中国大气田勘探领域与前景

Exploration domain and prospect of giant gas fields in China

2000—2010年,中国共发现大型气田19个,累计探明天然气地质储量达5.98×1012 m3,开展大气田勘探领域的研究,对于解决储量接替问题、保障国家能源安全等都具有十分重要的意义。为此,分析了大气田形成的气源基础,认为中国天然气资源量大(70.44×1012 m3),分布相对集中于松辽、四川、塔里木、鄂尔多斯等7个含油气盆地,层系上主要分布于中生界和上古生界。总结了大气田的分布规律:①中国陆上沉积盆地多具有旋回叠加地质结构特征,古生界与中生界过渡时期的区域海陆沉积旋回形成间互分布的广覆式煤层、砂岩和泥岩,垂向上控制着大气田的分布层位;②烃源岩是大气田形成与分布的决定性因素,生气强度大于10×108 m3/km2的稳定沉积、高效聚集区也能形成大气田;③区域盖层严格控制着大气田的分布。依据天然气的资源潜力、大气田的分布规律和各盆地的天然气勘探现状,认为未来大气田主要有5个勘探领域:致密砂岩领域、礁滩和岩溶领域、火山岩领域、内陆板块活动边缘快速沉积盆地领域和煤层气—页岩气领域。

During 2000 - 2010, there were 19 giant gas fields in total having been found in China and their cumulative proven reserves of natural gas in place reached up to 5.98 trillion ma. The research of exploration domains for giant gas fields is of great significance to solve the issue of reserve replacement, to guarantee the national energy safety, and so forth. In view of this, this paper first ana lyzes the foundation of gas sources for the above giant gas fields. The results show that there is a huge natural gas reserves in China with about 70.44 trillion ma , which are distributed mainly in the Mesozoic and upper Paleozoic strata and concentrated in about 7 oil- and gas-bearing basins such as Songliao, Basin, Tarim, Ordos basins, etc. The distribution law of giant gas fields is then summa rized. （1） Most continental sedimentary basins in China are of multi-cycle superimposed characteristics; the sedimentary cycle of regional marine and continental deposits in the transition period between the Mesozoic and Paleoszoic era resulted in the interbedding and extensive covering of coal beds, sandstones, and mudstones, which decides upon in vertical the distribution horizon of a giant gas field. （2） Source rocks are one of decisive factors for the formation and distribution of a giant gas field; a steady deposit with the gas generating strength of more than one billion ma per km2 or an efficient accumulation zone could possibly become a giant gas field. （3） Regional cap rocks strictly control the position of a giant gas field. On the basis, this paper, in combination with gas resource potential and the status quo of natural gas exploration in all basins, concludes that there are five main exploration domains for more giant gas fields to be found in the future： tight sand gas reservoirs, reef flat and karst reservoirs, volcanic gas reservoirs, those gas reservoirs in the rapidly deposited basins at the active interior plate margins, and coalbed methane and shale gas reservoirs.