羌塘盆地侏罗系曲色组油苗有机地球化学特征及意义

Organic geochemistry and significance of oil seepages in the Quse Formation in the Qiangtang Basin

关键词:  羌塘盆地  曲色组  油苗  有机地球化学特征

Key words:  Qiangtang Basin  Quse Formation  oil seepages  organic geochemical characteristics

摘要:

针对QK-3井取得的曲色组泥页岩、油页岩以及液态油苗进行了有机地球化学特征分析，探讨曲色组烃源岩与液态油苗的亲缘性。研究表明：QK-3井曲色组泥岩及油页岩达一般—好烃源岩标准，有机质类型多为Ⅰ及Ⅱ₁型，处于成熟阶段；油页岩、油苗样品生物标志物对比表明，二者形成环境及成熟度特征较为接近，具有很好的可比性，在曲色组中发现的油苗与该组烃源岩有着较好的亲缘关系，油苗源于曲色组油页岩等烃源岩。综合烃源岩有机地球化学特征及曲色组分布范围与沉积厚度认为，下侏罗统曲色组泥质烃源岩的生烃能力属于较好级别，是研究区内最主要的烃源岩，具有较好的勘探潜力。

Abstract:

In this paper, samples from Quse Formation mudstone, oil shale and liquid oil seedlings obtained from well QK-3 have been analyzed and their organic geochemical characteristics and the relationship between source rocks and liquid oil seedlings have been discussed. The results show that the mudstone and oil shale of QK-3 hole have reached the standard of medium to good source rocks, most of which are Ⅰtype or Ⅱ₁ type and are in the mature stage. The comparison of biomarkers shows that both the oil shale and oil seepages samples are with similar formation environment and maturity characteristics. The oil seepages found in Quse Formation have a good genetic relationship with the source rock, indicating that the oil seepages are derived from the oil shale of Quse Formation. Based on the organic geochemical characteristics of the source rocks, the distribution range, and the sedimentary thickness of Quse Formation, it is considered that the argillaceous source rocks of the lower Jurassic Quse Formation are of good hydrocarbon generation capacity. It is the most important source rock with the potential to form natural gas hydrate in study area.