准噶尔盆地复合油气系统特征、演化与油气勘探方向

Characteristics and evolution of composite petroleum systems and the exploration strategy in Junggar basin, northwest China

复合油气系统是同一区域内多个油气系统的复合与叠加 ,其范围内的不同油气系统一般不是独立的 ,储集层和盖层往往是共有的 ,所形成的油气藏为多油源混合的结果。准噶尔盆地发育包括 16个油气系统的 4个复合油气系统 ,一般具有多套烃源岩 ,具有多生烃期以及油气多源多期混合成藏的特点 ,同一复合油气系统内多个油气系统的连续性和继承性演化是油气富集的重要因素。玛湖—盆 1井西复合油气系统包括佳木河组油气系统、风城组油气系统和下乌尔禾组油气系统 ;昌吉复合油气系统由侏罗系油气系统和中二叠统油气系统组成 ;东道海子—大井复合油气系统由石炭系油气系统和二叠系平地泉组油气系统组成。这 3个复合油气系统含油气丰度高 ,应是目前准噶尔盆地油气勘探的重点 ,应坚持富油气系统内继承性正向构造单元及其斜坡区勘探 ,并应加强侏罗系的勘探力度。图 5参

The composite petroleum system is the aggregate of several petroleum systems in a certain area. In a composite petroleum system, the petroleum systems share the same reservoirs and caprocks and the petroleum accumulations are usually multi sourced. There are 4 composite petroleum systems in Junggar basin including 16 petroleum systems, in which Muhu West well Pen 1, Changji and Dongdaohaizi Dajing composite petroleum systems have the most importance in the basin. The active source rocks in Muhu West well Pen 1 composite petroleum system are Jiamuhe Formation and Fengcheng of Lower Permian and Xiawuerhe Formation of Middle Permian, they formed three petroleum systems. The active source rocks in Changji composite petroleum system are mainly Middle Permian and Lower Jurassic. The active source rocks in Dongdaohaizi Dajing composite petroleum system are Carboniferous and Middle Permian. The multi sourced and multi phase hydrocarbon accumulation makes the most important characteristics of composite petroleum system in Junggar basin. The continuous and successive development of several petroleum systems is the main factor controlling the richness of hydrocarbon in a composite petroleum system. The emphasis of hydrocarbon exploration in Junggar basin should be focused on the uplifts and the related slopes in the three rich composite petroleum systems.