乍得Doseo盆地白垩系层序地层与沉积体系  

Cretaceous sequence stratigraphy and depositional system in Doseo Basin, Chad

作　　者：刘为付[1] 

机构地区：[1]东北石油大学地球科学学院,黑龙江大庆163318

出　　处：《中南大学学报（自然科学版）》2016年第6期1981-1989,共9页Journal of Central South University:Science and Technology

基　　金：东北石油大学培育基金资助项目(XN2014119);国家自然科学基金资助项目(U1262106)~~

摘　　要：利用层序地层学理论,综合分析地震和钻井资料,对乍得Doseo盆地白垩系地层层序界面特征、沉积类型、沉积体系分布及生储盖组合进行系统分析。研究结果表明:研究区识别出6个层序界面,划分为2个二级层序,5个三级层序;三级层序内依准层序组叠置样式,可细分为低位体系域、湖侵体系域和高位体系域。沉积类型主要有5种类型,即滨浅湖、三角洲、辫状三角洲、冲积河流及半深湖—深湖。沉积演化形成4种沉积体系,即分布广泛的湖泊沉积体系、盆地南缘三角洲沉积体系、盆地北缘辫状三角洲沉积体系及早期SQ1层序和晚期SQ5层序中发育的冲积河流沉积体系,前三者主要分布在SQ2,SQ3和SQ4层序中,构造活动及古地貌控制沉积体系的分布。生储盖组合可分为顶生式、正常式和自生自储式,SQ2,SQ3和SQ4层序能形成有利生储盖组合,预测有利生油区和储集区,湖侵期的暗色泥岩是最有利生油区,低位期和高位期的砂体是有利储集区。Combining the theory of sequence stratigraphy with the seismic and drilling data, the sequence boundary characteristics, the sedimentary types, the sedimentary system and the source-reservoir-cap assemblages of Cretaceous strata in Doseo Basin of Chad were systematically studied. The results show that 6 sequence boundaries are identified in the study area, which are divided into 2 second-order sequences and 5 third-order sequences. Based on the superimposed patterns of the parasequence sets, each of the third-order sequence is subdivided into the lowstand system tract, the transgressive system tract and the highstand system tract. The distribution of sedimentary facies and the prediction of sedimentary system are achieved in the third-order sequence. 5 types of sedimentary facies are recognized, namely,shore-shallow lake, delta, braided delta, fluvial deposit and semi-deep lake-deep lake facies. 4 chief sedimentary systems are established, i.e： lake sedimentary system widely distributed in each third-order sequence, delta sedimentary system distribution in the south of the basin, braided delta sedimentary system distribution in the north, and alluvial river sedimentary system distributed in the early sequence SQ1 and the late sequence SQ5, and the first three systems are main developed in sequence SQ2, SQ3 and SQ4. The distribution and evolution of the sedimentary systems are controlled by tectonic activity and palaeogeomorphology. According to the disposal relationship of source-reservoir-cap rocks, three types of associations are divided： the type with source rocks in the upper and reservoirs below; the type with source rocks below and reservoirs in the upper; the type with self-sourced reservoirs. The favorable source-reservoir-cap rocks aredistributed in sequence SQ2, SQ3 and SQ4, and the most favorable source area and reservoir area are predicted： the source area is developed in the dark mudstone of the transgressive system tract; the reservoir area is developed in the sand bodies of the lowstand syste

关 键 词：乍得 Doseo盆地 白垩系 层序地层 沉积体系 

分 类 号：P539.2[天文地球—古生物学与地层学] P618.13[天文地球—地质学]