中文摘要：

实验选取4块大庆低渗透砂岩岩心，渗透率分布0．1～110^-3μm3，利用毛细管平衡法研究了岩样的非达西渗流过程。本实验周期长达3个月，精确度高，实验结果表明：低渗砂岩岩样存在启动压力梯度，流量一压力梯度曲线呈上凹变化，且随着气测渗透率的降低，曲线逐渐右移；流度越大，启动压力梯度越小，同时通过建立低渗岩样的启动压力梯度和流度的双对数坐标曲线，回归得到了启动压力梯度和流度的关系；实验后期表现出异常的渗吸现象，通过计算渗吸量与孔隙体积的比值（即渗吸度），得到平均渗吸度在13％左右，这对于提高低渗油藏的采收率有着重要意义。

英文摘要：

Four ultra - low permeability sandstone cores, which were taken from Daqing Oilfield,were used in the experiments. The permeability distribution of the cores is between （0. 1 - 1 ） ×10^-3μm2. The capillary pressure equilibrium method was employed to study on the non - Darcy seepage process in the cores. The period of experiment with high preci- sion last as long as three months. The experimental results indicated that the low permeability sandstone has threshold pres- sure gradient, the correlative curve between the flow rate and pressure gradient shows a concave upward change ,while the gas permeability reduces , the correlative curve gradually shifts to the right;the bigger the mobility is, the smaller the threshold pressure gradient is. The mathematical relation between threshold pressure gradient and mobility was established by log - log coordinate curve ; abnormal imbibitional phenomenon appeared in later stage of the experiment. The average imbibition curvature, which is ratio of imbibitional volume and pore volume,is around 13 percent. It is very important for the low permeability reservoirs to improve the recovery ratio.