EXPERIMENT ON GAS SEEPAGE MECHANISM IN LOW-PERMEABILITY GAS RESERVOIRS

In view of low-permeability gas reservoir's relatively high water saturation,the experiment method of gas seepage is modified;on the basis of raising the experiment accuracy and combining the experimental data handling method of gas circulation velocity under average pressure gradient,a kind of turning point-type gas seepage curve is discovered,the gas seepage pattern is not same in the different experimental pressure drop area,that is with the augmenting of pressure gradient threshold pressure effect and slippage effect takes the dominant position in turn.On this basis,the differences of gas seepage characteristics under normal pressure and overlay pressure in low seeping water-contented rock core are analyzed by means of further experimental study.The research result is that turning point-type gas seepage curve is the macroscopic manifestation of the two influential factors restraint and contradict each other,i.e.,slipping force and capillary resistance force;and the location of turning point reflects the transformation border of the two influential factors' dominant position.