摘要
四川盆地东部下三叠统飞仙关组鲕滩主要发育在碳酸盐岩台缘带上,而台缘带与海槽密切相关,找到了海槽就意味着找到了鲕滩。以往的沉积相研究主要基于钻井资料,对于海槽和台缘相带边界的划分主要依据井间沉积相的变化趋势作人为的估计,这种划分缺少必要的依据,而地震技术在一定程度上可以弥补这种不足。为了在地震资料上找出准确的海槽位置,利用钻井分析结果,采用层拉平技术消除构造影响,恢复了本区的古地貌特征;运用地震地层学理论,横向上划分了沉积相,纵向上分析了沉积演化史;采用一种新的沉积相分析方法,以钻井层序、地震层段和地震反演为基础,在反演剖面上进行地层格架解释、沉积环境解释、以及岩性和储层解释,更清晰地描绘出本区的沉积相变化特征。最终结果显示:地震划分的海槽范围比钻井划分的范围更窄,边界更准确;在无沉积间断的前提下,下三叠统飞仙关组沉积早期是继承上二叠统沉积方式的欠补偿沉积,而非前人描述的快速充填沉积。
The oolite beach of the lower Triassic Feixianguan Formation in eastern Sichuan basin developed in themargin of carbonate platform, and platform margins are always related to ocean trough. If ocean trough has beenfound, then oolite beach will be found. But previous sedimentary facies studies in this region were mainly basedon drilling data, and failed to provide enough evidence for differentiating ocean trough from boundaries of plat-form margin. This paper proposed to adopt seismic techniques to better delineate ocean trough. Firstly, layerflattening was used to remove structural effects and recover paleogeomorphologic feature. Secondly, horizontalsedimentary facies was determined and vertical depositional history analyzed with seismic stratigraphic theory. Fi-nally, based on drilling stratum sequence, seismic sequencer, and seismic inversion, a new analysis method ofsedimentary facies was adopted to perform stratum framework nterpretation, sedimentary environmental inter-pretation, as well as lithology and reservoir interpretation, and characterize the variations of sedimentary facies.Two conclusions were drawn. The extent of ocean trough delincated by seismic data was narrower than that bydrilling data, and the ocean trough boundary determined by the seismic data was more accurate. The early deposi-tion of the lower Triassic Feixianguan Formation was starved sediments that inherited the sedimentary mode ofthe upper Permian, differing from the rapidly filling sedimentary mode as described by previous studies.
出处
《勘探地球物理进展》
2004年第5期371-375,共5页
Progress in Exploration Geophysics
