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东海盆地西湖凹陷、珠江口盆地珠二坳陷、琼东南盆地和莺歌海盆地天然气地质储量占中国近海天然气总地质储量的70%以上,这几个盆地或凹陷构成了中国近海重要的天然气富集带。这些盆地或凹陷天然气主要为煤型气,天然气来源与腐殖型和腐泥腐殖型烃源岩密切相关,主要烃源岩为海陆过渡相煤系烃源岩,其次为陆源有机质海相烃源岩,有机质均主要来源于陆生高等植物。主要烃源岩形成期,东海盆地西湖凹陷和南海北部具有湿热的气候条件,有利于高等植物的生长和发育。在这种有利的气候条件下,河流三角洲体系是控制富气盆地烃源岩形成的主要因素,河流三角洲体系的发育有利于生物生长的营养物质输入,有利于陆生高等植物有机质的输入,有利于三角洲煤系烃源岩的发育,也有利于海相烃源岩的发育,河流—三角洲体系的发育程度决定了烃源岩的发育程度和生烃潜力。
The natural gas reserves in the Xihu Sag of the East China Sea Basin, the Pearl River Mouth Basin, the Pearl River Mouth Basin, the Qiongdongnan Basin and the Yinggehai Basin account for over 70% of the total geological reserves of China’s offshore natural gas. These basins or hollows constitute important gas-rich Set with. The main natural gas in these basins or sags is coal-type gas. The source of natural gas is closely related to humic-type and sapropelic humic-type source rocks. The main source rocks are the transitional coal-bearing source rocks, followed by terrigenous organic marine hydrocarbons Source rock, organic matter are mainly from terrestrial higher plants. The main source rock formation period, the East China Sea Basin Lake depression and the northern South China Sea with hot and humid climatic conditions conducive to the growth and development of higher plants. Under this favorable climatic conditions, the delta system of the river is the main factor controlling the formation of source rocks in the gas-rich basins. The development of the delta system in the river is conducive to the input of nutrients for biological growth and is conducive to the input of organic matter from terrestrial higher plants. Benefiting the development of deltaic source rocks in the delta also favors the development of marine source rocks. The degree of development of the river delta system determines the degree of hydrocarbon source rock development and hydrocarbon generation potential.