Abstract:In order to study the mechanism of the effect of temperature and effective stress on permeability,the porosity and permeability tests for sandstone were conducted at various temperature and effective stress levels. The test results show that both the porosity and permeability of sandstone samples decrease with the increasing effective stress at a fixed temperature level,but the decreasing extent of porosity is much smaller than that of permeability. At a fixed effective stress level,when temperature increases from 20℃ to 60℃,the decreasing extent of the permeability of sandstone samples is about 55.81%–73.85%,but the variation range of porosity is less than 3%. According to the analysis of test results,the mechanism of the effect of temperature and effective stress on the permeability of sandstone is proposed. As far as the sandstone concerned,the effect of effective stress on permeability lies in pressure effect of effective stress on pore,especially on throat,and that of temperature lies in aggravating disaggregation of clay mineral with rising temperature and pressure effect of skeleton expansion on throat. The disaggregation of clay mineral is probably the most important factor.