基于核磁共振驱替技术的页岩含油性评价

Evaluation of shale oil based on NMR displacement technology

为评价页岩含油性,利用核磁共振技术,对页岩样品进行核磁共振油驱水测试并分析样品在不同驱替时间下的T_2谱特征。结果表明,在毛细管力作用下,小孔喉和较小孔喉在整个驱替过程中含油量一直缓慢增长,因此较小孔喉和小孔喉是页岩油气成藏过程中原油的主要赋存场所。页岩含油性与物性参数之间没有表现出明显的相关关系。影响页岩含油性的主要因素是孔隙结构,不同的孔隙结构对应不同的驱替机理和驱替通道。此外,微裂缝的存在改变了页岩微观驱替机理,导致驱替波及程度变小,含油饱和度降低。

In order to evaluate the oil content of shale,NMR displacement technology was used to test shale samples and the T2 spectrum characteristics of samples under different displacement time was analysed.The result shows that the oil content of small pore and smaller pore is increasing slowly in the whole displacement process because of the capillary force.Therefore, the smaller pore and small pore are the main place of oil storage.There is no significant correlation between oil content and physical property of shale.Pore structure is the main factor which influences oil content of shale.Different pore structure correspond to different displacement mechanism and displacement channel.In addition, microcracks change the displacement mechanism of shale,resulting in smaller sweep area and lower oil saturation.