渤海湾盆地是华北的主要含油盆地,自六十年代早期开始钻探以来,迄今已经发现了一些工业油田。其生油层主要是下第三系,因此,对它的研究具有重要的经济意义。本文主要利用地震资料,对该区下第三系以及上第三系馆陶组的地层和沉积特征中的某些问题进行讨论。 一、地层 渤海地区是华北诸含油凹陷的主体与核心,以第三纪地层最发育,厚达7000米以上。其层位包括下第三纪始新世的沙河街组四段—孔店组、渐新世的沙河街组(一、二、三段)、东营组和上第三纪中新—上新世的馆陶组、明化镇组。各层的岩性特征见表1。根据作者的实践和前人的工作得知,整个第三系是一个从水进到水退的完整旋回。水域最大的时期是沙河街组一段沉积时期,东营组沉积时期开始水退。从古生物资料来看,第三系地层主要是湖相沉积。但是,在济阳拗陷的沙四段和黄骅拗陷的沙一段和东营组内,也找到过一些海相化石和自生的海绿石矿物,说明渤海湾曾经和外海有过短期的沟通。然而,由于资料的限制,这种沟通的规模及其产生的影响,至今尚未查清。 根据黄骅及冀中拗陷资料,在沙四—孔店组与老地层之间、沙三、沙四段之间、新、老第三系之间存在着三个明显的不整合,部分地区表现为假整合(图1)。在这三个界面之间的地层内部有无间断面存在,至今没有 Bohai Bay Basin is a major oil-bearing basin in North China. Since the drilling started in the early 1960s, so far some industrial fields have been discovered. Its oil layer is mainly the Tertiary, therefore, its research has important economic significance. This paper mainly uses seismic data to discuss some of the stratigraphic and sedimentary features of the Guantao Formation in the Tertiary and Upper Tertiary in the area. First, the stratigraphic Bohai Sea area is the main body and core of all the oil-bearing sags in North China. The most developed Triassic strata have a thickness of over 7,000 meters. The layers include the fourth member of the Lower Triassic Era of Shahejie Formation, the Kongdian Formation, the Oligocene Shahejie Formation (sections one, two and three), the Dongying Formation and the Neogene-Pliocene Guantao group, Minghua group. The lithological characteristics of each layer are shown in Table 1. According to the author’s practice and predecessors’ work, the entire Tertiary is a complete cycle from water to water. The largest period of water is the sedimentary period of Shahejie Formation, while that of Dongying Formation begins to recede. From the paleontological data, the Tertiary strata are mainly lacustrine sediments. However, some marine fossils and spontaneous pyrochlore minerals have also been found in Sha-4 section of Jiyang depression and Sha-1 section and Dongying Formation of Huanghua depression, indicating that Bohai Bay once had short-term communication with the outer sea. However, due to data limitations, the size of the communication and its impact have not yet been identified. According to the data of Huanghua and Jizhong Depression, there are three obvious unconformities between the Shasi-Kongdian Formation and the old strata, between the Sha 3 and Sha 4 Member, and between the Neo-Oligocene Tertiary. In some areas The performance of the fake integration (Figure 1). There are no discontinuities in the strata between these three interfaces, so far none