沉积基准面变化分析技术及其应用

ANALYSIS TECHNIQUES OF SEDIMENTARY BASE LEVEL AND THEIR APPLICATION

沉积基准面分析是研究层序地层形成、进行等时地层单元划分与对比的关键环节。从地震、测井等资料中可求取定性或半定量的沉积基准面变化曲线：（１）在地震剖面上正确识别和区分盆缘上超、滨岸上超和水下上超的基础上，经过差异沉降、脱压实和地层剥蚀恢复等一系列校正，可获得反映基准面变化的上超点曲线；（２）在对测井曲线进行谱分析识别出米兰柯维奇旋回的基础上，采用校正的费希尔图解方法可编制出反映基准面变化的可容纳空间变化曲线。在塔里木盆地北部利用地震和测井资料，采用不同方法求得的沉积基准面变化曲线有着很好的一致性，并用于层序地层划分、层序级别确定、井间层序对比和盆地的构造、沉积演化史分析。

The analysis of sedimentary base level is the key to the identification and correlation of isochronostratigraphic units.The qualitative or semi quantitative baes level curves could be constructed based on the analyses of seismic data and well logs.(1)The onlap curve that represents baes level changes could be obtained by the correlation of differential subsidence,decompaction and stratigraphic restoration based on the identification of basin margin onlap,coastal onlap and marine onlap in seismic sections.(2)Milankovitch cycles could be identified through spectral technique of well logs;accommodation curve reflecting base level cycles could be established by means of corrected Fischer plot.Sedimentary base level curves obtained by different analysis techniques of seismic sections and well logs in North Tarim show good consistency,and they could be in the analyses of sequence stratigraphy,determination of sequence orders,correlation of interwell strata units and the study of tectonic and depositional histories of a basin.