晚期成藏对大气田形成的重大作用  

Important role of the formation of gas accumulations in the late stage in the formation of large gas fields

作　　者：戴金星[1] 卫延召[1] 赵靖舟[1] 

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《中国地质》2003年第1期10-19,共10页Geology in China

基　　金：国家科技攻关项目(96-101)资助。

摘　　要：截至2001年底,中国发现21个大气田,累计探明天然气储量17953×108m3,占全国天然气总储量的59.80%。天然气的分子小、重量小、难被吸附而易扩散。成藏早的大气田,若无继续获得气源,随扩散时间增长损失气量不断增加,使大气田演变为中、小型气田,甚至散失殆尽。因此,晚期成藏是大气田形成的必要条件之一。中国盆地具有多旋回性,多旋回性往往是后续的旋回损害和降低前旋回聚集气藏的保存条件和储量,故晚期成藏就避免此弊,有利于大气田的形成。晚期成藏的大气田的生气高峰期既可是与成藏期同步或基本同步,以及储集层与气源岩的层位较新,也可以是成气高峰期比成藏期早,储集层和气源岩层位老。By the end of2001,21large gas fields had been discovered in China,and their cumulative explored reserves of gas in place reached17953 × 10 8 m 3 ,taking up59.80%of China ' s total gas reserves.Gas molecules are small,hard to be adsorbed and ready to diffuse.Large early-formed gas fields will lose their quantity and become small or medium-sized ones or even be depleted completely owing to long-continued gas diffusion,if no gas source replenishes the supply.Therefore,the formation of gas accumulations in the late stage is one of the fundamental conditions for the formation of large gas fields.Basins in China are polycyclic in nature.The tectonic cycle of succeeding basin usually reduces or damages the reserves and preservation conditions of gas accumulations in the preceding basins.So,the formation of gas accumulations in the late stage can avoid this defect and is favorable for the formation of large gas fields.The period of peak gas generation of large gas fields resulting from late-stage accumulation is synchronous or nearly synchronous with the period of accumulation,and their source and reservoir rocks are younger.Sometimes,the peak generation period is earlier than the period of accumulation and their source and reservoir rocks are older.

关 键 词：大气田 晚期成藏 中国 储集层 气源岩 保存条件 

分 类 号：P618.13[天文地球—矿床学]