中国深层天然气形成及保存条件探讨

深层天然气是油气勘探潜在的重要领域,加强深部勘探成为油气区资源发展的必然趋势。笔者将现有与深层气有关的概念进行了甄别分析,最后厘定深层气为埋藏深度大于4500m,在高温、高压和环境介质共同作用下形成和聚集的天然气,就有机质垂向演化而言,主要指沉积层在生油窗以下层位形成和赋存的天然气,并在此基础上对深层气存在的范围进行了探讨。结合有机-无机相互作用,深入研究了深层天然气气源,认为干酪根、聚集型可溶有机质和分散可溶有机质均对深层天然气的形成具有重大贡献,特别是认为分散可溶有机质在叠合盆地可以作为深层气的重要气源。最后根据中国构造演化、烃源发育特点,初步预测了中国深层天然气的分布状况与范围。

Generation and preservation conditions of deep-seated gas in China

Deep-seated gas is an important potential area of petroleum exploration and intensifying the effort to conduct deep-seated exploration is the inexorable trend of resources development in petroleum-bearing regions. In this paper the concepts concerning deep-seated gas are discriminated and analyzed and finally deep-seated gas is defined as natural gas generated and accumulated at >4500 m depth under the combined action of high temperature, high pressure and environment media. In the context of the vertical evolution of organic matter, deep-seated gas mainly refers to the natural gas generated and hosted in sediments below the oil generation window. On that basis, the scope of occurrence of deep-seated gas is discussed and in combination with the interaction between organic and inorganic matter, the deep-seated gas source is studied intensively. The authors think that kerogen, accumulated soluble organic matter and dispersed soluble organic matter make great contributions to the generation of deep-seated gas. Especially, dispersed soluble organic matter in superposed basin may act as an important gas source of deep-seated gas. Finally, according to the tectonic evolution and characteristics of hydrocarbon source rocks, the distribution and scope of deep-seated gas in China is preliminarily estimated.