三角洲沉积的结构——成因分类与编图方法

Texture-genetic Classifications and Mapping Methods for Deltaic Deposits

地质学中各类沉积体系的分类方案历来受到广大学者重视,尤其是三角洲做为沉积学研究与油气勘探开发的重点与热点,近年来人们越来越强调对其进行结构—成因分类。本文回顾了三角洲沉积体系研究的发展历程,指出了其存在的主要问题,进而系统论述了三角洲的结构—成因分类的具体含义与分类方案,阐明了这种分类方法的优点。同时,又提出了一套能够反映三角洲结构—成因特点的沉积相编图方法及编图中应注意的一些具体问题。这种编图方法从高分辨层序地层对比与沉积微相导向的小层对比出发,强调在恰当的编图单元约束下,注重岩相组合与沉积序列进行沉积类型识别,采用岩、电、震结合的方法进行多参数套合编图,使沉积相图能够更好地反映砂体的粒度粗细、分布特征及沉积成因,以便使储层的预测性得到充分体现。

Classifications for various depositional systems have been the general attention of sedimentary geologists. In recent years, sedimentologists have emphasized increasingly on the texture-genetic classification of deltaic depositional system which are the focus and hot issue for sedimentology study and hydrocarbon exploration and development. This paper aims to review the development of the study for deltaic depositional system, points out the problems, demonstrates the specific meaning and scheme of texture-genetic classification for deltaic deposits systematically, and illustrates the advantages of this type of method. Simultaneously, a method of facies mapping which indicates the characteristics of texture-genetic classification for deltas is proposed with the related specific issues in this paper. Based on the principles of high resolution sequence stratigraphy and layer correlation droved by depositional facies, this mapping method emphasizes identifying depositional facies type by litho-facies assemblages and vertical successions. In order to reflect the grain size, distribution and sedimentary genesis of sand-body and represent the reservoir prediction adequately, multi-parameters from lithology, well logs and seismic are nested during mapping.