摘要
寒武系烃源岩是塔里木盆地海相油气最主要的来源之一,长期以来对该套烃源岩发育的沉积环境表述多样,对于极少资料控制的烃源岩预测带来诸多不确定性。利用露头和新的钻井、地震资料,在震旦纪—寒武纪成盆作用分析的基础上,通过沉积结构及成烃生物组合研究寒武系烃源岩发育的沉积环境,进而约束下寒武统烃源岩的分布。研究认为,塔里木盆地寒武纪西"台"东"盆"的沉积格局,经历了早寒武世缓坡到中-晚寒武世弱镶边台地的演化,下寒武统泥质烃源岩主要分布于中-外缓坡。与盆地东部下寒武统西山布拉克组烃源岩一样,盆地西部下寒武统玉尔吐斯组-肖尔布拉克组下段烃源岩的成烃生物组合表现为由底栖藻类占优向浮游藻类占优的转变,与早寒武世海进-海退沉积序列相对应。塔里木盆地寒武系烃源岩主要发育于深水陆棚环境,可进一步划分为陆棚相泥质烃源岩和陆棚相碳酸盐质烃源岩,前者以底栖藻类生物相占优势,后者以浮游藻类生物相占优势,海平面升降变化导致两类烃源岩具有叠加、交错的分布特征。
The Cambrian source rocks are considered as one of the most important source of marine oil and gas in Tarim Basin. Previous literatures documented various descriptions of their depositional settings,causing confusion in prediction of source rocks,especially those with no sufficient data. Analyses of outcrops,new drilling and seismic data,and assumptions of prototype basin from the Sinian to Cambrian,were used to study the sedimentary environment of the rocks through a perspective of sedimentary texture and hydrocarbon generating organisms to work out constraints over their distribution.The results show that the Cambrian sedimentary framework of Tarim basin can be characterized as ＂Western Platform and Eastern Basin＂. It evolved through a carbonate ramp in the Early Cambrian and a feebly rimmed platform in the MiddleLate Cambrian. The source rocks of the Lower Cambrian were widely distributed in the middle-outer ramp. The Lower Cambrian Xishanbulake Fm source rocks in eastern Tarim Basin and the Lower Cambrian Yuertusi-Xiaoerbulake Formation in western Tarim Basin have the same bio-precursors assemblage which change from benthic algae of to planktonic algae,corresponding to the Early Cambrian progressive-retrogressive sedimentary succession. Regional sedimentary-tectonic evolution background and lithology and bio-precursors reveals that the Cambrian source rocks were developed in the deep shelf environment predominantly,and could be further divided into muddy source rocks and carbonate source rocks. The muddy source rocks were dominated by benthic algal,while the carbonate source rocks were dominated by planktonic algae. In vertical,the muddy source rocks and carbonate source rocks are superimposed on each other.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2015年第6期880-887,共8页
Oil & Gas Geology
基金
中国石化科技部项目(P12004)
关键词
沉积环境
烃源岩
寒武系
塔里木盆地
depositional environment
source rock
Cambrian
Tarim Basin
