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Elastic Stiffening of Shale up to 200°C: Insights from High-load Nanoindentation Tests

Lookup NU author(s): Dr Sam Graham, Dr Mohamed Rouainia, Dr Mark IrelandORCiD


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In recent years the use of nanoindentation to study the mechanical properties of shale at the microscale has become popular. Yet, few directly consider the influence of temperature on the elasticity and creep responses. This poses problems when using pre-existing micromechanical data to model shales under more realistic subsurface conditions. We considered three samples from the Haynesville-Bossier shale, USA: a clay-rich Bossier sample and two more quartz and carbonate-rich Haynesville samples to study the indentation modulus, M, hardness H and creep modulus C at the scale of the poro-mineralogical skeletons at temperatures up to 200 °C. We demonstrate that at high-temperatures, there is a marked increase in all mechanical properties of the porous shale composite due to loss of adsorbed water, primarily from the organo-clay matrix. This has implications for future development of nanomechanical protocols where water loss should be controlled to better resemble a sub-surface system. Furthermore, we show that diagenetic factors play a strong role in differentiating the effects of temperature on hardness and creep. This dimension needs greater emphasis in future micromechanical studies since x-ray diffraction-derived mineralogy does not provide information on the microstructural form of a given mineral phase.

Publication metadata

Author(s): Graham SP, Rouainia M, Ireland MT, Aplin AC, Armitage PJ

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: 55th U.S. Rock Mechanics/Geomechanics Symposium

Year of Conference: 2021

Print publication date: 28/06/2021

Online publication date: 18/06/2021

Acceptance date: 02/04/2021

Publisher: OnePetro


Notes: Paper Number: ARMA-2021-1338