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Gas generation period and quantity of organic-rich Niutitang Shale in Qiannan Depression, China |
CHEN Fangwen1, LU Shuangfang1, DING Xue2
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(1.Institute of Unconventional Hydrocarbon and New Energy Sources in China University of Petroleum, Qingdao 266580, China;2.College of Chemical Engineering in China University of Petroleum, Qingdao 266580, China)
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Abstract: |
In order to evaluate the gas generation period and quantity of the organic-rich Niutitang Shale in Qiannan Depression, pyrolysis experiments were performed using the samples of Xiamaling Shale from the Upper Proterozoic Qingbaikou system in the North China Platform, and the crude oil generated from the Lower Cambrian source rocks in Tarim Basin. Combining the sedimentary and thermal history of the study area, the gas generation period and quantity were calculated using the chemical kinetic method. The results show that the oil generation period of Niutitang Shale is about 510-430 Ma in Qiannan Depression, i.e., from the early stage of Early Ordovician to the end of Early Ordovician. The gas generation period of Niutitang Shale is about 500-240 Ma, from the Early Ordovician to the Late Permian, including two stages that are gas generation from kerogen (500-475 Ma) and gas generation from oil cracking (400-240 Ma), from the Early Ordovician to the Middle Ordovician and from the Devonian to the Early Permian, respectively. The total gas generation quantity of the organic-rich shale from Niutitang Shale in Qiannan Depression is about 2735.7×1011m3. The main gas generation periods are Ordovician, Devonian and Carboniferous. Accordingly, the gas generation quantity is 14.72 m3/t, 8.87 m3/t and 6.54 m3/t, respectively, which is 41.0%, 24.7% and 18.0% in the total gas generation quantity from unit weight shale, respectively. |
Key words: Qiannan Depression Niutitang Shale organic-rich shale gas generation period gas generation quantity |
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