中国北方地区深层-超深层天然气轻烃分布规律及其应用研究

Compared with middle-shallow oil and gas exploration, the exploration and development of deep-ultra deep natural gas in China is relatively poor. However, with the deepening of oil and gas exploration and the improvement of drilling technology, it has become an inevitable trend for exploration to extend to deep and ultra-deep areas. Conventional gas geochemical analysis, such as gas composition, carbon and hydrogen isotope analysis, can be used to study the origin and source of natural gas. But for deep-ultra deep natural gas, the main component is methane, and the degree of evolution is relatively high. It is difficult to rely solely on conventional gas analysis methods. It is necessary to add to the research of light hydrocarbon geochemistry, which contains a lot of fingerprint information. This project intends to summarize the geochemical characteristics of light hydrocarbons in deep-ultra deep natural gas in north China and establish the identification chart of light hydrocarbon indices through the analysis of typical deep-ultra deep natural gas samples, the thermal simulation experiments of source rocks and crude oil, and the full-two-dimensional gas chromatography scanning method. In addition, to explore the role of light hydrocarbons in the formation of deep-ultra deep natural gas, and to clarify the material source and light hydrocarbon generation mechanism of it.

与中、浅层油气勘探相比较，中国深层—超深层天然气勘探开发程度较低，但伴随着油气勘探工作的不断深入与油气钻探技术的提高，勘探向深层和超深层领域延伸已经成为必然趋势。常规天然气地球化学分析如气体组成、碳和氢同位素分析的确可以进行成因、来源研究，但对于深层—超深层天然气来说，其主要成分为甲烷，而且演化程度较高，单纯依靠常规天然气分析手段常捉襟见肘，需要通过含有大量指纹信息的轻烃地球化学研究锦上添花。本项目拟通过对中国北方盆地包括塔里木、渤海湾和松辽盆地深层—超深层天然气样品进行轻烃分析，辅以烃源岩及原油热模拟实验，借助全二维气相色谱轻烃扫描方法，总结中国北方深层—超深层天然气轻烃地球化学特征，并建立其轻烃指标鉴别图版，同时探讨轻烃在深层—超深层天然气形成中的作用，以明确深层—超深层天然气的物质来源及轻烃生成机理。

油气勘探工作向深层和超深层领域延伸已经成为必然趋势，尤其是天然气领域。轻烃含有丰富的地球化学信息，是油气源对比、刻画油气生成机理和演化阶段的重要手段，深层—超深层天然气的气体组分（C1—C4）所含地球化学信息有限，需要轻烃研究辅助解决气源对比及成因机理问题。本研究内容主要包括：①研究中国北方深层—超深层天然气轻烃地球化学特征；②建立深层—超深层天然气轻烃指标鉴别图版；③探讨轻烃在深层—超深层天然气形成中的作用。通过采集50口深层—超深层天然气样品，除中国北方地区外，还包括四川盆地龙岗地区等天然气样品，另收集500余个中国各盆地深层-超深层天然气地球化学数据。建立了中国典型盆地深层—超深层天然气组分、同位素、轻烃特征数据大表，对塔里木及四川盆地深层—超深层进行深入剖析、对比，建立了一套可用于深层—超深层天然气生源及成熟度鉴别的参考图版；通过对不同煤系烃源岩和油页岩热模拟产物进行地球化学分析实验，探讨了整个热模拟过程中轻烃的演变，剖析了轻烃对深层—超深层天然气生气的影响作用，为超深层天然气资源潜力评价和勘探发现提供了重要理论依据；所建立的实验分析方法可用于提高采收率国家重点实验室分析测试项目，创造收益的同时为中国天然气勘探提供地球化学基础。