Geologic characteristics of hydrocarbon-bearing marine, transitional and lacustrine shales in China. (1st January 2016)

• Record Type: Journal Article
• Authors: Jiang, Shu; Xu, Zhengyu; Feng, Youliang; Zhang, Jinchuan; Cai, Dongsheng; Chen, Lei; Wu, Yue; Zhou, Dongsheng; Bao, Shujing; Long, Shengxiang
• Is Part Of: Journal of Asian earth sciences. Volume 115(2016)
• Page Start: 404
• Page End: 418
• Publication Date: 2016-01-01
• Subjects: Marine shale -- Lacustrine shale -- Transitional shale -- Geochemistry -- Mineralogy -- Tectonic disruption; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2015.10.016
• Languages: English
• ISSNs: 1367-9120

Abstract

Highlights: Unique geology of Pre-Cambrian to Cenozoic hydrocarbon-bearing marine, transitional and lacustrine shales in China is summarized. Robust comparisons between marine, lacustrine and transitional shales are revealed based on the geochemical, mineralogical, petrophysics, petrology tests and heterogeneity analysis. Depositional model for lacustrine and marine shales in China is proposed to predict shale reservoir. The tectonically stable areas are suggested for exploration of shale gas and shale oil in China. Abstract: Organic-rich shales spanning in age from Pre-Cambrian to Quaternary were widely deposited in China. This paper elaborates the geology and unique characteristics of emerging and potential hydrocarbon-bearing shales in China. The Pre-Cambrian Sinian Doushantuo to Silurian black marine shales in the intra-shelf low to slope environments were accumulated in South China and Tarim Platform in Northwest China. These marine shales with maturity (Ro) of 1.3–5% are in dry gas window. During Carboniferous to Permian, the shales associated with coal and sandstones were mainly deposited in coastal swamp transitional setting in north China, NE China, NW China and Yangtze platform in South China. These transitional shales are generally clay rich and are potential gas-bearing reservoirs. Since Middle Permian, the lacustrine shales with total carbon content (TOC) up to 30% and Ro mainly in oil window are widely distributed in all the producing basins in China. The lacustrine shales usually have more clay mineral content than marine shales and are characterized by rapid facies change and are interbedded with carbonates and sandstone. The high quality shale reservoir with high TOC, hydrocarbon content and brittle minerals content is usually located at transgressive systems tract (TST) to early highstand systems tract (EHST) interval deposited in anoxic depositional setting. Recent commercial shale gas production from the Silurian Longmaxi marine shale in the southeastern Sichuan Basin, preliminary tight oil production associated with lacustrine hydrocarbon-bearing shale intervals and hydrocarbon shows from many other shales have proven the hydrocarbon-bearing shales in China are emerging and potential shale gas and tight (shale) oil plays. Tectonic movements could have breached the early hydrocarbon accumulation in shales and tectonically stable areas are suggested to be favorable prospects for China shale plays exploration and production.