## 2 Geological Setting  
The Shuntuoguole Low Uplift (SLU) region, covering an exploration area of about 27,000 km\({}^{2}\), is located in the northern part of the Tarim Basin [26]. Situated between the two major uplifts of Tabei and Tazhong and the two major depressions of Awati and Manjiaer, the SLU region is the most important tectonic nexus of the Tarim Basin (Figure 1a). The SLU may have experienced at least four tectonic evolutionary stages, as follows [1; 27]: (1) the Cambrian-Middle Ordovician marginal aulacogen and weak extensional craton stage; (2) the Middle Ordovician-Middle Devonian craton uplift formation evolution and intense compression stage; (3) the Early Permian-Jurassic continuous uplift and compression stage; (4) the Jurassic-Neogene adjustment and reshaping stage. The SLU region experienced a complex multiphase sedimentary-tectonic evolution process, providing good geological conditions for the development of multistage reservoirs and the formation and accumulation of hydrocarbons. Stratigraphically, the SLU region has been in a relatively stable subsidence burial area for a long time, and the Upper Paleozoic and Neogene strata were formed later [14]. As shown in Figure 1b, the Lower Paleozoic Cambrian strata are relatively intact, including the Yuertusi formation (\(\mathbb{C}\)1 ny), Xiaoerbulake formation (\(\mathbb{C}\)1x), Wusongerge formation (\(\mathbb{C}\)1w), Shayilike formation (\(\mathbb{C}\)2s), Awatage formation (\(\mathbb{C}\)2a) and the Lower Quilitage formation (\(\mathbb{C}\)3q), from bottom to top. The Ordovician strata are composed of the Penglaiba formation (\(\mathbb{O}\)1p), Yingshan formation (\(\mathbb{O}\)1-2y), Yijianfang formation (\(\mathbb{O}\)2 yj), Tumuxiuke formation (\(\mathbb{O}\)3t), Lianglitage formation (\(\mathbb{O}\)3l), and Sangtamu formation (\(\mathbb{O}\)3s), from bottom to top (Figure 1b). At present, the main targets for the exploration and de velopment of SLU are carbonate rocks in the Ordovician strata of O\({}_{1\text{-}2}\)y and O\({}_{2}\)y\({}_{\text{j}}\), the main hydrocarbon source rock is the Lower Cambrian Yuertusi formation (\(\text{C}_{1}\)y), and the Upper Ordovician Sangtamu formation (O\({}_{3}\)s) develops regional giant thick-layer mudstone with favorable capping conditions, which together comprise an essential source-reservoir-caprock association [14; 28; 29; 30; 31].  
The Shunbei No. 1 Fault zone (the F1 zone), a northeast-oriented regulatory strike-slip fault between the Taibei Uplift and the Tazhong Uplift (Figure 1b), is located in the northeastern part of SLU and cuts through the north-northeast-oriented faults, indicating its late-phase continuous activity [14]. Recently, volatile light hydrocarbons have been discovered along the SBI in the carbonate reservoirs of the Yijianfang (O\({}_{2}\)yj) and Yingshan (O\({}_{1\text{-}2}\)y) formations at burial depths of more than 7300 m [13]. The existing reservoir temperature ranges from 154.80 \({}^{\circ}\)C to 172.40 \({}^{\circ}\)C, with estimated geothermal gradients ranging from 2.04 \({}^{\circ}\)C/100 m to 2.23 \({}^{\circ}\)C/100 m. The reservoir pressure ranges from 83 MPa  
Figure 1: (**a**) Regional location and tectonic map of the Shunbei region of the Tarim Basin, China. (**b**) Distribution map of the studied oil samples located near the Shunbei No. 1 fracture zone (left) and stratigraphic distribution map of the study area (right) (after [PERSON] et al. [17]).  
to 88 MPa, with a pressure coefficient of 1.09-1.16, forming a normal-pressure unsaturated volatile reservoir [32].