塔北隆起区一间房组礁滩沉积体特征

CHARACTERISTICS OF REEF FLAT DEPOSITS IN YIJIANFANG FORMATION AT TABEI UPLIFTED ZONE

塔北隆起区中奥陶统一间房组礁滩沉积体是目前塔河油田油气勘探向南扩展的重要目标,但由于礁滩沉积体通常隐伏于台地相大套石灰岩地层中,长期以来难以通过地震资料及已有的认识进行预测。文章利用钻井及三维地震资料,通过礁滩层地震标定,一间房组及其上下地层的地震相及沉积相分析,建立了坡折带、礁滩沉积体发育带的地震识别标志,阐明了古隆起与坡折带及礁滩沉积体的关系,并建立了相关地质模式。结果表明,对应于中奥陶世塔北古隆起的构造转折带发育的一间房组台内坡折带控制了礁滩沉积体的发育分布,位于该坡折带以北环绕古隆起呈带状分布的8个礁滩沉积体发育区块,将是下一步油气勘探的优选目标。

The reef flat deposits in Middle Ordovician Yijianfang Formation in Tahe uplifted zone are the main exploration targets in the southern Tahe oilfield. However, it is difficult to recognize them by using conventional seismic data and current knowledge as they are often embedded in thick platform limestone. Drilling and 3D seismic data are integrated to perform seismic calibration of reef flat horizons and analyze the seismic facies and sedimentary facies of Yijianfang Formation and the upper and lower formations. Seismic identification marks of slope break zone and development zone of reef flat are recognized, the relationships between paleohighs and slope break zone and reef flat deposits are discussed, and relevant geologic modes are established. The development and distribution of reef flat deposits are controlled by the intra-platform slope break zone in Yijianfang Formation, which corresponds to the structural transform zone in Middle Ordovician Tabei paleohigh. Eight blocks with reef flat deposits that are in zonal distribution around the paleohigh to the north of the slope break zone will be the targets of future exploration.