Author(s): Jinchang Sheng; J. Liu; Wc Zhu; D. Elsworth
Linked Author(s): Jianwei Liu
Keywords: No Keywords
Abstract: A fully-coupled thermo-poroelastic model is applied to examine the nonlinear influence of forced convection on the pressures, temperatures, and stresses that may develop in porous rocks with compressible constituents. The fluid and solid media are considered in thermal equilibrium. The geometry of a spherical cavity subject to the non-isothermal forced fluid injection is used as an analog to examine the relative magnitude of the convective influence. The model is validated against available solutions, and then applied to determine the absolute and relative difference in the resulting pressure, temperature and stress fields which result when convection is included in the analysis, versus when it is ignored. In all cases, thermal convection has little influence on fluid pressures. The influence of convection on temperatures and thermally-induced stresses may be significant, and increases as the ratio of fluid diffusivity to thermal diffusivity increases. With the mechanical and thermal properties of porous rocks constrained within relatively narrow limits, the influence of permeability has the greatest variation, and hence influence on this ratio of fluid to thermal diffusivity. For the selected geometry, threshold permeabilities of the order of 10-18m2 denote the regime where convective effects are significant. The influence is greatest away from the conduction-dominated regime at the cavity wall. Beyond this zone, the influence of convection in augmenting temperature and stress increases linearly with an increase in permeability, and are of significant magnitude. Where permeabilities are conditioned by thermal stresses, this feedback may result in an amplified effect. 1
Year: 2007