Permeability in Rotliegend gas sandstones to gas and brine as predicted from NMR, mercury injection and image analysis

Esther Rosenbrand, Ida Lykke Fabricius, Quentin Fisher, Carlos Grattoni

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Permeability characterisation of low permeability, clay-rich gas sandstones is part of production forecasting and reservoir management. The physically based Kozeny (1927) equation linking permeability with porosity and pore size is derived for a porous medium with a homogeneous pore size, whereas the pore sizes in tight sandstones can range from nm to μm. Nuclear magnetic resonance (NMR) transverse relaxation was used to estimate a pore size distribution for 63 samples of Rotliegend sandstone. The surface relaxation parameter required to relate NMR to pore size is estimated by combination of NMR and mercury injection data. To estimate which pores control permeability to gas, gas permeability was calculated for each pore size increment by using the Kozeny equation. Permeability to brine is modelled by assuming a bound water layer on the mineral pore interface. The measured brine permeabilities are lower than predicted based on bound water alone for these illite rich samples. Based on the fibrous textures of illite as visible in electron microscopy we speculate that these may contribute to a lower brine permeability.
Original languageEnglish
JournalMarine and Petroleum Geology
Volume64
Pages (from-to)189-202
Number of pages14
ISSN0264-8172
DOIs
Publication statusPublished - 2015

Keywords

  • Bound water
  • Image analysis
  • NMR
  • Permeability
  • Tight sandstone

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