Abstract:

To supplement the database of petroleum resources in the eastern Qinghai-Tibet Plateau and establish a solid scientific basis for the exploitation and utilization of oilshale resources in the Nangqian basin, investigations were conducted on the industrial quality and biomarker compounds of oil shale in the study area. This paper selects a total of 11 samples from four outcrops in the Nangqian basin and investigates the industrial quality, pyrolytic product composition, and organic matter evolution characteristics of the oil shale through methods such as rock pyrolysis-mass spectrometry, dry distillation-component analysis, and industrial quality analysis. The results indicate that the Nangqian oil shale exhibits high ash content (average 72.18%), low oil content (average 3.78%), and low sulfur (average 1.11%) characteristics. The pyrolytic products are mainly composed of low carbon number saturated hydrocarbons (C7-C35) and aromatics, with a Pr/Ph ratio less than 1 and a distribution characteristic of triaromatic hydrocarbons, indicating that it formed in a deep-water, high-salinity, strongly reducing lacustrine environment. The maturity parameter of aromatics corresponds to a transformation Ro range (0.58%-0.94%), suggesting that it is in the low-mature-mature stage; the distribution characteristic of n-alkanes reflects that the organic matter is mainly derived from lower aquatic organisms.

Key words: Nangqian basin, Paleogene, oil shale, biomarker compounds, industrial quality