中文摘要：

为明确超低渗透砂岩的剩余油赋存状态,对比评价影响水驱油效率的主要因素,利用改进的核磁共振高压驱替系统开展了水驱油实验.结果表明,实验样品的平均水驱油效率为35.79%,1-10ms的较小孔喉和10-100ms的中等孔喉既是饱和油条件下油的主要分布范围,也是水驱后剩余油的主要赋存空间.10-100ms的中等孔喉动用效果最好,对驱油效率贡献程度最大.水驱油效率受物性、微裂缝、孔喉非均质性和孔喉动用程度的共同影响,孔喉细小,但分布均一的样品有可能取得较好的驱替效果.充分发挥毛细管自吸驱油作用,先有效开发小孔喉,再提高驱替速度开发较大孔喉,有助于提高驱油效率.对于超低渗透砂岩储层而言,要提高整体开发效果,需要各个范围内的孔喉均得到有效动用,改善小孔喉、尤其是含量较高分布于1-10ms区间孔喉的动用程度尤为重要.

英文摘要：

The water flooding experiment was carried out using nuclear magnetic resonance（NMR）high pressure displacement system in order to definite the occurrence state of residual oil and evaluate the factors affecting water displacement efficiency in ultra-low permeability sandstone.The results show that average water oil displacement efficiency of experimental sample is 35.79%,and the pore throats distributing 1-10ms and 10-100ms are not only the main distribution range of oil under the saturated oil condition but also the main occurrence space of residual oil.Producing effect of medium pore throat distributing 10~100 ms is the best,and which lead to the highest degree of contribution to oil displacement efficiency.The water displacement efficiency is influenced by physical properties,micro crack,pore throat heterogeneity and pore throat producing extent.The samples having uniform pore throat distribution could obtain better displacement effect even if the pore throat size is small.It is helpful to improve oil displacement efficiency through effective development of small pore throat firstly using the capillary imbibition effect,then improving the displacement speed to develop bigger pore throat.In order to improve the overall development for ultralow permeability sandstone,all scope of pore throat need to be effectively produced,so it is particularly important to improve small pore throat,especially high content of 1-10ms medium pore throat.