胜利滩海地区馆上段—明化镇组底部河流类型及演变

Fluvial Types and Evolution of the Upper Member of Guantao Formation and Bottom of Minghuazhen Formation of Neogene in Shengli Offshore Area

以(密闭)岩心精细观察描述、粒度分析、密井网测井资料分析为主要研究手段,结合区域古构造、古气候以及基准面旋回变化研究成果,对胜利油田滩海地区新近系馆陶组上段至明化镇组底部河流类型及河型演变规律开展研究。结果表明,研究区馆陶组上段和明化镇组底部主要发育辫状河、分汊河和曲流河三种河流类型。其中,辫状河主要发育在研究区馆上段7砂组、研究区南部和中部馆上段6砂组下部和南部馆上段1+2砂组;曲流河主要发育在研究区中部馆上段3砂组和北部馆上段5砂组上部到3砂组;分汊河则比较广泛地发育于除上述地区和砂组以外的其他砂组。控制和影响研究区河流演变的三大因素依次为构造作用、古气候和基准面变化,受其影响,研究区从馆上段—明化镇组底部即存在辫状河到分汊河(再到曲流河)的正向演变关系,也有分汊河到辫状河、曲流河到分汊河的反向演变关系,而非持续地从高能量河流向低能量河流演变的过程。

The types and evolutionary process of rivers in the upper member of the Neogene Guantao Formation and bottom of the Minghuazhen Formation in the offshore area of the Shengli oilfield were studied by careful observation and description of sealed drill cores,grain size analysis and detailed well logging data analysis,together with an in⁃vestigation of regional paleostructure,paleoclimate and base-level cyclic change.It was found that,in general,three types of river developed in the study area:braided,meandering and anabranching rivers.Braided rivers were mainly developed in no.7 sand stratum of the upper member of the Guantao Formation,and in the lower part of no.6 sand stratum of the upper member of the Guantao Formation at the southern and central parts of the study area,and in nos.1 and 2 sand strata of the upper member of the Guantao Formation in the southern part of study area.Meandering riv⁃ers were developed in the no.3 sand stratum of the upper member of the Guantao Formation in the central part of the study area,and in the northern part of study area from the upper part of no.5 to no.3 sand strata in the upper member of the Guantao Formation.Anabranching rivers were widely developed in the other sand group.The three major influ⁃encing factors were tectonism,paleoclimate and base-level change.Their effect was a forward evolutionary relation⁃ship from braided to anabranching river(then to meandering river)and a reverse evolutionary relationship from anabranching to braided river,and meandering to anabranching river from the upper member of the Guantao Forma⁃tion to the bottom of Minghuazhen Formation.The process was not continuous from high-energy rivers to low-energy rivers.