中国中西部前陆盆地多期成藏、晚期聚气的成藏特征

The multi-stage formation of oil-gas pools and late-stage accumulation of gas in the foreland basins in central and western China

中国中西部前陆盆地具有优越的天然气成藏条件,同时具有晚期成藏的特征。文中在典型气藏解剖的基础上重点讨论了川西、柴北缘和准南缘前陆盆地的成藏过程,从而指出中国中西部前陆盆地具有多期聚集、晚期聚气的成藏特征,明确指出中国中西部前陆盆地具有最主要的两大成藏期,一是燕山晚期,主要是被动陆缘或中部前陆盆地三叠系烃源岩的油气聚集期;二是喜山晚期,受新构造运动影响,主要是西部陆内前陆盆地的中、新生界烃源岩的天然气成藏期和中部周缘前陆盆地的天然气的调整期。新近纪前陆盆地的发育期控制了中国中西部前陆盆地以中生界煤系烃源岩为主的晚期天然气的聚集。

There were excellent geological conditions for formation of gas pools that accumulated in the late stages of foreland basins in middle western China. The paper analyzes the hydrocarbon accumulation of gas pools in the western Sichuan foreland basin, northern Qaidam thrust and the southern Junggar foreland basin. It indicates that the oil-gas fields were formed by multi-stage filling and that the gas pools accumulated in the late stages of the foreland basins. There were two most important stages for oil-gas accumulation in the foreland basins of middle western China. One was the I.ate Yanshanian movement when oil and gas accumulated mainly from source rocks of a passive continental margin and from Triassic foreland basins in central China; another during the Irate Himalayan movement when oil and gas mainly from Meso Cenozoic source rocks of intra-continentai foreland basin in western China and accumulated in gas fields of peripheral foreland basins in central China. The sedimentation of foreland basin in the Neogene had a controlling influence on the late-stage accumulation of gas, which is mainly derived from Mesozoic coal measure.