Pore structure characteristics of ultra-low permeability reservoirs are studied in this paper. The impact of pore structure characteristics on permeability and reservoir development effect is analyzed by conventional and constant-rate mercury penetration experiments. The results show that the frequency curve of pore radius distribution of ultra-low permeability reservoirs has little change with permeability. The average pore radius in ultra-low permeability reservoirs with different permeability levels had little difference, and its distribution ranges from 98.5 to 110.1 μm. With decrease of permeability, the frequency distribution curves of throat radius and pore-throat ratio change significantly. The peak value of throat radius curve moves to the left and increases significantly, and the average throat-radius distribution decreases from 2.33 to 0.91 μm. However, the impact of pore-throat ratio on permeability is contrary to that of throat radius. Both throat radius and pore-throat ratio has strong correlation with permeability, and they are in exponential relationship. With the in-depth study, it is found that seepage capacity of reservoirs is restricted mainly by throat radius and pore-throat ratio. When throat radius decreases to less than 1 μm and pore-throat ratio increases more than 130, permeability decreases sharply and obviously. When permeability is less than 2 × 10⁻³μm², the proportion of fine throats and medium throats under the condition of effective water injection is significantly lower, and the production of single well and the recovery efficiency by water flooding in ultra-low permeability reservoirs are low. The study explains effectively the fundamental reason for the poor efficiency of production and recovery of ultra-low permeability reservoirs from the mechanism.

研究了超低渗透油藏的孔隙结构特征。通过常规和恒速汞渗透实验分析了孔隙结构特征对渗透率和储层开发效果的影响。结果表明，超低渗透储层孔隙半径分布的频率曲线随渗透率变化不大。不同渗透率水平的超低渗透储层的平均孔隙半径差异不大，分布范围为98.5〜110.1μm。随着渗透率的降低，喉道半径和孔喉比的频率分布曲线发生明显变化。喉咙半径曲线的峰值向左移动并显着增加，平均喉咙半径分布从2开始减小。33至0.91μm。但是，孔喉比对渗透率的影响与喉径相反。喉径和孔喉比都与渗透率有很强的相关性，并且呈指数关系。通过深入研究，发现储层的渗流能力主要受喉径和孔喉比的限制。当喉道半径减小到小于1μm且孔喉比增加到130以上时，渗透率急剧下降且明显。磁导率小于2×10时 研究发现，储层的渗流能力主要受喉径和孔喉比的限制。当喉道半径减小到小于1μm且孔喉比增加到130以上时，渗透率急剧下降且明显。磁导率小于2×10时 研究发现，储层的渗流能力主要受喉径和孔喉比的限制。当喉道半径减小到小于1μm且孔喉比增加到130以上时，渗透率急剧下降且明显。磁导率小于2×10时^-3微米²，细的喉咙和有效的水喷射的条件下介质喉部的比例显著低，且生产单井和在超低渗透油藏通过水驱回收效率是低的。该研究有效地解释了超低渗透储层生产和开采效率低下的根本原因。