Quantifying the Porosity of Crystalline Rocks by In Situ and Laboratory Injection Methods

Minerals

Markus Leuenberger¹  Kunio Ota²  Marja Siitari-Kauppi³  Andreas Möri⁴  Martin Mazurek⁴  Florian Eichinger⁴ 

[1] Climate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland;Geological Isolation Research and Development Directorate, Japan Atomic Energy Agency (JAEA), Tokai 319-1194, Ibaraki, Japan;Laboratory of Radiochemistry, Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland;Rock-Water Interaction, Institute of Geological Sciences, University of Bern, 3012 Bern, Switzerland;

关键词: crystalline rock;    matrix porosity;    connected porosity;    in situ experiment;    laboratory porosity determination;   

DOI  :  10.3390/min11101072

来源: DOAJ

【 摘 要 】

The porosity and pore geometry of rock samples from a coherent granodioritic rock body at the Grimsel Test Site in Switzerland was characterised by different methods using injection techniques. Results from in situ and laboratory techniques are compared by applying innovative in situ resin impregnation techniques as well as rock impregnation and mercury injection under laboratory conditions. In situ resin impregnation of the rock matrix shows an interconnected pore network throughout the rock body, consisting mainly of grain-boundary pores and solution pores in magmatic feldspar, providing an important reservoir for pore water and solutes, accessible by diffusion. Porosity and pore connectivity do not vary as a function of distance to brittle shear zones. In situ porosity was found to be about 0.3 vol.%, which is about half the porosity value that was determined based on rock samples in the laboratory. Samples that were dried and impregnated in the laboratory were affected by artefacts created since core recovery, and thus showed higher porosity values than samples impregnated under in situ conditions. The extrapolation of laboratory measurements to in situ conditions requires great care and may not be feasible in all cases.

【 授权许可】

Unknown