Organic geochemical characteristics of the Carboniferous-Jurassic potential source rocks for natural gas hydrates in the Muli Depression, Southern Qilian Basin

被引：0
|
作者：
Fan D. [1 ,2 ]
Lu Z. [2 ]
Li G. [3 ]
Xiao R. [2 ]
机构：
[1] School of Energy Resources, China University of Geosciences (Beijing), Beijing
[2] Oil & Gas Survey Center, China Geological Survey, Beijing
[3] Wuxi Research Institute of Petroleum Geology, Petroleum Exploration and Production Research Institute, SINOPEC, Wuxi, 214151, Jiangsu
来源：
Lu, Zhenquan (luzhq@vip.sina.com) | 1600年 / Editorial Department of Oil and Gas Geology卷 / 41期
关键词：
Gas source rock; Muli Depression; Natural gas hydrate; Organic geochemistry; Southern Qilian Basin;
D O I：
10.11743/ogg20200211
中图分类号：
学科分类号：
摘要：
During the investigation of the basic geological profile of natural gas hydrates in the Muli Depression, Southern Qilian Basin, we analyzed the carbon-rich mudstone and mudstone sampled from 5 sections of the Carboniferous, Per-mian, Triassic and Jurassic sequences. The geochemical characteristics such as organic matter abundance, organic matter type and organic matter maturity of four sequences were accordingly studied in detail. The organic geochemical indexes of each sequence were analyzed and compared in order to explore the gas source rock qualities for different sequences of (gas) source rocks for natural gas hydrates. The results show that the Carboniferous-Permian organic matter abundance is relatively low, the TOC (total organic carbon) content is generally less than 0.4%, both of which indicate the source rocks are very lean. The kerogen are mainly over-matured TypesⅡ and Ⅲ organic matters, resulting in poor hydrocarbon generation capacity. Thus, the source rocks could not be the potential gas source rocks for natural gas hydrate generation. The samples collected from the Triassic strata have TOC value of generally greater than 1% and an average chloroform bitumen "A" of 0.89, which are mostly good and very good source rock samples, with a small number of samples with poor or non-hydrocarbon source rock quality. The organic materials are mainly matured Type Ⅲ as a whole with a small number of Type Ⅱ2, with a vitrinite reflectance (Ro) value of 0.74%-0.98%. These strata can be viewed as the main potential gas source rocks for natural gas hydrate generation. The Jurassic strata are dominated by source rocks of very good, good, and medium qualities with limited number of poor source rocks. Their organic materials are mainly matured Type Ⅱ and Ⅲ with a Ro value of 0.62%-0.97%, and thus can be regarded as the secondary potential gas source rocks for the generation of natural gas hydrates. © 2020, OIL & GAS GEOLOGY Editorial Board. All right reserved.
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页码：348 / 358
页数：10
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