Mixed Oil Distribution and Source Rock Discrimination of the Napu Depression, Bohaibay Basin
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摘要: 南堡凹陷油气源尚不清晰.首次采用单体烃碳同位素、结合生物标志物对全凹陷范围的原油和烃源岩进行了精细地球化学研究.分析表明, 拾场次洼沙三段烃源岩(Ⅰ类)发育高丰度的4-甲基甾烷与硫芴系列、贫伽玛蜡烷, 单体烃碳同位素为"斜直线型", 相关原油分布于高柳深层; 南堡凹陷南部沙二+三段源岩(Ⅱ类)伽玛蜡烷较发育, 但4-甲基甾烷不太发育, 其他特征类似于Ⅰ类源岩, 相关原油发现于潜山; 南堡凹陷沙一段-东三段烃源岩(Ⅲ类)富含重排甾烷与孕甾烷系列, 单体烃碳同位素较轻且近"W"型, 相关原油主要分布于南堡4、5号构造带.发现南堡油田1、2号构造带、老爷庙、高柳中浅层原油具有界于Ⅱ、Ⅲ类源岩(及相关原油)间的同位素与生标特征, 系混源油, 定量预测出混源油中沙二+三段源岩的贡献最高达82%.本研究关于Es2+3系南堡凹陷重要的油气源的认识不同于以往研究, 为该区进一步油气勘探提供了重要依据.Abstract: The origin of the hydrocarbons in the Napu depression is still not clear. Compound specific carbon isotope of n-alkanes has been utilized, combined with biomarkers to carry out detail geochemical investigations for the oils and source rocks within the whole depression for the first time. The results show that the Tertiary Es3 rocks (type-Ⅰ) in the Shichang sub-depression are characterized by abundant 4-methyl steranes and dibenzothiophenes but low concentration of gammacerane with a "tilted linear" shape of compound specific carbon isotope distribution. The type-Ⅰ genetic related oil has been discovered in the Tertiary Es3 interval of Gaoshangpu and Liuzan oilfields. The Tertiary Es2+3 rock (type-Ⅱ) in the south Nanpu depression is featured by a relatively high content of gammacerane while little 4-methyl sterane contained, and it has a similar carbon isotope curve and dibenzothiophene concentration to that of the type-Ⅰ rock. The type-Ⅱ genetic oil has been discovered in the Ordovician burial hills. The Tertiary Es1-Ed3 rock (Ⅲ) in the Nanpu depression is distinguished from the others by obviously high content of diasteranes and pregnant series with a relatively lowerδ13C of n-alkane and nearly a "W" shape of carbon isotopic pattern. The type-Ⅲ genetic related oils was discovered in the NP4, 5 tectonic belts. It is observed that the oils in the NP1, 2 tectonic belts, Laoyemiao oilfield and the Tertiary Nm-Es1 of Gaoshangpu and Liuzan oilfield have intermediate biomarker and isotope characteristics between the type-Ⅱ and type-Ⅲ source rocks and the related oils, indicating mixed sources of the oils derived from both the type-Ⅱ and type-Ⅲ rocks. It is found that the related contribution of the Es2+3 source rocks to the mixed oils is up to 82%. We suggest that the Es2+3 is an important set of source rock in the Nanpu depression, responsible for most of the oils. This result is different from the previous ones that most of the oils in the Nanpu depression were derived from the Es1-Ed3 source rocks rather than the Es2+3, which provides essential information for further petroleum exploration of the depression.
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Key words:
- Napu depression /
- mixed oil /
- biomarkers /
- compound specific isotope /
- petroleum geology
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表 1 南堡凹陷部分混源油中Es2+3成因原油相对贡献
Table 1. Percentage of the Es2+3 genetic oils in the mixed oils
油田 井号 井深(m) 层位 贡献量(%) 高尚堡 GC63 2156.4~2224.0 Ng 63 高尚堡 G29-8 2202.8~2206.0 Ng 54 高尚堡 G93 2435.5~2444.0 Ed1 55 高尚堡 G66-28 2625.0~2634.0 Ed1 25 高尚堡 G59-10 2656.0~2705.2 Ed1 42 高尚堡 G17-18 2313.0~2419.2 Ed3 36 高尚堡 G97X5 2816.0~2856.0 Ed3 46 高尚堡 G139X1 3296.6~3303.2 Ed3 52 高尚堡 G76-26 2760.0~3001.6 Es1 82 老爷庙 M23-9 1972.0~1975.0 NgⅠ 33 老爷庙 M26-25 2503.4~2544.0 Ed1 75 南堡油田 NP1-3 3084.4~3154.4 NgⅣ 31 南堡油田 NPX1-5 2797.4~2895.0 Ed1 48 南堡油田 NP12-P801 3084.0~3272.0 Ed1 39 南堡油田 NP13-P1656 3435.0~3620.0 Ed1 29 南堡油田 NP1 2379.8~2410.0 Ed1 51 南堡油田 NP1-29 2355.4 Ed3 40 南堡油田 NP2-3 2649.4~2480.4 Ed1 71 南堡油田 NP23-P2201 2924.4~3020.0 NgⅡ 54 南堡油田 NP2-82 4880.0~4955.0 O 75 -
