Reservoir and lithofacies shale classification based on NMR logging

Hongyan Yu*, Zhenliang Wang, Fenggang Wen, Reza Rezaee, Maxim Lebedev, Xiaolong Li, Yihuai Zhang, Stefan Iglauer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Shale gas reservoirs have fine-grained textures and high organic contents, leading to complex pore structures. Therefore, accurate well-log derived pore size distributions are difficult to acquire for this unconventional reservoir type, despite their importance. However, nuclear magnetic resonance (NMR) logging can in principle provide such information via hydrogen relaxation time measurements. Thus, in this paper, NMR response curves (of shale samples) were rigorously mathematically analyzed (with an Expectation Maximization algorithm) and categorized based on the NMR data and their geology, respectively. Thus the number of the NMR peaks, their relaxation times and amplitudes were analyzed to characterize pore size distributions and lithofacies. Seven pore size distribution classes were distinguished; these were verified independently with Pulsed-Neutron Spectrometry (PNS) well-log data. This study thus improves the interpretation of well log data in terms of pore structure and mineralogy of shale reservoirs, and consequently aids in the optimization of shale gas extraction from the subsurface.

Original languageEnglish
Pages (from-to)202-209
Number of pages8
JournalPetroleum Research
Volume5
Issue number3
DOIs
Publication statusPublished - Sept 2020
Externally publishedYes

Keywords

  • Composition
  • NMR logging
  • Pore size distribution
  • Shale gas

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