Effect of High Temperature on Physical and Mechanical Properties of Clay Shales (Caprock)

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2022-06-03
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Abstract
The complex structure of heavy crude oil and bitumen requires enhanced oil recovery methods such as cyclic steam stimulation and steam-assisted gravity drainage to recover effectively. These methods are operated at high temperature ranges. Thus, it is crucial to understand the effect of high temperatures on such operations. This thesis aimed to investigate the changes in physical and mechanical properties of clay shale caprock due to pre-heating under high temperatures. For this purpose, intact clay shale cores were recovered from a site near Long Lake in Alberta. To investigate the effect of pre-heating on clay shale's strength and deformation characteristics twelve samples were trimmed and prepared. Samples were pre-heated up to 20, 150, 300 and 600 °C and thereafter cooled down to ambient temperature naturally. The variation of mechanical properties of clay samples due to the pre-heating was examined in triaxial compression tests. Changes in the composition and crystalline structure of the clay samples were determined through X-ray fluorescence and X-ray diffraction analysis. The experimental results indicated clay samples becoming stiffer (with increased Young’s modulus and lowered Poisson’s ratio) with increasing temperature. Also, the friction angle and cohesive strength of the clay sample increased with temperature. These findings indicate an increasing trend in the mechanical strength of clay samples with temperature. The failure of the clay samples at low confining pressure was mainly due to shear dilation, while compression was the cause of failure at higher confinement pressure.
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Citation
Dovletov, S. (2022). Effect of High Temperature on Physical and Mechanical Properties of Clay Shales (Caprock) (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.