围压和孔隙结构对不同粒级砂岩孔隙度渗透率的影响实验研究

EXPERIMENTAL STUDY ON THE EFFECTS OF CONFINING PRESSURE AND PORE STRUCTURE ON POROSITY AND PERMEABILITY OF SANDSTONES WITH DIFFERENT GRAIN SIZES

孔隙度和渗透率是储层评价的两个重要参数.岩石毛管压力曲线和核磁共振T2谱图是描述储层微观结构特征的重要参数.通过测量不同压力条件下岩心样品的孔隙度和渗透率,得到了孔隙度和渗透率随压力的变化情况.实验结果表明:孔隙度和渗透率随着压力的增加而降低,并且与压力服从对数函数变化规律.不同孔隙度渗透率区间的砂岩样品,孔隙度和渗透率随着压力变化的趋势不同.通过测量不同粒级砂岩样品的毛管压力曲线和核磁共振T2谱图,证实了孔隙结构对孔隙度和渗透率的影响,微观孔隙结构是决定渗透性好坏的关键因素.

By measuring the porosity and permeability of core samples under different pressures,their relations with pressure are obtained. The results show that porosity and permeability decrease as pressure increases and obey the rule of logarithm function. However,the changing trends are quite different for sandstone samples between different intervals of porosity and permeability. The effect of pore structure on porosity and permeability are confirmed through the capillary pressure curve and nuclear magnetic resonance（NMR） T2 spectrogram of sandstone samples with different grain sizes. The microstructure is the key factor that determines permeability.