## 1 Introduction  
With the continuous advancement of hydrocarbon exploration, the exploration of ultra-deep hydrocarbon deposits (burial depths over 6000 m) has received increasingly great attention [1, 2, 3]. In recent years, large-sized ultra-deep reservoirs have been discovered in the Tarim Basin, Sichuan Basin, and Bohai Bay Basin, gradually becoming an important replacement area for the exploration and development of oil and gas in China [4, 5, 6, 7]. Currently, ultra-deep light oil and condensate reservoirs have been discovered in the Shunbei field (burial depths greater than 7300 m) in the northern part of the Shuntuoguole area, which has become a new successive area for exploration in the Tarim Basin after Tabei and Tazhong, demonstrating favorable exploration prospects for ultra-deep reservoirs [8; 9; 10]. Obviously, the discovery of ultra-deep light oil reservoirs, especially the deepest well in Asia, the Luntan1 well (LT1), has broken the traditional perceptions of the petroleum accumulation mechanism; low geothermal gradient and rapid subsidence after petroleum accumulation jointly contribute to the preservation of liquid petroleum in ultra-deep strata in the Tarim Basin, which extends the range of the \"oil window\" [9; 11; 12]. However, the diversity and complexity of the hydrocarbon's origins, coupled with the heterogeneity of ultra-deep organic matter and the complexity of diagenesis, make it more difficult to shed light on the ultra-deep hydrocarbon accumulation mechanism.  
Recently, the discovery of volatile oils in conjunction with commercial oil flows along the Shunbei 1 fracture zone (F1) in the northern part of the SLU area reveals that the area has great potential for ultra-deep petroleum exploration [13; 14]. Despite extensive studies [9; 15; 16; 17; 18; 19; 20; 21; 22; 23] on the hydrocarbon accumulation characteristics of the F1 zone, the origin of these ultra-deep Ordovician hydrocarbons is still hotly disputed. Previous studies have offered three main opinions on the origin of the Ordovician hydrocarbons in the region: (1) Cambrian-Lower Ordovician source rocks (\(\mathbb{C}\)-O\({}_{1}\)) [20; 24]; (2) Cambrian source rocks [18; 25], especially the Lower Cambrian Yuertusi formation (\(\mathbb{C}\)1y) source rocks; (3) the adjustment of the deeper petroleum aggregated in the Cambrian carbonate reservoirs [17]. However, there are many factors affecting the difficulty in identifying the origin of ultra-deep petroleum, such as the limited source rocks, the failure of numerous biomarkers due to the high maturity, the complexity of petroleum geochemical characteristics due to multi-phase charging, and the influence of secondary alterations. Therefore, in order to allow for a more comprehensive understanding of the hydrocarbon origin of the F1 zone, the geochemical correlation of oil and gas in this area still merits further investigation. In this study, crude oils and natural gases from the F1 zone are investigated to evaluate their thermal maturity, depositional environment, and biogenic hydrocarbon parent materials, the extent of secondary alterations, source rocks, and possible migration directions, based on the analysis of molecular compositions and stable carbon isotopes of crude oils, combined with the compositions and component carbon isotopes of natural gases. This will contribute to further insights into the accumulation mechanism of ultra-deep hydrocarbons in the study area and provide theoretical guidance for hydrocarbon exploration deployment in the region.