Effects of pore fluid chemistry on stable sliding of Berea sandstone

Dunning, Jeremy; Miller, Marcus

doi:10.1007/bf00874611

Cited by 16 publications

(10 citation statements)

References 16 publications

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“…A similar influence of brine saturation on sandstone has been reported by Rathnaweera, Ranjith and Perera [28]. The reduction of rock strength with NaCl in the pore fluid possibly occurs for two main reasons: (1) the adsorption of NaCl molecules into the rock matrix causes the surface energy to be reduced, reducing the fracturing strength [35] and, (2) NaCl creates chemical corrosion of rock grain [36][37][38] and its cementation phase, which eventually reduce the rock strength [39]. However, there is also a positive influence of NaCl, as a high concentration of NaCl in the pore fluid causes NaCl crystals to be precipitated in the rock mass pore space [28,40], and these NaCl crystals create additional load-bearing surfaces in the rock mass, increasing its strength.…”

Section: Evaluation Of Brittleness Of Rock Samplessupporting

confidence: 54%

Effects of Pore Fluid Chemistry and Saturation Degree on the Fracability of Australian Warwick Siltstone

et al. 2018

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Fracability of unconventional gas reservoirs is an important parameter that governs the effectiveness of subsequent gas extraction. Since reservoirs are saturated with various pore fluids, it is essential to evaluate the alteration of fracability of varyingly saturated rocks. In this study, varyingly saturated (dry, water, and brine with 10%, 20% and 30% NaCl by weight) siltstone samples were subjected to uniaxial compressive loading to evaluate their fracability variation. Acoustic emission (AE) and ARAMIS photogrammetry analyses were incorporated to interpret the crack propagation. SEM analysis was carried out to visualize the micro-structural alterations. Results show that siltstone strength and brittleness index (BI) are reduced by 31.7% and 46.7% after water saturation, due to water-induced softening effect. High NaCl concentrations do not reduce the siltstone strength or brittleness significantly but may contribute to a slight re-gain of both values (about 3–4%). This may be due to NaCl crystallization in rock pore spaces, as confirmed by SEM analysis. AE analysis infers that dry siltstone exhibits a gradual fracture propagation, whereas water and brine saturated specimens exhibit a hindered fracturing ability. ARAMIS analysis illustrates that high NaCl concentrations causes rock mass failure to be converted to shear failure from splitting failure, which is in favour of fracability.

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Section: Evaluation Of Brittleness Of Rock Samplessupporting

confidence: 54%

Effects of Pore Fluid Chemistry and Saturation Degree on the Fracability of Australian Warwick Siltstone

et al. 2018

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“…Qualitatively, critical state models predict post-failure strain softening in dilatant rocks and strain hardening in compacting materials as has often been observed in sandstones (among others, see BernabC & Brace 1990). It should also be noted that some samples were significantly weaker when saturated with distilled water (see also Rutter & Mainprice 1978;Dunning & Miller 1984;Feucht & Logan 1990). However, sensitivity to water was, here, only clearly observed in the samples near failure.…”

Section: Triaxial Testsmentioning

confidence: 91%

Experimental Observations of the Elastic and Inelastic Behaviour of Porous Sandstones

Bernabé¹,

Fryer

Shively

1994

Geophysical Journal International

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S U M M A R YIn order to investigate the mechanical behaviour of porous sandstones, a number of mechanical tests, including creep tests, were run o n eight sandstones ranging from 17 to 30 per cent porosity, in both vacuum-dry and water-saturated conditions. To interpret the data it is essential to separate the elastic and inelastic parts of the total strain. Small stress excursions, along which the rock behaved elastically, were performed at discrete intervals along the main stress path. This allowed us to estimate the elastic moduli at various points along the stress/strain curve. We observed that the elastic constants increased significantly with increasing mean stress, but the magnitudes and pressure-dependence of the elastic constants were not consistent with presently proposed grain contact models. Knowing the elastic constants, we computed the elastic and, by difference, the non-elastic parts of the deformation. This study confirms that plasticity models such as those used in soil mechanics can account, at least qualitatively, for many features of the inelastic behaviour of porous sandstones. In particular, we observed the existence of a cap closing the yield surface in the hydrostatic pressure direction. In the relatively low stress range used here, the inelastic behaviour appeared to be controlled by frictional mechanisms rather than by grain fracturing as is commonly observed at higher stress levels. Non-elasticity seemed also to be closely connected to time dependence. Near failure, the creep rates were high and, furthermore, accelerated in the presence of water. Finally, comparison of the elastic moduli measured along different stress paths allowed us to detect and quantify mechanical anisotropy in some of the rocks considered.

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“…Differential pressure and flow rate measurements were used to calculate changes in permeability as the biofilm developed. Two experiments were performed with separate 2.54 cm diameter Berea sandstone cores (97% quartz, 3% accessory clay and opaque minerals) (Dunning and Miller, 1984). Each had an approximate porosity of 22% and permeability of 40 milidarcy.…”

Section: High-pressure Equipment Setupmentioning

confidence: 99%

Biofilm enhanced geologic sequestration of supercritical CO2

Mitchell

Phillips

Hiebert

et al. 2009

International Journal of Greenhouse Gas Control

111

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Mitchell, A. C., Phillips, A., Heibert, R., Gerlach, R., Cunningham, A., Spangler, L. (2009). Biofilm enhanced geologic sequestration of supercritical CO2. International Journal of Greenhouse Gas Control, 3 (1), 90-99. A Mitchell came to AU in 2009. Sponsorship: Zero Emissions Research Technology (ZERT) fund, from the U.S. Department of Energy (DOE), Award No. DE-FC26-04NT42262.In order to develop subsurface CO2 storage as a viable engineered mechanism to reduce the emission of CO2 into the atmosphere, any potential leakage of injected supercritical CO2 (SC-CO2) from the deep subsurface to the atmosphere must be reduced. Here, we investigate the utility of biofilms, which are microorganism assemblages firmly attached to a surface, as a means of reducing the permeability of deep subsurface porous geological matrices under high pressure and in the presence of SC-CO2, using a unique high pressure (8.9 MPa), moderate temperature (32 ?C) flow reactor containing 40 millidarcy Berea sandstone cores. The flow reactor containing the sandstone core was inoculated with the biofilm forming organism Shewanella fridgidimarina. Electron microscopy of the rock core revealed substantial biofilm growth and accumulation under high-pressure conditions in the rock pore space which caused >95% reduction in core permeability. Permeability increased only slightly in response to SC-CO2 challenges of up to 71 h and starvation for up to 363 h in length. Viable population assays of microorganisms in the effluent indicated survival of the cells following SC-CO2 challenges and starvation, although S. fridgidimarina was succeeded by Bacillus mojavensis and Citrobacter sp. which were native in the core. These observations suggest that engineered biofilm barriers may be used to enhance the geologic sequestration of atmospheric CO2.preprintPeer reviewe

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Effects of pore fluid chemistry on stable sliding of Berea sandstone

Cited by 16 publications

References 16 publications

Effects of Pore Fluid Chemistry and Saturation Degree on the Fracability of Australian Warwick Siltstone

Effects of Pore Fluid Chemistry and Saturation Degree on the Fracability of Australian Warwick Siltstone

Experimental Observations of the Elastic and Inelastic Behaviour of Porous Sandstones

Biofilm enhanced geologic sequestration of supercritical CO2

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