Stress dependent thermal pressurization of a fluid-saturated rock

Abstract

Temperature increase in saturated porous materials under undrained conditions leads to thermal pressurization of the pore fluid due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. This increase in the pore fluid pressure induces a reduction of the effective mean stress and can lead to shear failure or hydraulic fracturing. The equations governing the phenomenon of thermal pressurization are presented and this phenomenon is studied experimentally for a saturated granular rock in an undrained heating test under constant isotropic stress. Careful analysis of the effect of mechanical and thermal deformation of the drainage and pressure measurement system is performed and a correction of the measured pore pressure is introduced. The test results are modelled using a non-linear thermo-poro-elastic constitutive model of the granular rock with emphasis on the stress-dependent character of the rock compressibility. The effects of stress and temperature on thermal pressurization observed in the tests are correctly reproduced by the model

Effect of porosity on the thermal expansion coefficient: A discussion of the paper ‘Effects of mineral admixtures on the thermal expansion properties of hardened cement paste’ by Z.H. Shui, R. Zhang, W. Chen, D. Xuan, Constr. Build. Mater. 24 (9) (2010) 1761–1767

“…where V V The experimental evaluation of thermal expansion coefficient should be performed under controlled drainage conditions to measure either the drained or the undrained thermal expansion coefficient [2] [7].…”

Thermo- and hydro-mechanical processes along faults during rapid slip

“…Because of the relatively low thermal conductivity of most rocks, and the relatively high shear stresses which they support at frictional micro-contacts, they are in fact susceptible to weakening by flash heating starting at sliding rates as low as 0.1 to 0.3 m/s, which is well less than the average slip rate of ∼1 m/s (Heaton, 1991) Thermo-and hydro-mechanical processes along faults during rapid slip 5 inversions for large earthquakes. Thermal pressurization, process (2), has independent roots in the literature on large landslides (Habib, 1967(Habib, , 1975Anderson, 1980;Voigt and Faust, 1982;Vardoulakis, 2002;Veveakis et al, 2007;Goren and Aharonov, 2009) and that on earthquakes (Sibson, 1973;Lachenbruch, 1980;Smith, 1985, 1987;Lee and Delaney, 1987;Andrews, 2002;Wibberley, 2002;Noda and Shimamoto, 2005;Sulem et al, 2005;Rice, 2006;Rempel and Rice, 2006;Ghabezloo and Sulem, 2008;Noda et al, 2009).…”

Thermomechanical Behavior of Late Indo-Chinese Granodiorite under High Temperature and Pressure

“…Equations (4) and (5) describe the change law of the heating expansion of the rock pore fluid, and the heating expansion of rock is related to the rock solid particles and the rule of thermal expansion of the skeleton. The rock is composed of a variety of minerals; hence, the solid thermal expansion coefficient of rock can be calculated using the coefficient of thermal expansion of the composition [33][34][35]. For example, in a solid phase composed of two kinds of minerals, the coefficient of thermal expansion ( eff ) can be estimated by the following equation:…”