Helium-mass-spectrometry-permeameter for the measurement of permeability of low permeability rock with application to triaxial deformation conditions

S. J. Bauer, M. Y. Lee, W. P. Gardner

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

A helium leakage detection system was modified to measure gas permeability on extracted cores of nearly impermeable rock. Here we use a Helium - Mass - Spectrometry - Permeameter (HMSP) to conduct a constant pressure, steady state flow test through a sample using helium gas. Under triaxial stress conditions, the HMSP can measure flow and estimate permeability of rocks and geomaterials down to the nanodarcy scale (10-21 m2). In this study, measurements of flow through eight shale samples under hydrostatic conditions were in the range of 10-7 to 10-9 Darcy. We extend this flow measurement technology by dynamically monitoring the release of helium from a helium saturated shale sample during a triaxial deformation experiment. The helium flow, initially extremely low, consistent with the low permeability of shale, is observed to increase in advance of volume strain increase during deformation of the shale. This is perhaps the result of microfracture development and flow path linkage through the microfractures within the shale. Once microfracturing coalescence initiates, there is a large increase in helium release and flow. This flow rate increase is likely the result of development of a macrofracture in the sample, a flow conduit, later confirmed by post-test observations of the deformed sample. The release rate (flow) peaks and then diminishes slightly during subsequent deformation; however the post deformation flow rate is considerably greater than that of undeformed shale.

Original languageEnglish
Title of host publication49th US Rock Mechanics / Geomechanics Symposium 2015
PublisherAmerican Rock Mechanics Association (ARMA)
Pages379-385
Number of pages7
ISBN (Electronic)9781510810518
StatePublished - 2015
Event49th US Rock Mechanics / Geomechanics Symposium - San Francisco, United States
Duration: Jun 29 2015Jul 1 2015

Publication series

Name49th US Rock Mechanics / Geomechanics Symposium 2015
Volume1

Conference

Conference49th US Rock Mechanics / Geomechanics Symposium
Country/TerritoryUnited States
CitySan Francisco
Period06/29/1507/1/15

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