准噶尔盆地西北缘沉积特征及油气成藏规律——以五、八区佳木河组为例

准噶尔盆地西北缘前陆冲断带是剖析西准噶尔地区盆山耦合关系、盆地成因与造山带演化、沉积体系发育的关键地段。准噶尔盆地西北缘五、八区二叠系佳木河组为火山岩、火山碎屑岩、碎屑岩组成的混积地层，佳木河组下亚组分为2个三级层序PSQ1、PSQ2，中亚组和上亚组分别为三级层序PSQ3和PSQ4，下亚组主要充填火山岩和火山碎屑岩，中亚组及上亚组主要充填扇三角洲为主的粗碎屑沉积物。五、八区佳木河组主要发育扇三角洲相、火山口及近火山口相、远火山口相，扇三角洲砂体和火山岩体是最重要的油气储集体。研究区已知油气藏多分布于扇三角洲平原亚相、前缘亚相和火山口及近火山口相中，但是否能成藏关键在于构造（裂缝）、成岩作用、油源、圈闭等与储集层的空间匹配关系。图4参18

Sedimentary characteristics and hydrocarbon accumulation rules in northwestern Junggar Basin: A case from Jiamuhe Formation of No.5 and 8 area

The foreland thrust belt of the northwestern margin of the Junggar Basin is a key area for studying coupling between the basin and mountains, basin origin and orogenic belt evolution, and development of sedimentary systems. The Permian Jiamuhe Formation in No.5 and 8 area is composed of volcanic, volcaniclastic and clastic rocks. The low subunit of the formation consists of 2 third-order sequences PSQ1 and PSQ2, and the middle and upper subunits are PSQ3 and PSQ4. The low subunit is filled mainly by volcanics and volcaniclastic rocks, and the other two subunits are filled by coarse fragments of dominant fan delta. The facies developed in the studied area includes fan delta, crater, proximal crater and distal crater facies, and most known hydrocarbon accumulations are found in the former three facies. The volcanics and sands of fan delta are the main reservoirs. The pool-formation is dependant on the spatial configuration of structure, diagenesis, source, trap, etc.