[1] Jia, Q.S., Li, S.L., Ma, Q., et al., 2006. Geochemical characteristics of hydrocarbon source rocks in the No. 2 structural belt, of the Nanpu subbasin, eastern Hebei oilfield, and source rock correlation. Journal of Geomechanics, 12(4): 469-475 (in Chinese with English abstract). http://d.wanfangdata.com.cn/Periodical/dzlxxb200604010 [2] Jiang, C.Q., Li, M.W., Osadetz, K.G., et al., 2001. Bakken/Madison petroleum systems in the Canadian Williston basin. Part 2: molecular markers diagnostic of Bakken and Lodgepole source rocks. Organic Geochemistry, 32(4): 1037-1054. doi: 10.1016/S0146-6380(01)00079-1 [3] Li, S.M., Jiang, Z.X., Dong, Y.X., et al., 2008. Genetic type and distribution of the oils in the Nanpu depression, Bohai Bay basin. Geoscience, 22(5): 817-823 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-XDDZ200805018.htm [4] Li, S.M., Pang, X.Q., Jin, Z.J., et al., 2010. Petroleum source in the Tazhong uplift, Tarim basin: new insights from geochemical and fluid inclusion data. Organic Geochemistry, 41(6): 531-553. doi: 10.1016/j.orggeochem.2010.02.018 [5] Li, S.M., Pang, X.Q., Li, M.W., et al., 2003. Geochemistry of petroleum systems in the Niuzhuang south slope of Bohai Bay basin—Part 1: source rock characterization. Organic Geochemistry, 34(3): 389-412. doi: 10.1016/S0146-8380(02)00210-3 [6] Li, S.M., Pang, X.Q., Yang, H.J., et al., 2010. Generation, migration and accumulation model for the marine oils in the Tarim basin. Earth Science—Journal of China University of Geosciences, 35(4): 1-11 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQKX201004019.htm [7] Lin, R.Z., Wang, P.R., 1991. PAH in fossil fuels and their geochemical significance. Journal of Southeast Asian Earth Science, 5(1-4): 257-262. doi: 10.1016/0743-9547(91)90034-U [8] Mei, L., Zhang, Z.H., Wang, X.D., et al., 2008. Geochemical characteristics of crude oil and oil-source correlation in Nanpu sag, Bohai Bay basin. Journal of China University of Petroleum, 32(6): 40-46 (in Chinese with English abstract). http://www.researchgate.net/publication/285696311_Geochemical_characteristics_of_crude_oil_and_oil-source_correlation_in_Nanpu_sag_Bohai_Bay_Basin [9] Zhao, Y.D., Liu, L.F., Zhang, Z.H., et al., 2008. Source analysis of oils from the Ordovician in the shoal zone, Nanpu sag, Bohai Bay basin. Geoscience, 22(2): 264-272 (in Chinese with English abstract). http://www.zhangqiaokeyan.com/academic-journal-cn_geoscience_thesis/0201254377281.html [10] Zheng, H.J., Dong, Y.X., Zhu, G.Y., et al., 2007a. High-quality source rocks in Nanpu sag. Petroleum Exploration and Development, 34(4): 385-391 (in Chinese with English abstract). http://www.researchgate.net/publication/298602877_High-quality_source_rocks_in_Nanpu_Sag [11] Zheng, H.J., Dong, Y.X., Wang, X.D., et al., 2007b. The generation and characteristics of source rocks in Nanpu oil-rich depression, Bohai Bay basin. Natural Gas Geoscience, 18(1): 78-83 (in Chinese with English abstract). [12] Zhou, H.M., Cong, L.Z., 1999. Polyphase exthension and its impact on hydrocarbon accumulation in fault basin—case analysis of polyphase rifting in Nanpu depression. Earth Science—Journal of China University of Geosciences, 24(6): 625-629 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQKX199906013.htm [13] 贾齐山, 李胜利, 马乾, 等, 2006. 冀东油田南堡凹陷南堡2号构造带烃源岩地球化学特征与油源对比. 地质力学学报, 12(4): 469-475. doi: 10.3969/j.issn.1006-6616.2006.04.010 [14] 李素梅, 姜振学, 董月霞, 等, 2008. 渤海湾盆地南堡凹陷原油成因类型及其分布规律. 现代地质, 22(5): 817-823. doi: 10.3969/j.issn.1000-8527.2008.05.017 [15] 李素梅, 庞雄奇, 杨海军, 等, 2010. 塔里木盆地海相油气源与混源成藏模式. 地球科学——中国地质大学学报, 35(4): 1-11. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX201004019.htm [16] 梅玲, 张枝焕, 王旭东, 等, 2008. 渤海湾盆地南堡凹陷原油地球化学特征及油源对比. 中国石油大学学报(自然科学版), 32(6): 40-46. doi: 10.3321/j.issn:1673-5005.2008.06.008 [17] 赵彦德, 刘洛夫, 张枝焕, 等, 2008. 渤海湾盆地南堡凹陷滩海地区奥陶系原油油源分析. 现代地质, 22(2): 264-272. doi: 10.3969/j.issn.1000-8527.2008.02.013 [18] 郑红菊, 董月霞, 朱光有, 等, 2007a. 南堡凹陷优质烃源岩的新发现. 石油勘探与开发, 34(4): 385-391. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK200704002.htm [19] 郑红菊, 董月霞, 王旭东, 等, 2007b. 渤海湾盆地南堡富油气凹陷烃源岩的形成及其特征. 天然气地球科学, 18(1): 78-83. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX200701016.htm [20] 周海民, 丛良滋. 1999. 浅析断陷盆地多幕拉张与油气的关系——以南堡凹陷的多幕裂陷作用为例. 地球科学——中国地质大学学报, 24(6): 625-629. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX199906013.htm