Detection and significance of higher thiadiamondoids and diamondoidthiols in oil from the Zhongshen 1C well of the Tarim Basin, NW China
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Oil and gas breakthroughs have been achieved in the Zhongshen 1 (ZS1) and 1C (ZS1C) wells in Cambrian pre-salt from the Tarim Basin in northwest China. However, Middle and Lower Cambrian reservoirs reveal substantial differences in the geochemistry and secondary alteration characteristics between the oils collected from the two wells. High concentrations of thiadiamondoids and diamondoidthiols, including thiatetramantanes, tetramantanethiols, thiapentamantanes, and pentamantanethiols, are detected in the organic sulfur compound fraction of concentrated oil collected from the ZS1C well, which samples the Lower Cambrian Xiaoerbulake Formation. Higher diamondoids, such as tetramantanes, pentamantanes, hexamantanes, and cyclohexamantane, also occur in the saturate fractions of the concentrated ZS1C oil. The presence of these compounds is verified by mass spectra analysis and comparison with previous studies. During thermochemical sulfate reduction (TSR), the cage of higher diamondoids is interpreted to open because of sulfur radicals forming open-cage higher diamondoid-like thiols, followed by cyclization that leads to the formation of high thiadiamondoids. Using D16-adamantane as an internal standard, the concentrations of lower diamondoids and thiadiamondoids of non-concentrated Cambrian oil from well ZS1C are 83874 and 8578 μg/g, respectively, which are far higher than Cambrian oil from well ZS1 and most Ordovician oils in the Tarim Basin. The high concentrations of lower thiadiamondoids and occurrence of higher thiadiamondoids and diamondoidthiols support that the oil from well ZS1C is a product of severe TSR alteration.
KeywordsTarim Basin Cambrian Well Zhongshen 1C Higher thiadiamondoid Higher diamondoidthiol Higher diamondoid Thermochemical sulfate reduction (TSR)
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We appreciate the thoughtful and constructive comments of anonymous reviewers. This research was supported by the National Natural Science Foundation of China (Grant No. 41772153), State Key Laboratory of Organic Geochemistry, GIGCAS (Grant No. SKLOG- 2017-02), National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No. 2017ZX05005-002), and SINOPEC Ministry of Science and Technology (Grant No. P16090, P17049-1).
- Cai C, Amrani A, Worden R H, Xiao Q, Wang T, Gvirtzman Z, Li H, Said–Ahmad W, Jia L. 2016b. Sulfur isotopic compositions of individual organosulfur compounds and their genetic links in the Lower Paleozoic petroleum pools of the Tarim Basin, NW China. Geochim Cosmochim Acta, 182: 88–108CrossRefGoogle Scholar
- Dahl J E P, Moldowan J M, Peakman T M, Clardy J C, Lobkovsky E, Olmstead M M, May P W, Davis T J, Steeds J W, Peters K E, Pepper A, Ekuan A, Carlson R M K. 2003b. Isolation and structural proof of the large diamond molecule, cyclohexamantane (C26H30). Angew Chem Int Ed, 42: 2040–2044CrossRefGoogle Scholar
- Dahl J E, Moldowan J M, Koskella D L. 2017. Source identification of Permian basin oils using higher diamondoids. In: Proceedings of the 28th International Meeting on Organic Geochemistry IMOG 2017, Florence, Italy, 17–22 September. 268Google Scholar
- Ma A L, Jin Z J, Zhu C S. 2009. Quantitative analysis on absolute concentration of diamondoids in oils from Tahe oilfield (in Chinese). Acta Petrol Sin, 30:214–218Google Scholar
- Moldowan J M, Zinniker D, Moldowan S, Dahl J. 2013. Novel technologies for unraveling the charge history of multiply–sourced petroleum systems. In: AAPG Hedberg Research Conference, “Fundamental Controls on Petroleum Systems in Lower Paleozoic and Older Strata”, Beijing, China, April 21–24, 2013. http://www.searchanddiscovery. com/abstracts/html/2013/90175 hedberg/abstracts/mol.htmGoogle Scholar
- Petrov A., Arefjev O. A. and Yakubson Z. V. 1974. Hydrocarbons of adamantane series as indices of petroleum catagenesis process. In: Tissot B, Bienner F eds. Advances in Organic Geochemistry 1973. Paris: Editions Technip. 517–522Google Scholar
- Wang D W, Wang T G, Li M J, Song D F, Shi S B. 2016. The distribution of chrysene and methylchrysenes in oils from wells ZS5 and ZS1 in the Tazhong Uplift and its implications in oil–to–source correlation (in Chinese). Geochimica, 45:451–461Google Scholar
- Wang G L, Li N X, Gao B, Li X Q, Shi S B, Wang T G. 2013. Thermochemical sulfate reduction in fossil Ordovician deposits of the Majiang area: Evidence from a molecular marker investigation. Chin Sci Bull, 58:3450–3457Google Scholar
- Wang Z M, Xie H W, Chen Y Q, Qi YM, Zhang K. 2014. Discovery and exploration of Cambrian subsalt dolomite original hydrocarbon reservoir at Zhongshen–1 well in Tarim Basin (in Chinese). China Petrol Expl, 19: 1–13Google Scholar
- Wei Z. 2006b. Molecular organic geochemistry of cage compounds and biomarkers in the geosphere: a novel approach to understand petroleum evolution and alteration. Doctoral Dissertation. California: Stanford University. 275–375Google Scholar
- Wei Z, Moldowan J M, Peters K E, et al. 2007a. The abundance and distribution of diamondoids in biodegraded oils from the San Joaquin Valley: implications for biodegradation of diamondoids in petroleum reservoirs. Org Geochem, 38: 854–863Google Scholar
- Zhang S, Huang H, Su J, Liu M, Wang X, Hu J. 2015b. Geochemistry of Paleozoic marine petroleum from the Tarim Basin, NW China: Part 5. Effect of maturation, TSR and mixing on the occurrence and distribution of alkyldibenzothiophenes. Org Geochem, 86: 5–18Google Scholar
- Zhu X J, Chen J F, He L W, Wang Y F, Zhang W, Zhang B S, Zhang K. 2017. Geochemical characteristics and source correlation of hydrocarbons in the Well Luosi 2 of Maigaiti Slope, Tarim Basin, China (in Chinese). Nat Gas Geosci, 28: 566–574Google Scholar