Characterization of spatial porosity and mineral distribution of crystalline rock using X-ray micro computed tomography, C-14-PMMA autoradiography and scanning electron microscopy

Mikko Voutilainen, Arttu Miettinen, Paul Sardini, Joni Parkkonen, Juuso Sammaljärvi, Björn Gylling, Jan-Olof Selroos, Maarit Yli-Kaila, Lasse Koskinen, Marja Siitari-Kauppi

Research output: Contribution to journalArticleScientificpeer-review

Abstract

The spatial porosity and mineral distribution of geological materials strongly affects transport processes in them. X-ray micro computed tomography (X-mu CT) has proven to be a powerful tool for characterizing the spatial mineral distribution of geological samples in 3-D. However, limitations in resolution prevent an accurate characterization of pore space especially for tight crystalline rock samples and 2-D methods such as C-14-polymethylmethacrylate (C-14-PMMA) autoradiography and scanning electron microscopy (SEM) are needed. The spatial porosity and mineral distributions of tight crystalline rock samples from Aspo, Sweden, and Olkiluoto, Finland, were studied here. The X-mu CT were used to characterize the spatial distribution of the main minerals in 3-D. Total porosities, fracture porosities, fracture densities and porosity distributions of the samples were determined using the C-14-PMMA autoradiography and characterization of mineral-specific porosities were assisted using chemical staining of rock surfaces. SEM and energy dispersive X-ray spectroscopy (EDS) were used to determine pore apertures and identify the minerals. It was shown that combination of the different imaging techniques creates a powerful tool for the structural characterization of crystalline rock samples. The combination of the results from different methods allowed the construction of spatial porosity, mineral and mineral grain distributions of the samples in 3-D. These spatial distributions enable reactive transport modeling using a more realistic representation of the heterogeneous structure of samples. Furthermore, the realism of the spatial distributions were increased by determinig the densities and porosities of fractures and by the virtual construction heterogeneous mineral distributions of minerals that cannot be separated by X-mu CT.
Original languageEnglish
JournalApplied Geochemistry
Volume101
Pages (from-to)50-61
Number of pages12
ISSN0883-2927
DOIs
Publication statusPublished - Feb 2019
MoE publication typeA1 Journal article-refereed

Fields of Science

  • C-14-PMMA autoradiography
  • CONNECTED POROSITY
  • Crystalline rock
  • Crystalline rocks
  • DIFFUSION EXPERIMENT
  • Energy dispersive X-ray spectroscopy
  • FRACTURES
  • Heterogeneity
  • IMPREGNATION
  • INTERFACE
  • MICROTOMOGRAPHY
  • OLKILUOTO
  • Pore structure
  • Porosity
  • RESOLUTION
  • SCALE
  • SIMULATION APPROACH
  • Scanning electron microscopy
  • X-ray micro computed tomography
  • 116 Chemical sciences
  • 1171 Geosciences

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