中国中-西部4种新生代挤压盆地成藏地质条件及成藏期次

新生代挤压盆地是我国中-西部的重要油气勘探领域。根据挤压盆地的发育部位、盆地基底、充填层序、构造叠加和盆山耦合形式等条件,本文在我国中-西部识别出准(噶尔)西北缘型、四川盆地西缘型、柴(达木)北缘型和准(噶尔)南缘型等4种新生代挤压盆地,前两者发育海西晚期—印支期前陆盆地,后两者具有喜马拉雅造山期的再生前陆盆地特征。对准西北缘、四川盆地西缘、柴北缘和准南缘新生代挤压盆地的对比研究表明,它们在烃源岩、储盖组合等成藏条件上存在明显的差异,而晚期前陆发育对柴北缘型和准南缘型挤压盆地烃源岩演化具有明显的控制作用。在不同新生代挤压盆地典型油气藏解剖研究的基础上,认为燕山期及之前是准西北缘型和四川盆地西缘型挤压盆地主要的成藏期,喜马拉雅造山期则主要表现为准西北缘型挤压盆地的油气藏保存和四川盆地西缘型挤压盆地油气藏的调整和定型;喜马拉雅晚期是柴北缘型挤压盆地最主要的成藏期,而多期前陆盆地的准南缘型挤压盆地具有多期成藏的特征,但喜马拉雅晚期的油气成藏最为重要。

GEOLOGICAL CONDITIONS AND OIL-GAS FILLING PERIODS OF 4 TYPE CENOZOIC COMPRESSIONAL BASINS IN CENTRAL-WESTERN CHINA

The Cenozoic compressional basins in central-western China is a very important area for oil-gas exploration. According to devlopment location, basement, sedimentary succession, structural superposition and basin evolution, 4 type Cenozoic compressional basins, namely, the northwestern Junggar Basin, the western margin of Sichuan Basin, the northern Qaidam Basin and the southern Junggar Basin, could be identified in central-western China. The forland basin was developed in northwestern Junggar and western Sichuan in Late Hercynian and Early Indosinian, whose basin-orogeny relation was decoupled by the Himalayan orogeny. The Ceno- zoic foreland basin was developed in northern Qaidam and southern Junggar in Himalayan movement, in the latter the Hercynian-Indosinian foreland basin once well occurred. The 4 type Cenozoic compressional basins had various features for reservoir formation conditions such as source rocks and reservoir-seal associations, with obvious control function on source rock thermal evolution in the Cenozoic foreland basins. According to study on the typical hydrocar- bon reservoirs in different compressional basins, it could be concluded that the main hydrocar- bon accumulation for the northwestern Junggar and western Sichuan Basins occurred before and in the period of Late Yanshannian, with reservoir adjusting in western Sichuan Basin and reservoir preservation in the northwestern Junggar Basin in the period of Himalayan movement, the main hydrocarbon accumulation in the northern Qaidam Basin being the period of Late Himalayan movement, and hydrocarbon accumulation occurring in several periods in the southern Junggar Basin with most important period being in Late Himalayan movement.