柴达木盆地一里坪地区新近系油气成藏条件

The Hydrocarbon Accumulation Conditions of Neogene in Yiliping Area of Qaidam Basin

通过对一里坪地区的烃源岩、储盖层、圈闭等各项成藏关键因素分析,确定制约新近系油气藏形成的主控因素。认为,一里坪地区烃源岩主要为N21层段和部分N22层段暗色泥质岩,其有机质丰度相对较低,有机质类型以腐殖型为主,成熟门限为2 800 m;储集层主要为粉砂岩,物性偏低;圈闭主要为背斜、断背斜等。据构造演化史、沉积史、生烃史分析,确定新近系烃源岩主要生烃期与圈闭发育史较为匹配,形成“内储式原生油气藏”的成藏模式。确定出碱山和碱石山为近期勘探的目标。

The dominating factors controlling hydrocarbon accumulation of Neogene are determined by analyses of the source-reservoircap rocks and traps in Yiliping area. The result shows that the source rock assumes dark mudstone in N2^1 zone and N2^2 zone, dominated by humic-type organic matter of relatively low abundance, maturity threshold depth of 2 800 m; the reservoir rock is characterized by sihstone; the traps are anticline and faulted anticline. The major hydrocarbon-generating stage of Neogene source rock well matches the period of trap formation, shaping the original hydrocarbon accumulation mode of internal storage, according to study of the structural evolution history, sedimentation history and hydrocarbon generation history. It is concluded that Jianshan and Jianshishan in this area could be regarded as exploration targets in the near future.