湖相页岩油可动性——以渤海湾盆地济阳坳陷东营凹陷为例

Movability of lacustrine shale oil: A case study of Dongying Sag, Jiyang Depression, Bohai Bay Basin

以渤海湾盆地济阳坳陷东营凹陷古近系沙河街组湖湘页岩为例,通过采集不同埋深页岩岩心样品,采用实验分析与测井资料相结合的研究方法,系统研究沙三下亚段（Es3^x）和沙四上亚段（Es4^s）页岩孔隙度、压缩系数、岩石力学性质、含油饱和度、气油比及原油饱和压力等特征,在此基础上,从地层能量角度,分析页岩油的可动性。研究表明,Es4^s和Es3^x弹性可动油率和溶解气驱动可动油率均随深度增加而增大,Es4^s页岩弹性可动油率和溶解气驱动可动油率均高于Es3^x页岩。2800-4000m深度范围内,Es3^x总可动油率为8%-28%,Es4^s为9%-30%。综合页岩含油饱和度变化剖面和可动油率变化剖面,认为3400m以深是东营凹陷Es3^x和Es4^s页岩油勘探开发的有利区。

Taking the Paleogene Shahejie Formation lacustrine shale in Dongying Sag, Jiyang Depression, Bohai Bay Basin, as an example, this paper makes a systematic study on the properties of shale of lower part of Sha-3 Member（Es3^x） and upper part of Sha-4 Member（Es4^s）, including porosity, compressibility, mechanical properties, oil saturation, gas-oil ratio and oil saturation pressure by lab analysis and well log data of shale cores taken from different depths. On this basis, the movability of shale oil is discussed in terms of formation energy. According to the study results, both the elastic movable oil ratios and the solution gas driving movable oil ratios of Es3 xand Es4^s increase with the shale burial depth, and both ratios of Es4 s are generally higher than that of Es3^x at the same depth. Within the depth of 2800 – 4000 m, the total movable oil ratio of Es3^x varies from 8% to 28%, while the total movable oil ratio of Es4 s varies from 9% to 30%. Combining with the profiles of oil saturation and movable oil ratio of shale, a conclusion is made that the shale of Es3 x and Es4 s deeper than 3 400 m in the study area are favorable objects for shale oil exploration.