澳大利亚大澳湾盆地塞杜纳坳陷构造演化及构造特征分析

STRUCTURAL EVOLUTION AND STRUCTURE ANALYSIS OF CEDUNA SUB-BASIN IN BIGHT BASIN OF AUSTRALIA

澳大利亚大澳湾盆地是目前世界上为数不多的低勘探程度大型沉积盆地,其中塞杜纳坳陷是近几年各大石油公司高度关注的区域。受地震资料品质的影响,前人对塞杜纳坳陷的地层结构、构造演化和构造样式方面的研究还不清楚。本文以重处理二维地震资料为基础,开展大面积的构造解释,通过"回剥法"平衡剖面恢复和重建了塞杜纳坳陷的构造演化历史,与其他类似构造和沉积背景的被动陆缘盆地类比确立了塞杜纳坳陷的双重重力滑脱构造模式。在对塞杜纳坳陷构造特征进行解析的基础上,结合对塞杜纳坳陷的构造差异性分析,总结出塞杜纳坳陷发育的3类共8种主要的圈闭类型,并指出有利圈闭类型发育带的分布,为下步勘探指明了方向。

The Bight Basin of Australia is one of the few large under-explored sedimentary basins in the world,and the Ceduna sub-basin of the Bight Basin has received high attention of oil companies in recent years.However,the stratigraphy,structural evolution and structure types of the sub-basin,constrained by the seismic data with low signal-to-noise ratio,remain unclear up to date.Based on the reprocessed 2d seismic data,regional seismic interpretation has been completed,on the basis of which,the structural evolution history of the Ceduna sub-basin was rebuilt using‘back-stripping＇balanced sections.Duplex gravity driven decollement structure model was finally established on analogy and comparison with other passive margin basins having similar tectonic and depositional background.Further structural analysis of the Ceduna sub-basin was made to reveal the structure features.8types of structural traps under 3classes were generalized and the belt of favorable traps were found,which provide the clue for future exploration in the sub-basin.