Organic geochemical characteristics of the upper Triassic source rocks in the Eastern Ordos Basin,China

Abstract

In this paper, the organic geochemical characteristics of the upper Triassic Yanchang Formation source rocks in the Panlong oilfield in the eastern Ordos Basin of China were systematically studied. The results showed that the organic matter abundance of the dark mudstone source rocks of the Chang 7 segment is high and reaches the standard of good or best source rocks. The organic matter type of the Chang 7 segment source rocks is mainly Type II₁ with strong oil generation ability. The biomarker compounds studies showed that the Chang 7 segment source rock has reached the mature stage, reflecting its good organic matter type and high evolution degree. The salinity of the original sedimentary water of this source rock is low, reflecting a terrestrial sedimentary environment. The oil source comparison confirmed that the crude oil Yanchang Formation in the Panlong oilfield was contributed by the Chang 7 source rocks.