渤海莱州湾凹陷KL油田沙河街组混积背景下的沉积特征与沉积演化

Sedimentary Characteristics and Sedimentary Evolution in Mixed Sediments Background of Shahejie Formation in KL Oilfield, Laizhou Bay Depression, Bohai Bay Basin

渤海湾盆地莱州湾凹陷KL油田地区古近系沙河街组发育了陆源碎屑岩和碳酸盐岩的混合沉积构造,国内外学者在莱州湾凹陷地区已做了一些岩相古地理方面研究工作,但KL油田地区的混合沉积研究至今未涉及.由于KL油田地区钻遇沙河街组沙三下亚段的井较少(迄今全地区钻遇沙三下亚段井9口),本文充分利用有限的钻井资料,结合岩心资料、分析化验资料、单井沉积相解剖以及地震相分析,对渤海湾盆地莱州湾凹陷KL油田地区碳酸盐岩台地混合沉积特征以及沉积演化模式进行了较为深入的探讨.研究表明,KL油田古近系沙河街组主要以扇三角洲沉积体系为主,混积岩主要发育在沙河街组沙三下亚段,而沙三下亚段发育三种不同的沉积环境:KL-1井区发育辫状河三角洲,中部KL-4井区发育滨浅湖混积滩坝,东部KL-9井区在Ⅰ油组处于潍北凸起物源供给区,发育了扇三角洲.沙三下亚段沉积时期,沉积物在碳酸盐岩台地上进行混合沉积,狭义上表现为混积岩,主要类型包括:泥质灰岩、含泥灰岩、灰质粉砂岩;广义上表现为混积层系,主要类型包括:含陆源碎屑一碳酸盐混积岩、含碳酸盐一陆源碎屑混积岩、碳酸质一陆源碎屑混积岩.

The Shahejie Formation of the Paleogene in the KL oilfield area of the Laizhouwan depression,Bohai Bay Basin has developed a mixed sedimentary structure of terrigenous clastic rocks and carbonate rocks.Domestic and foreign scholars have done some research on lithofacies palaeogeography in the Laizhouwan depression.However,the study of mixed sedimentation in the KL oilfield area has not been covered so far.Because there are fewer wells in the lower part of the Shahejie Formation in the KL oilfield area(so far,9 underground wells have been drilled in the Shahejie Formation),this paper makes full use of limited drilling data,combined with core data,analytical laboratory data,and single well sedimentary facies.Anatomical and seismic facies analysis,the mixed sedimentary characteristics and sedimentary evolution patterns of carbonate platform in the KL oilfield of Laizhou Bay Sag,Bohai Bay Basin are discussed in depth.The study shows that the Shahejie Formation of the Paleogene in the KL oilfield is dominated by the fan delta sedimentary system.The mixed rock is mainly developed in the lower part of the Shahejie Formation,and the Shahejie Formation develops three different sedimentary environments:the KL-1 well.The braided river delta is developed,and the coastal shallow lake composting beach dam is developed in the middle KL-4 well area.The eastern KL-9 well area is located in the source belt supply area of??the Weibei uplift in the I oil group,and a fan delta is developed.During the sedimentary period of the Lower Member of the Shahejie Formation,sediments were mixed and deposited on the carbonate platform.The narrowly defined areas were mixed rocks.The main types include:argillaceous limestone,marl-bearing limestone,and limestone siltstone.The main types include:terrigenous clastic-carbonate mixed rock,carbonate-terogenous clastic mixed rock,and carbonate-terogenous clastic mixed rock.