Influence of Confining Stress on Permeability

Numerous studies have shown that confining stress significantly influences low-k rock permeability. Confining stress results in a progressively greater decrease in permeability from routine air permeability values with decreasing routine permeability and with increasing confining stress. This effect has been shown on Council Grove rocks in the previous panel. The strong influence of confining stress is attributed primarily to the decrease in size of the thin, tabular pore throats that interconnect the larger pore bodies. Council Grove rocks exhibit the “classic” exponential decline in permeability with increasing confining stress and the same cube root versus confining stress relationship originally presented by Jones and Owens (1981) for low-k sandstones.