Petroleum geochemistry and origin of shallow-buried saline lacustrine oils in the slope zone of the Mahu sag, Junggar Basin, NW China

• DOI: 10.1016/j.petsci.2023.08.024
• Publication Date: 2023-08-22T06:32:48Z
• Authors: Dong-Yong Wang; Mei-Jun Li; Yang Zhou; Lu Yang; Yuan-Feng Yang; Er-Ting Li; Jun Jin; Xian-Li Zou; Bo-Dong Xu
• Keywords: Terrigenous sediment; Paleogene

Recently, significant oil discoveries have been made in the shallower pay zones of Jurassic Badaowan Formation (J1b) Mahu Sag, Junggar Basin, Northwest China. However, little work has done on geochemical characteristics and origins J1b reservoir. This study analyzes 44 14 source rock samples from area order to reveal their organic oils. The oils are characterized by a low Pr/Ph ratio high β-carotene gammacerane indices, which indicate that they were mainly generated rocks deposited hypersaline environment. also extremely enhanced C29 regular steranes, possibly derived halophilic algae. Oil-source correlation shows Lower Permian Fengcheng (P1f) rocks, strongly stratified highly saline water column with predominance algal/bacterial input matter. Middle lower-Wuerhe (P2w), fresh slightly conditions greater terrigenous matter, make only minor contribution reconstruction accumulation process reservoir may twice charged during Late Jurassic–Early Cretaceous Paleogene–Neogene, respectively. A large amount volume hydrocarbons P1f leaked T1b reservoirs migrated along faults connecting beds shallow-buried secondary into traps, resulting large-scale accumulations J1b. These results crucial for understanding petroleum system Sag will provide valuable guidance exploration formations slope sag.