Advertisement

Profiling the In Situ Compressibility of Cretaceous Shale Using Grouted-in Piezometers and Laboratory Testing

  • Laura Smith
  • S. Lee BarbourEmail author
  • M. Jim Hendry
  • D. Elwood
Conference paper
Part of the Springer Series in Geomechanics and Geoengineering book series (SSGG)

Abstract

Grouted-in vibrating wire pressure transducers (VWPs) can be used to measure the in situ constrained (1-D) compressibility (mv) of deep claystone aquitards through measurement of barometric loading efficiency. Measurements of in situ mv for a Cretaceous shale in southern Saskatchewan, Canada, were undertaken using data collected from 27 VWPs installed in multiple boreholes at two sites over depths of 10 to 325 m below ground. The measured mv profiles at both sites produced similar trends of decreasing mv with increasing depth. 1-D consolidation testing was used to measure pre-consolidation pressure (Pc’), compression index (Cc), and the swelling index (Cr) on nine core samples collected from Site 1. These tests yielded Cc values ranging from 0.1–0.5 (\( \bar{x} \) = 0.29 ± 0.12), and Cr from 0.03–0.07 (\( \bar{x} \) = 0.05 ± 0.02). Laboratory measurements of Cc and Cr were used to estimate variations in in situ mv with depth. A theoretical relationship between in situ void ratio (e) and effective stress (σ′) was determined using the laboratory determined Pc’ values, compression indices (Cc, Cr), and measurements of in situ e. Varying the values of Pc’, Cc, or e exerted minor influences on these profiles relative to Cr. The resulting theoretical patterns of in situ mv with depth (or σ′), exhibited a similar pattern to the laboratory and field observations, however to replicate the in situ profiles the Cr values had to be an order of magnitude lower than the laboratory values. The good agreement between the theoretical and measured mv profiles with depth highlight the potential to combine in situ measurements of mv with laboratory consolidation test results to characterize the mechanical properties of deep claystone aquitards and potentially improve upon our understanding of how the stress history of these formation has resulted in their present day geomechanical properties.

Keywords

Void Ratio Stress History Hydrogen Index Compression Index Consolidation Test 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

Funding was provided by NSERC-IRC (184573) and by the Mosaic Company, Cenovus Energy, PotashCorp, and the Saskatchewan Potash Producers Association (MJH).

References

  1. Bjerrum L (1967) Progressive failure in slopes of overconsolidated clay and clay shales. Proc J Soil Mech Found Div 93:1–49. American Society of Civil EngineersGoogle Scholar
  2. Christensen EA (1968a) Pleistocene stratigraphy of the Saskatoon area, Saskatchewan, Canada. Can J Earth Sci 5:1167–1173CrossRefGoogle Scholar
  3. Christensen EA (1968b) A thin till in west-central Saskatchewan. Canada. Can J Earth Sci 5:329–336CrossRefGoogle Scholar
  4. Casagrande A (1936) The determination of the pre-consolidation load and its practical significance. In: Proceedings of the international conference on soil mechanics and foundation engineering. Harvard University Cambridge, pp 60–64Google Scholar
  5. Dawson FM, Evans CG, Marsh R, Richardson R (2008) Uppermost Cretaceous and tertiary strata of the western Canada sedimentary basin. In: Geological atlas of the western Canada sedimentary basin. Canadian Society of Petroleum Geologists and Alberta Research Council, Special Report 4Google Scholar
  6. Jorgensen D (1980) Relationships between basic soils-engineering equations and basic ground-water flow equations, Geological Survey Water-Supply Paper 2064, Washington, DCGoogle Scholar
  7. Peterson R (1958) Rebound in Bearpaw Shale. West Can Bull Geol Soc Am 69:1113–1124CrossRefGoogle Scholar
  8. Sauer KE, Misfeldt GA (1993) Preconsolidation of Cretaceous clays of the western interior basin in southern Saskatchewan. In: Proceeding of the 46th annual Canadian geotechnical conference, Saskatoon, 27–29 September 1993Google Scholar
  9. Smith LA, van der Kamp G, Hendry MJ (2013) A new technique for obtaining high-resolution pore pressure records in thick claystone aquitards and its use to determine in situ compressibility. Water Resour Res 49:732–743. doi: 10.1002/wcwr.20084 CrossRefGoogle Scholar
  10. Smith LA, Barbour SL, Hendry MJ, Novakowski K, van der Kamp G (2016) A multiscale approach to determine hydraulic conductivity in thick claystone aquitards using field, laboratory and numerical modeling methods. Water Resour Res. doi: 10.1002/2015WR018448
  11. Smith LA, Barbour SL, Hendry MJ Profiling the in situ compressibility of Cretaceous shale using grouted-in piezometers and laboratory testing. Can Geotech J. (submitted)Google Scholar
  12. Smith TJ (1978) Consolidation and other geotechnical properties of shales with respect to age and composition. PhD thesis, University of DurhamGoogle Scholar
  13. van der Kamp G, Gale JE (1983) Theory of earth tide and barometric effects in porous formations with compressible grains. Water Resour Res 19(2):538–544CrossRefGoogle Scholar
  14. Vigrass L (2006) Williston basin. Encyclopedia of Saskatchewan. http://esask.uregina.ca/entry/williston_basin.html. Accessed 23 Nov 2015

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Laura Smith
    • 1
  • S. Lee Barbour
    • 2
    Email author
  • M. Jim Hendry
    • 1
  • D. Elwood
    • 2
  1. 1.Department of Geological SciencesUniversity of SaskatchewanSaskatoonCanada
  2. 2.Department of Civil and Geological EngineeringUniversity of SaskatchewanSaskatoonCanada

Personalised recommendations