Abstract: There are three main types of natural gas formation in oil-bearing areas of Eastern China,they' re oil-type &pyrolysis gas in deep Tertiary Depression, biodegradation &thermal action gas in moderate-shadow Tertiary System,and coal bed gas with high evolution extent in Paleozoic &Mesozoic System.The formation conditions of enriching belts for the natural gas in terrestrial rich-oil basins of Eastern China are:1)high anomaly of geotemperature field or early biological modification condition in hydrocarbon source rock;2)the source rock with high thermal evolution hasn' t evident expulsion history of hydrocarbon in the period of moderate thermal evolution or the first thermal evolution is not high enough;3)there' s a compressing &shearing stress environment in structured belts with rich gas on the background of regional tension stress;4)relative low potential energy environment among a variety of fluid potential system and 5)better combination such as reservoir,cap rocks and preservation.

Key words: Eastern China, natural gas, origin, enriching belts, distribution

摘要： 我国东部油区天然气主要有第三系深凹陷油型热裂解成气、第三系中浅层生物改造热作用成气、古—中生界煤系高演化成气三种主要类型.东部陆相富油盆地内天然气富集带的形成条件主要有:烃源层系内高异常地温场或早期生物改造条件的存在;高热演化烃源岩在中等热演化期没有较显著的排烃史或一次热演化程度不高;聚气构造带为区域拉张背景下的扭压应力环境所形成;各种流体势系统中的相对低势环境以及具有良好的储、盖及保存条件等.

关键词: 中国东部, 天然气, 成因, 富集带, 分布规律