中国陆上天然气地质特征与勘探领域

中国陆上含天然气盆地主要有克拉通盆地、前陆盆地、陆内裂谷（断陷-拗陷）盆地和走滑（拉分）盆地。发育煤层、陆相暗色泥岩、海相暗色泥岩和海相碳酸盐岩4类气源岩；储层主要为碎屑岩、碳酸盐岩和火山岩储层，以中-低孔渗为主；天然气藏类型多样，主要发育构造气藏、构造-岩性气藏、地层-岩性气藏和裂缝性气藏4种类型。不同类型盆地大气田形成的主控因素不同，如克拉通盆地大气田主要受古隆起、台缘礁滩、大型缓坡等因素控制。中国陆上已形成鄂尔多斯、塔里木、川渝、柴达木及东部5大气区，天然气田（藏）从前寒武系、古生界、中生界至新生界均有分布；从盆地类型看，以克拉通盆地和前陆盆地资源最为丰富。天然气下一步勘探重点领域较多，在克拉通盆地、前陆盆地及裂谷盆地（松辽盆地深层），评价有利勘探区带（块）33个，勘探面积为84.6×10⁴km²，资源潜力近50.9×10¹²m³，体现了广阔的勘探前景；天然气勘探接替领域主要有生物气、煤层气和页岩气等，在中国勘探潜力较大，是未来勘探的重点。

Geological Characteristics and Exploration Fields of Subaerial Natural Gas in China

The main subaerial gas-bearing basins in China include craton basins,foreland basins,intracontinental rift (fault-depression) basins and strike-slip (pull-apart) basins.In these basins,four kinds of gas source rocks are mainly developed,including coal bed,terrestrial dark shale,marine dark shale and carbonate.Clastic reservoirs,carbonate reservoirs and volcanic reservoirs,which have low-middle porosity and permeability,are the three main reservoir types.Various types of gas pools are found and classified into four types such as structural gas pool,structural-stratigraphic gas pool,stratigraphic-lithological gas pool and fractured gas pool.Large gas fields in different basins have different controlling factors.Take large gas fields in craton basin as an example,their formation is controlled by paleo uplift,reef flat in platform margin,and large gentle slope,etc.Five gas regions have been discovered in subaerial region,including the Ordos,Tarim,Chuanyu,Qaidam and Eastern gas region.The gas regions are distributed in Precambrian,Palaeozoic,Mesozoic and Cenozoic strata.The gas resource is most abundant in craton and foreland basins.There are many exploration fields in future.It is evaluated that there are 33 favourable exploration regions,84.6×10⁴km²exploration area and 50.9×0¹²m³potential resource distributed in craton basin,foreland basin,and rift basin (the deep zone of Songliao Basin),which indicates a wide exploration prospect.The succeeded exploration fields include biogas,coal bed gas and shale gas etc.These exploration fields,which have great exploration potential,are the exploration emphasis in the future.