阿克亚苏三叠系中油组沉积特征及成藏模式

Sedimentary evolution and model of hydrocarbon accumulation at mid oil layers of Triassic in the Akeyasu area

(1.中国石油化工集团公司国际石油勘探开发有限公司,北京100083;2.中国石油大学(北京)资源与信息学院,北京102249;3.教育部油气藏勘探国家重点实验室,北京102249)

Yuan Shukun,Sinopec International Petroleum Exploration and Production Corporation,Beijing 100083,China

塔河油田阿克亚苏地区三叠系中油组砂体分布面积广,沉积厚度大,孔隙度和渗透性好,有利于油气储集,为主力产油层。在地震剖面上识别出差异压实形成的沉积坡折,并结合钻井、岩心和测井等资料,认为在大量物源、坡折带和单河道等因素的控制下,中油组为3级层序内部的低位域湖底扇沉积。随着相对湖平面的下降,在沉积坡折带边缘形成补给水道,物源的不断供应使研究区发育大面积的富砂湖底扇沉积。在内扇的富砂辫状补给水道、中扇辫状沟道和新的上置扇中均见很好的油气显示,但只有侧向封堵性好、砂体厚度大、砂体连通性具有两极性的储集层才有可能成为油气的聚集场所。

In the Triassic of Akeyasu area of Tahe oilfield,mid oil layers contain a deal of sand layers which are large,thick,with good porosity and permeability,which is beneficial for hycrocarbon accumulation,so they are the main oil production layers.We recognized sedimentary slope break by differential compaction through seismic data,then based on drilling,cores and well logging we thought that large supplying,slope break and single channel system were main factors of basin fan development inside the three-order sequence framework.During relative lake-level falling stage,supplying channels system erased low formation on the margin of sedimentary slope break and transported large supplying to the slope out of break.Then sand-rich basin fan formed and developed.Oil and gas showed in the sand of supplying channels,braided stream and new suprafan lobe,but only the reservoir with good lateral sealing,great sand thickness and sand connectivity which other side is connected and another side is sealed could become the oil and gas accumulating places.