中国大中型气田分布的地质特征及主控因素

Distribution of large-middle sized gas fields in China: geological characteristics and key controlling factors

研究大中型气田形成的地质条件和主控因素,对于天然气工业的发展有重要意义。中国目前只有西藏及福建、浙江、湖南等少数省、自治区没有工业性气田,除志留系、泥盆系外,从前震旦系到第四系都有天然气田(藏),但是只在西部、中部、东部及近海4个含气区的11个盆地有储量大于100亿m3的大中型气田(统计不包括南海南部海域及台湾省),主力气层分布也有明显地域性,与富气凹陷及烃源岩时代、盆地发展历史密切相关。结合中国地质条件及盆地(地区)具体的地质条件,总结了中国形成大中型气田的10条主控因素。由于天然气易于运移散失、难以保存,中国又是新近纪以来构造运动比较活跃的地区,因此,充足的气源、生气强度较高的富气凹陷以及大区域良好的封闭保存条件,是所有盆地形成大中型气田的必备要素,也是诸多地质因素中最为重要的因素,研究晚期、超晚期天然气成藏、定型,对中国天然气成藏及评价天然气前景有重要意义。

The research on the geological conditions and key factors controlling the formation of large-middle sized gas fields is of great significance to the development of natural gas industry. The industrial gas fields have been found all around China except the Tibet autonomous region, Fujian, Zhejiang and Hunan Province. As for strait graphic horizons, gas fields occur from pre-Sinian to Quaternary, except in Silurian and Devonian. Large-middle sized gas fields with over 10 billion cubic meters have only been discovered in 11 basins in west, central and east China, and offshore areas （southern South China Sea and Taiwan have not been included in the statistics）. The major gas reservoirs are distributed with apparent regional ties, and closely related to the gas-rich depressions, ages of source rocks and evolutional history of the basins. The 10 key factors controlling the formation of large-middle sized gas fields summarized from the geological conditions in China must be integrated with the specific geological conditions to analyze the gasbearing conditions in the basins. China is characterized by relatively active tectonic movements since Neogene, abundant gas generation, gas-rich sags with relatively high gas-generating capacity and good regional sealing and preservation conditions are essential for the formation of large-middle sized gas fields in all basins, and they are also the most important ones among various geological factors. Late and ultra-late accumulation study is important for evaluating the prospects of natural gas in China.