Gas/water Flowing Ability Influence Experimental Study of Permeability Stress Sensibility in Tight Gas Reservoir

Taking cores of P1s and P2h formation from tight gas reservoir in Changqing oilfield as an example,we discuss the gas/water flowing ability and production influence of permeability stress sensibility based on stress sensitivity experiments.The gas/water relative permeability change trend in different confining pressures is studied.The experiment results show that in the same permeability,when the confining pressures increase,core pore throat and bigger pore deformed with compression,which leads to overall drop of gas/water relative permeability.At the same stress condition,the better the pore structure in the process of gas injection,the stronger the gas/water two phase filtration capacity.Gas driving water distribution curve shows that when the confining pressure is large,the water appears soon in the process of gas driving water process,and the gas driving water effect is worse.In the same confining pressure,the higher the reservoir permeability,the later the water appearance in the process of gas driving water,the better the gas driving water effect.In tight gas reservoir,the absolute value changes caused by stress sensibility are not big,but the relative value changes are great.It influences tight reservoir permeability and gas/water flowing characteristics a lot,and its affect on reservoir productivity can not be ignored.