Geochemistry of petroleum systems in the eastern Pearl River Mouth Basin: evidence for mixed oils

Reconstruction of the Cenozoic History of Hydrocarbon Fluids from Rifting Stage to Passive Continental Margin Stage in the Huizhou Sag, the Pearl River Mouth Basin

“…The modeling results indicate that hydrocarbon generation potential of the Wenchang Fm in the Huixi half-graben is much higher than that in the Huibei halfgraben, with oil generation potential of 70 mg/g⋅TOC and gas generation potential of around 150 mg/g⋅TOC. Hydrocarbon expulsion of the Wenchang Fm began at 33.9 Ma and was Wenchang dark mudstone and shoreline-shallow lacustrine Enping dark mudstone and accumulated via lateral migration from the deeply buried source rocks in the HZS [2,3,43,44,47]. The modeling results indicate that oil expulsion in the HZS is mainly from the Eocene Wenchang source rocks and occurred during postrift stage.…”

“…The ratio of pristane (Pr) and phytane (Ph) value is 6.35 in the Wenchang source rocks from well 243 with low content of 4-methyl sterane (Figure 10), which means that the source rocks were formed in a shallow water environment. The ratio of Pr/Ph value is 2.70 in the Wenchang source rocks from well 132 with high content of 4-methyl sterane, which indicates that the source rock is originated from lacustrine with algal input ( [43,44], Fu and Zhu, 2007). The ratio of Pr/Ph values is more than 6 in the Enping source rocks.…”

“…The ratio of Pr/Ph values is more than 6 in the Enping source rocks. The 4-methyl sterane content is low and the content of C 29 sterane is relatively higher than the levels of C 27 sterane and C 28 sterane (Figure 10), which indicates that the Enping Fm developed in the environment containing both algal and land plant material ( [43,44], Fu and Zhu 2007).…”

“…(Figure 2). During the Paleogene continental rift stage, the Zhu-Qiong I (49.0 Ma) and Zhu-Qiong II Movement (38.0 Ma) not only formed the structural configuration of the HZS [43,44,57] but also developed regional unconformities ( Figure 13(f)). In the early Oligocene, the Nanhai Movement (33. to steady thermal subsidence ( Figure 13(e)).…”

Tracing early-charged oils and exploration directions for the Wenchang A sag, western Pearl River Mouth Basin, offshore South China Sea

“…C 30 4-methylsteranes derived from certain dinoflagellates thriving in freshwater lakes (Goodwin et al, 1988), could reflect the input of aquatic organic matter (Peters et al, 2005). All of these biomarker indices have been extensively applied in studies of the Pearl River Mouth Basin (Huang et al, 2003;Zhang et al, 2003;Gong and Li, 2004).…”