河坝地区嘉陵江组三级层序及高频层序研究

Third-order and High-frequency Sequences of Jialingjiang Formation in Heba Area

根据前人研究,结合研究区钻井(岩心、测井)资料,运用层序地层学的原理和方法,将川北河坝地区嘉陵江组划分为2个三级层序,自下而上依次称为下部三级层序、上部三级层序。每个三级层序仅发育保存了海侵体系域和高水位体系域,并且阐明了三级层序关键界面的识别标志及三级层序特征。同时,进一步将该组划分为6个四级层序和15个五级层序,简述了高频层序发育特征。建立了以上部三级层序顶界为拉平面的三级层序及高频层序对比格架。横向上,三级层序及高频层序发育厚度变化不大,比较稳定,横向对比性好;纵向上,下部三级层序海侵体系域沉积厚度相对上部三级层序较厚,而高水位体系域沉积较之要薄。

Based on drilling data obtained from Heba area of northern Sichuan Basin,the Jialingjiang formation can be divided into two third-order sequences of both lower and upper ones from below,in which only transgressive system tract(TST) and high system tract(HST) are developed.In this study,the identification mark of key sequence boundary and the sequence features are all presented ;and then,this formation can be subdivided into six forth-order sequences and fifteen fifth-order sequences ;the development characteristics of high-frequency sequence are also illustrated ;and the third-order sequence,taking top boundary of upper third-order sequence as a base level,and the correlation framework of high-frequency sequence are also established.Results show that(1) horizontally,the development thicknesses of both third-order and high-frequency sequences are pretty stable ;(2) vertically,the sedimentary thickness of TST for lower one is higher than that of upper one however,the sedimentary thickness of HST is smaller than that of upper one.