准噶尔盆地白家海-五彩湾地区侏罗系基准面旋回划分及隐蔽油气藏

Jurassic stratigraphic base-level cycle and subtle oil reservoir in Baijiahai-Wucaiwan,Junggar Basin,NW China

白家海—五彩湾地区位于准噶尔盆地东北缘,侏罗系构造圈闭不发育,隐蔽油气藏已成为主要勘探目标。为满足隐蔽油气藏勘探的需要,提高储集层、隔层预测的精度,根据高分辨率层序地层学基准面旋回原理,通过钻井、测井和地震资料综合分析,在侏罗系识别出12个基准面升降的转换面,根据基准面旋回划分,将侏罗系自下而上划分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ等6个三级层序、11个四级层序。根据精细地层对比分析,侏罗系隐蔽油气藏的圈闭主要是位于层序Ⅲ基准面下降期湖退三角洲前缘砂体和层序Ⅴ、Ⅵ基准面上升期的河道砂体。

Baijiahai-Wucaiwan is located in the NE Junggar Basin, where the subtle oil reservoirs could be the major play targets. According to the stratigraphic base level, six mid-term base-level cycles and eleven shore^term base-level cycles can be recognized in the Jurassic. Based on the drilling,well logging, 3-D seismic data,and the base-level cycle pattern of high-resolution sequence stratigraphy,eleven transfer levels of the base-level cycle are recognized, from which the high-resolution sequence stratigraphic framework is established, suggesting that the subtle oil reservoirs are mainly developed in the sand body in front of the delta in the descending half-cycles and channel-sand in the ascending half-cycles.