金湖凹陷阜宁组二段混合沉积研究

金湖凹陷是苏北盆地的主要含油气凹陷,阜宁组二段沉积时期广泛发育陆源碎屑与湖相碳酸盐的混合沉积,结合研究区内岩芯、录井、测井等资料对金湖凹陷阜二段的混合沉积进行了系统研究。其中,金湖凹陷阜二段沉积时期,混合沉积微观上表现为陆源碎屑组分与碳酸盐组分混合沉积形成混积岩,宏观上表现为陆源碎屑岩—碳酸盐岩层系、陆源碎屑岩—混积岩层系、碳酸盐岩—混积岩层系和混积岩层系;混积类型主要发育渐变式和复合式混合沉积,少量发育突变式混合沉积。通过对比分析区域地质背景、岩石学特征、沉积环境等,建立了阜二段混合沉积相模式。对研究区的混合沉积控制因素进行了讨论,认为其主控因素为阜二段沉积时期的海侵作用,同时构造作用、气候条件、湖平面变化、物源等也对研究区混合沉积有重要的影响。

Mixed Sedimentation in the Second Member of the Funing Formation in the Jinhu Sag

The Jinhu Sag contains the main oil-bearing blocks in the northern Jiangsu Basin, and mixed sediments of terrigenous fragments and lacustrine carbonates are widely developed in the Second Member of the Funing Formation in the Jinhu Sag. This paper describes a systematic study of the mixed sedimentation of the Second Member of the Funing Formation in Jinhu Sag, with cores, mud logging, well logging, and other study area data acquisition methods. This work discovered that, in the sedimentary period of the Second Member of the Funing Formation in Jinhu Sag, the mixed sedimentary rock with the best micro performance was mixosedimentite formed by mixed deposits of terrigenous fragments and carbonate components, and the best macro performance was obtained from a layered system of terrigenous rock-carbonate rock, terrigenous rock-mixosedimentite, carbonate rock-mixosedimentite, and mixosedimentite. The types of mixed deposits include mainly blended mixed deposits, complex mixed deposits, and some saltatory mixed deposits. This paper carefully analyzes the mixed deposits in the study area, including their geological settings, petrological characteristics, and depositional environments, establishes a mixed sedimentation model, and discusses the controlling factors of the mixed deposits. The main controlling factors are the transgressive effects of the Second Member of the Funing Formation. Tectonic action, climatic conditions, lake surface changes, and provenance also have important effects on the mixed deposits in the study area.