A method for evaluating the thermal maturity of marine shale based on graptolite reflectance and Raman spectroscopy：A case from the Lower Palaeozoic Wufeng‒Longmaxi Formations，southern Sichuan Basin，SW China

被引：0
|
作者：
Meng J. [1 ,2 ]
Lyu P. [1 ,2 ]
Wu W. [3 ]
Pan R. [1 ,2 ]
Zhu Y. [3 ]
机构：
[1] Hubei Cooperative Innovation Center of Unconventional Oil and Gas, Yangtze University, Hubei, Wuhan
[2] Ministry of Education Key Laboratory of Oil and Gas Resources and Exploration Technology, Yangtze University, Hubei, Wuhan
[3] Shale Gas Research Institute of Southwest Oil & Gasfield Company, PetroChina, Sichuan, Chengdu
来源：
Oil and Gas Geology | 2022年 / 43卷 / 06期
关键词：
graptolite; Lower Palaeozoic; marine shale; Raman spectroscopy; Sichuan Basin; solid bitumen; thermal maturity; Wufeng ‒ Longmaxi Formations;
D O I：
10.11743/ogg20220620
中图分类号：
学科分类号：
摘要：
The marine shale of Wufeng-Longmaxi Formations is one of the main targets of the Lower Palaeozoic shale gas exploration in southern Sichuan Basin. The thermal maturity is a vital indicator for source rock and shale gas evaluation. Due to the lack of vitrinite，it has been difficult to establish a method to accurately evaluate the thermal maturity of Lower Palaeozoic marine shale. In total，33 core samples were selected from the Wufeng-Longmaxi Formations in southern Sichuan Basin to observe the optical characteristics of solid bitumen and graptolites and measure random reflectance. Simultaneously，Raman spectroscopic parameters of kerogen were also used to quantitatively analyze the change of thermal maturity. The results show that compared with solid bitumen，non-granular graptolites are more suitable for reflectance measuring because they have a single source，larger particle size and obvious characteristics，and the random reflectance（GRor）values of non-granular graptolites on sections perpendicular to bedding are more concentrated. The characteristics of Raman spectroscopic parameters of kerogen show that the relationship between GRor and the equivalent vitrinite reflectance （EqRo） is not a single linear relationship in the whole process of thermal evolution. By using Raman spectroscopic parameters of kerogen as mediators，a method for calculating EqRo by GRor was established. The calculation results show that the maturity of Wufeng-Longmaxi Formations in Changning，Luzhou-Dazu and Weiyuan areas decreases successively，their EqRo falls in the range of 2. 99 %-3. 91 %，2. 87 %-3. 54 % and 2. 46 % -3. 03 % ，and the average EqRo is 3. 44 % ，3. 22 % and 2. 77 % respectively. There is an abnormally high maturity area in the western Changning that calls for evaluation of its impact on shale gas exploration. © 2022 Editorial Department of Oil and Gas Geology. All rights reserved.
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页码：1515 / 1528
页数：13
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共 51 条
  • [1] Liang Digang, Guo Tonglou, Chen Jianping, Et al., Some progresses on studies of hydrocarbon generation and accumulation in marine sedimentary regions，southern China（Part 1）：Distribution of four suits of regional marine source rocks［J］, Marine Origin Petroleum Geology, 13, 2, pp. 1-16, (2008)
  • [2] Zhong Ningning, Zhao Zhe, Li Yanxia, Et al., An approach to the main controls on the potential of efficient hydrocarbon supply of marine sequences in South China［J］, Acta Geological Sinica, 84, 2, pp. 149-158, (2010)
  • [3] Zou Caineng, Dong Dazhong, Wang Shejiao, Et al., Geological characteristics，formation mechanism and resource potential of shale gas in China［J］, Petroleum Exploration and Development, 37, 6, pp. 641-653, (2010)
  • [4] Dong Dazhong, Cheng Keming, Wang Yuman, Et al., Forming conditions and characteristics of shale gas in the Lower Paleozoic of the Upper Yangtze region，China［J］, Oil & Gas Geology, 31, 3, pp. 288-299, (2010)
  • [5] Zhijun Jin, Hu Zongquan, Gao Bo, Et al., Controlling factors on the enrichment and high productivity of shale gas in the Wufeng-Longmaxi Formations，southeastern Sichuan Basin［J］, Earth Science Frontiers, 23, 1, pp. 1-10, (2016)
  • [6] Chen X，, Rong J，, Mitchell C E，, Et al., Late Ordovician to earliest Silurian graptolite and brachiopod biozonation from the Yangtze region，South China，with a global correlation［J］, Geological Magazine, 137, 6, pp. 623-650, (2000)
  • [7] Luning S，, Craig J，, Loydell D K，, Et al., Lower Silurian‘hot shales’in North Africa and Arabia：regional distribution and depositional model［J］, Earth-Science Reviews, 49, 1, pp. 121-200, (2000)
  • [8] Hao F，, Zou H，, Lu Y., Mechanisms of shale gas storage：Implications for shale gas exploration in China［J］, AAPG Bulletin, 97, 8, pp. 1325-1346, (2013)
  • [9] Xu Shuhui, He Sheng, Zhu Gangtian, Et al., Characteristics of saturated hydrocarbons from Lower Paleozoic marine shales in western Hubei-eastern Chongqing area and their indications［J］, Oil & Gas Geology, 39, 2, pp. 217-228, (2018)
  • [10] Yang Xiya, Liu Chenglin, Liu Wenpin, Et al., Characteristics of and factors influencing organic pores in the Lower Silurian Longmaxi Formation，Fushun-Yongchuan area，Sichuan Basin［J］, Oil & Gas Geology, 42, 6, pp. 1321-1333, (2021)
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