Influence of Water Saturation on the Mechanical Behaviour of Low-Permeability Reservoir Rocks

Decheng Zhang, Ranjith Pathegama Gamage, Mandadige Samintha Anne Perera, Chengpeng Zhang and Wanniarachchillage Ayal Maneth Wanniarachchi
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Decheng Zhang: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, Australia
Ranjith Pathegama Gamage: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, Australia
Mandadige Samintha Anne Perera: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, Australia
Chengpeng Zhang: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, Australia
Wanniarachchillage Ayal Maneth Wanniarachchi: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, Australia

Energies, 2017, vol. 10, issue 2, 1-19

Abstract: The influence of water on the mechanical properties of rocks has been observed by many researchers in rock engineering and laboratory tests, especially for sedimentary rocks. In order to investigate the effect of water saturation on the mechanical properties of low-permeability rocks, uniaxial compression tests were conducted on siltstone with different water contents. The effects of water on the strength, elastic moduli, crack initiation and damage thresholds were observed for different water saturation levels. It was found that 10% water saturation level caused more than half of the reductions in mechanical properties. A new approach is proposed to analyze the stress-strain relations at different stages of compression by dividing the axial and lateral stress-strain curves into five equal stress zones, where stress zones 1–5 refer to 0%–20%, 20%–40%, 40%–60%, 60%–80% and 80%–100% of the peak stress, respectively. Stress zone 2 represents the elastic range better than stress zone 3 which is at half of the peak stress. The normalized crack initiation and crack damage stress thresholds obtained from the stress-strain curves and acoustic emission activities averaged 31.5% and 83% of the peak strength respectively. Pore pressure is inferred to take part in the deformation of low-permeability siltstone samples, especially at full saturation levels. A change of failure pattern from multi-fracturing to single shear failure with the increase of water saturation level was also observed.

Keywords: water degradation; water saturation level; low-permeability; uniaxial compressive strength (UCS); mechanical properties (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2017
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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