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Площадь: 185055.9 км²
Pearl River Mouth Basin
The Pearl River Mouth Basin (PRMB) is an important petroliferous basin in the South China Sea (Zhu et al., 1999; Zhang et al., 2004; Quan et al., 2019). It is ∼800 km long, 100–300 km wide, and covers an area of ∼175,000 km2 (Fig. 1). The PRMB is a passive margin Cenozoic rifted sedimentary basin formed on preCenozoic basement consisting of granitic, metamorphic, and sedimentary rocks (Li and Rao, 1994). It is located in the region where the Eurasian, Pacific, and Australia-India plates meet and thus experienced a complicated tectonic and sedimentary evolution history (Shao et al., 2016; Tang et al., 2017).
Distribution of oil and gas fields in the Pearl River Mouth Basin
Fig. 1. Location map showing the hydrocarbon accumulations and sub-units of the Zhu III sub-basin (modified from Quan et al., 2015). Sampled boreholes (black circles) are marked. SBF—south boundary fault.
The Zhu III sub-basin, one of four sub-basins in the Pearl River Mouth Basin (PRMB), is an important petroleum-producing region located in the western PRMB (Zhu et al., 1999; Cheng et al., 2015; Fig. 1). Generally, the evolution of the Zhu III sub-basin can be divided into an early faulting (syn-rifting) stage and a later subsidence (post-rifting) stage. During the faulting stage (66–30 Ma), the decrease of the subduction rate of the Pacific plate resulted in the decrease of horizontal compressive stress, therefore forming a group of NE- and NNE-oriented normal faults and depressions (Northrup et al., 1995). Sediments deposited during this stage consist of coarse-grained fluvial and deltaic sediments (the Paleocene Shenhu Formation, E1s), fine-grained lacustrine sediments (the Eocene Wenchang Formation, E2w), and coarse-grained lacustrine and swamp sediments (the Oligocene Enping Formation, E3e). These sediments were deposited in independent grabens and half-grabens, forming the vertical “coarse-fine-coarse” cycle. The Himalayan movement took place ∼30 m.y. ago and initiated the expansion of the seafloor in the South China Sea (Sun et al., 2009). After the Himalayan movement, the Zhu III sub-basin entered the subsiding stage, seawater began to encroach into the southern margin, and marine sediment began to be deposited (Lüdmann et al., 2001). These separated grabens and half-grabens gradually coalesced to form one large basin and filled with several sets of strata, including the Oligocene Zhuhai (E3z) Formation, the Miocene Zhujiang (N1z), Hanjiang (N1h), Yuehai (N1y) formations, the Pliocene Wanshan (N2w) Formation, and the Quaternary Qionghai (Qq) Formation (Fig. 2).
Fig. 2. Generalized stratigraphy of the Pearl River Mouth Basin, South China Sea (modified from Quan et al., 2019). Possible source rocks and major reservoir intervals are marked. QH—Qionghai Formation; RPW depth—relative paleowater depth.
Petroleum exploration in the Zhu III sub-basin started from the 1980s and seven oil fields, two gas fields, and five oil- and gas-bearing structures were found in the following 30 years (Quan et al., 2015). Major source rocks are the E2w and the E3e, and major reservoir rocks are the E3z and the N1z (Zhu et al., 1999; Fig. 2). The E3z marine mudstone has no significant contribution to hydrocarbon accumulations in the Zhu III sub-basin as a consequence of its low thermal maturity (Quan et al., 2015). However, it contributes to the Zhu II sub-basin (Jiang, 2017). The E2w is mainly composed of type I and II kerogens, while the E3e and E3z are mainly composed of type III kerogen based on organic petrological and Rock-Eval analyses (Jiang, 2017; Quan et al., 2017). Oil-source rock correlation has been investigated in the Zhu III sub-basin (Huang et al., 2003; Li et al., 2008; Gan et al., 2009; Xiao et al., 2009; Cheng et al., 2015), but the study of source rock depositional environment is limited (Huang et al., 1996; Wu et al., 1999; Quan et al., 2017).
Hydrocarbon migration pathway from the Huizhou Sag to the Dongsha Uplift in the north depression, Pearl River Mouth Basin
Data source: Paleosalinity assessment and its influence on source rock deposition in the western Pearl River Mouth Basin, South China Sea. Yongbin Quan, Jianzhang Liu, Fang Hao, Zhongxian Cai, Yuhong Xie. 2019
Analysis of the orderly distribution of oil and gas fields in China based on the theory of co-control of source and heat. Zhang G.C., Jin Li, Lan Lei, Zhao Zhao. 2015
Следующий Бассейн: Subei - Yellow Sea