Temperature effect on low permeability porous media filled with water at high pressures

This article analyses the influence of small temperature variations in a rigid porous medium with ultra-low permeability, in which the natural pores are filled with water at high pressure. The basic idea is to verify the possibility of inducing the process of hydraulic fracturing of such kind of water wells with a small increase of temperature. It is shown, both theoretically and experimentally that, at high pressures and temperatures, hydraulic fracture may be induced by very small temperature variations. Due to the compressibility and depending on the fluid temperature and pressure, a small increase of temperature in a pore may cause a pressure surge that may eventually lead the solid matrix to failure. Hydrostatic experiments performed in a slightly deformable system filled with water with an initial internal pressure at temperatures around 353.15 K have shown that small temperature variations can strongly affect pressure. An equation of state is proposed to explain this phenomenon and theoretical predictions are in good agreement with experimental results also presented in this paper.