This paper evaluates the variation characteristics of micro-pore throats and movable fluids in ultra-low permeability sandstone reservoirs of Yanchang Formation in Ordos Basin quantitatively based on the experimental resuits from NMR and constant-rate mercury injection. The analysis shows that the parameters of movable fluids and throat characteristics change greatly, and the difference of pore parameters is small. The influences of micro porethroats on movable fluid parameters are mainly reflected by the variation of throat characteristics: the smaller the throat radius becomes, the faster the movable fluid parameters attenuate. High pore throat ratio and wide-ranged distribution are the main reasons of low content and poor producing degree of movable fluids in ultra-low permeability sandstone reservoirs. The correlation of mercury-intake saturation in pores and throats and movable fluid parameters appears to be favorable, indicating that the larger the effective pore and throat volume become, the higher themontent of movable fluids,and the larger prodicing degree.%基于核磁共振、恒速压汞实验结果,对鄂尔多斯盆地延长组特低渗透砂岩储层的微观孔喉与可动流体变化特征进行了定量评价.分析表明,特低渗透砂岩储层可动流体参数、喉道特征参数变化幅度大,孔隙参数差异小.微观孔喉对可动流体参数的影响主要体现在喉道特征的变化上,喉道半径越小,可动流体参数衰减越快.孔喉比较大、分布范围宽是特低渗透砂岩储层可动流体含量低,可动用程度差的主要原因之一.孔隙、喉道进汞饱和度与可动流体参数之间均表现出了非常好的相关性,表明有效孔隙、喉道体积越大,可动流体含量越高,可动用程度越大.
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