Thermal influence on flow from a compressible porous medium


  • Robert E. Passwell


The equation of transient flow through a porous medium is dependent upon both the permeability and compressibility of the matrix, two properties that are highly temperature dependent. By formulating this dependence, it is possible to predict the behavior of a consolidating mass subject to specific constant temperature levels. This analysis is extended to predict transient flow behavior for conditions of temperature variations in a given sample, using numerical methods. Temperature increases induced either before or after dissipation of the excess hydrostatic pressure influence the rate of consolidation by increasing the rate of pore pressure dissipation and decreasing the ability of the matrix to assume the stress. An experimental program was established to study the effect of boundary temperature increases on a stressed-saturated clay after pore pressure dissipation. Temperature increases caused immediate volume changes, the magnitudes being primarily dependent upon the magnitude of the temperature change. The magnitude of the initial stress (pore-pressure excess) was seen to have a secondary effect on the magnitude of the volume change. These volume changes are attributed to a transfer of stress between the pore fluid and the matrix, as the increases in temperature increase the pore pressure but decrease the matrix strength.