Abstract:

Oil sand formation of about 90m in thickness and a large number of crevasse filling bitumen were first discovered in Upper Jurassic in the Northwest Qaidam Basin.Characteristics of the extracts of the oil sands and bitumen show that they are similar to Jurassic oils of the Northeast Qaidam Basin and differ from Tertiary oils in the Northwest Qaidam.Geological surveying indicates that there are thick Lower-Middle Jurassic source rocks in the Northwest Qaidam Basin. Biomarkers and other natures of extracts of the Jurassic source rocks are similar to the oil sands and the crevasse filling bitumen.Correlation of the oil sands and the source rocks suggests that the oils in the sands were derived from the Jurassic source rocks.The discovery of the oil sand and crevasse filling bitumen presents important signifi-cance to petroleum exploration in the Qaidam and other Basins along the Altun Fault.

Key words: Qaidam basin, Jurassic, oil sand, bitumen, source rock, biomarkers, petroleum exploration

摘要：

最近在柴达木盆地西部阿尔金断裂南侧地面剖面上侏罗统地层中首次发现了厚约90m的油砂及大量裂缝沥青脉。通过对这些油砂和沥青的分析研究发现,它们与柴达木盆地西部第三系原油差别较大,与柴达木盆地东部侏罗系原油较相似但也有一定差异。野外地质调查发现柴达木盆地西北部发育大量侏罗系烃源岩,其生物标志物等特征与这些油砂和沥青相似,综合分析认为这些油砂和沥青脉可能来源于成熟的侏罗系源岩。这些油砂的发现对柴达木盆地西北部及阿尔金断裂沿线盆地的油气勘探具有重要意义。

关键词: 柴达木盆地, 侏罗系, 油砂, 沥青, 烃源岩, 生物标志物, 油气勘探