Cycles of fine-grained sedimentation and their influences on organic matter distribution in the second member of Paleogene Kongdian Formation in Cangdong Sag, Bohai Bay Basin, East China

Zhao, Xianzheng; Pu, Xipeng; Yan, Jiayong; Jin, Fu; Shi, Zheming; Chai, Gongquan; Han, Wenzhong; Liu, Yan; Jiang, Wenya; CHEN, Changwei; Zhang, Wei; Zheng, Fang; Xie, Delu

doi:10.1016/s1876-3804(23)60408-2

Cited by 4 publications

(2 citation statements)

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“…Ek 2 is a complete sequence that is divided into four parasequences from bottom to top: Ek 2 4 , Ek 2 3 , Ek 2 2 , and Ek 2 1 [38,39]. The Ek 2 4 member is the fine sandstone and siltstone deposited in the delta sedimentary environment, while Ek 2 3 -Ek 2 1 represent the fine-grained sedimentary segment in a semi-deep lake to deep lake environment [35]. This study focuses on the fine-grained sedimentary segment (Ek 2 3 -Ek 2 1 ) located in the Guandong region, which is in the eastern part of the Cangdong Sag.…”

Section: Geological Settingmentioning

confidence: 99%

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Lithofacies Characteristics and Sweet Spot Distribution of Lacustrine Shale Oil Reservoirs: A Case Study of the Second Member of the Kongdian Formation in the Cangdong Sag, Bohai Bay Basin

Zhan,

Lin,

et al. 2023

Minerals

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In contrast to marine shale oil reservoirs, lacustrine shale exhibits rapid lithofacies changes and strong mineral compositional heterogeneity, posing new challenges for the evaluation and distribution prediction of shale oil sweet spots. The oiliness, reservoir properties, oil fluidity, and fracability of different lithofacies were analyzed using emission-scanning electron microscopy (FE-SEM) observation, low-pressure nitrogen physisorption (LNP) analysis, mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and triaxial compression testing. Based on the mineral composition obtained from X-ray diffraction (XRD) analysis, total organic carbon (TOC) content, and sedimentary structure, four lithofacies were classified, which are organic-rich laminated calcareous shale (LC), organic-rich laminated siliceous shale (LS), organic-rich laminated mixed shale (LM), and organic-poor massive calcareous shale (MC). Considering the factors of oiliness, reservoir properties, oil fluidity, and fracability, the LC and LS lithofacies were determined as being high-quality sweet spots (type I). Within the stratigraphic sequence divided by GR-INPEFA curves, multi-resolution graph-based clustering (MRGC) analysis of sensitive well logs was used to classify the lithofacies, after which the distribution of sweet spots was predicted. The results reveal that the sweet spots exhibit regular changes in their vertical distribution and a ring-like pattern in their planar distribution, influenced by variations in the sedimentary environment. This finding can offer valuable guidance for the future exploitation of shale oil in the Guandong region.

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Section: Geological Settingmentioning

confidence: 99%

“…(a) Location of the Cangdong Sag in Bohai Bay Basin (modified after[34]). (b) Structural and sedimentary facies map of the regional setting of the Cangdong Sag (modified after[35]). (c) Typical sedimentary strata section of the Cangdong Sag (modified after[36,37]).…”

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confidence: 99%