Differential Accumulation Patterns of Mesozoic Hydrocarbon Reservoirs in the Northern Monocline Belt of the Kuqa Depression (Tarim Basin, NW China): Constraints from Basin Modeling and PVTx Simulation

The northern monocline belt of the Kuqa Depression, Tarim Basin, is characterized by structural complexity and limited exploration, despite its considerable hydrocarbon potential. This study subdivides the area into the Kubei and Bashi segments, separated by the Heiyingshan strike-slip fault, and investigates their differentiated hydrocarbon accumulation patterns using integrated geochemical fingerprinting, Bayesian classification, hierarchical clustering, fluid inclusion analysis, PVTx modeling, burial–thermal history reconstruction, and seismic interpretation. The results show that the Kubei segment, controlled by multi-phase thrusting, follows a “continuous hydrocarbon generation–episodic charging” model. Oil–source correlation indicates that hydrocarbons were mainly derived from the Triassic Huangshanjie Formation (T 3 h), with minor input from the Karamay Formation (T 2–3 k). Three types of hydrocarbon-bearing inclusions in well MQ1 record three charging events at approximately 55 Ma, 23 Ma, and 3 Ma. In contrast, the Bashi segment is mainly controlled by strike-slip faulting and exhibits a “late rapid burial–two-phase charging” model. Hydrocarbons in the Bashi segment are primarily sourced from T 2–3 k source rocks. Fluid inclusions in well KQ1 indicate two charging stages during the early stage of Kangcun Formation deposition and during Kuche Formation deposition, at approximately 5.3 Ma and 3 Ma. These results reveal a segmented petroleum system controlled by contrasting tectonic histories and source rock contributions, providing important guidance for future deep hydrocarbon exploration in the northern Kuqa Depression.