川东焦石坝地区页岩气特征及其意义

发布时间：2018-02-14 20:32

  本文关键词： 碳同位素 页岩气 五峰组 龙马溪组 焦石坝 石油地质　出处：《地球科学》2017年07期 　论文类型：期刊论文

【摘要】：焦石坝地区五峰组-龙马溪组页岩富集有大量的天然气,但针对页岩气地球化学特征研究还较薄弱,其蕴含的地质意义不甚明确.通过页岩气组分及其碳同位素特征和页岩干酪根的碳同位素特征分析,讨论了页岩气的来源、成因类型和"完全倒转"的碳同位素分布特征.五峰组-龙马溪组页岩具有很好的生烃能力、有机质丰度与含气量的关系有明显的正相关性、甲烷与干酪根相似的碳同位素特征、地层的超压特征等,综合表明研究区天然气应为页岩自生自储的页岩气;页岩气的甲烷含量均超过98%,其碳同位素平均为-29.93‰,反映了成熟度已经达到过成熟干气阶段;相对稳定的ln(C_1/C_2)和快速增大的ln(C_2/C_3)揭示其成因主要为二次裂解气;页岩气碳同位素"完全倒转"的分布特征主要受到在相对封闭环境中的原油裂解生气作用的影响,其"完全倒转"的碳同位素分布特征也反映了研究区良好的页岩气保存、富集条件.
[Abstract]:The shale of Wufeng formation and Longmaxi formation in Jiaoshiba area is rich in a large amount of natural gas, but the study on geochemical characteristics of shale gas is still weak. The source of shale gas is discussed by analyzing the composition of shale gas, its carbon isotopic characteristics and the characteristics of shale kerogen. The shale of Wufeng formation and Longmaxi formation has good hydrocarbon generation ability, and the relationship between organic matter abundance and gas content is obviously positive correlation. The carbon isotope characteristics of methane and kerogen are similar to those of kerogen, and the overpressure characteristics of strata, etc., which indicate that the natural gas in the study area should be shale gas of self-generation and self-reservoir, and the methane content of shale gas exceeds 98 鈥，

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