【作者】 庞小军；

【导师】 王冠民；

【作者基本信息】 中国石油大学 ， 地质学， 2011， 硕士

【摘要】 本论文在利用二维、三维地震、钻/测井及岩心等资料的基础上,运用沉积学、层序地层学、地震解释等理论和方法,对渤中凹陷古近系盆地的结构、层序地层格架、沉积相类型、沉积相展布及其控制因素进行了探讨,并总结了古近系砂体的分布规律。研究表明,渤中凹陷古近系盆地主要表现为断坳结构,其中孔店组及沙河街组以断陷为主,东营组以坳陷为主。古近系地层由老到新依次发育孔店+沙四、沙三、沙二、沙一、东三+东二下、东二上+东一等6个层序。盆地整体上经历了1次大规模扩张(孔店至东二下层序)和萎缩(东二下层序至东一层序)的演化过程,构成了一个完整的地层旋回。在沉积相类型上,沙河街组主要以较粗的近源砂砾岩体为主,发育冲积扇、近岸水下扇、扇三角洲、辫状河三角洲等沉积相类型。东营组东三段(对应层序的湖侵体系域)以近源砂砾岩体为主,主要发育冲积扇、近岸水下扇、扇三角洲、辫状河三角洲等沉积相类型;东二下亚段至东一段(对应层序的高位域)的沉积相类型则发生明显改变,以大型远源曲流河三角洲、辫状河三角洲为主,砂砾岩体主要沿凹陷长轴方向发育。在沉积体系的形成过程中,一级控制因素(一级断裂带及古气候)控制了区域沉积背景,形成凸起与凹陷相间的古地理格局及湖盆范围;二级控制因素(二级断裂带)控制了局部古地貌,以及碎屑物质的运输通道和沉积场所;三级控制因素(物源、坡折带、古水系、湖平面变化等)主要控制了沉积相类型、规模及砂体平面分布和垂向变化。砂砾岩体分布规律有以下几个特点:纵向上,沙河街组各层序以小型近源粗粒冲积扇、扇三角洲、水下扇、辫状河三角洲等砂体为主,东营组各层序以长轴大型远源较细粒曲流河三角洲砂体为主,局部发育短轴中型的辫状河三角洲、扇三角洲等砂体,具有明显的层位性;横向上,凹陷陡坡带发育裙带状进积的粗粒砂砾岩体,缓坡带及凸起之间多以点状进积的较细粒砂砾岩体为主,具有明显的区带性。不同时期的物源具有继承与演化并存的特点:孔店组到东三段以近源粗粒砂体为主,东二下亚段到东一段以远源较细粒砂体为主,二者的物源具有各自的继承性,基本都是在早期的基础上发育和迁移的,但不同时期的沉积相类型、砂体规模和沉积位置等都存在一定的变化。更多还原

【Abstract】 By use of two-dimensional, three-dimensional seismic, drilling/logging and core, and theories and methods of sedimentology, sequence stratigraphy and seismic interpretation, the thesis discusses Paleogene structure, sequence stratigraphic framework, sedimentary facies, sedimentary facies and its controlling factors in Bohai Basin, Paleogene sandbodies distribution principles are summarized as well.The studies shows that, the structure of faulted-depression were developed in Paleogene of the Bohai Basin, and Kongdian and Shahejie formation have experienced faulted depression, Dongying formation has experienced depression. From lower to upper strata, six stratigraphic sequence of Paleogene, Kongdian and Sha-4, Sha-3, Sha-2, Sha-1, Dong-3 and Dong-2-lower, Dong-2-upper and Dong-1were developed. Basin has experienced the a large-scale expansion (Kongdian to Dong-2-lower) and atrophy (Dong-2-lower to Dong-1) , which constituted a complete stratigraphic cycle.When it comes to the types of sedimentary facies, Shahejie formation was mainly formed by coarse glutenite bodies that from nearly source area, and constituted by alluvial fans, subaqueous fans, fan deltas, braid river deltas, etc. Dong-3(Corresponding to lake transgression systems tract) was mainly formed by coarse glutenite bodies from the near source area, and also mainly constituted by alluvial fan, subaqueous fan, fan delta, braid river delta facies. The sedimentary facies were changed from Dong-2-lower to Dong-1(Corresponding to highstand systems tract), which are fine-grained meander river deltas and braid river deltas from far source area, and the glutenite bodies mainly develope along long axis of the depression.During the formation of the sedimentary system, level one (level one fault and Paleoclimate) controlling factor controls regional sedimentary background, uplifts and depressions were developed one after another;level Two (level two fault) controls the local ancient landscape, as well as transport routes and places of the sediments; level three (source area, slope breaks, ancient water system and the level change of the lake) mainly controls the sedimentary facies type, size as well as plane distribution and vertical changes of sand.The principles of sandbodies’distribution are, Shahejie formation was the coarse glutenite bodies from the near source area, and developed alluvial fan, subaqueous fan, fan delta and braid river delta vertically. Dongying formation mainly developed large fine-grained meander river delta from far source area, and local short-axis developed medium-sized braid river delta and fan delta sand bodies partly, which caused different layers. Horizontally, steep slope of depression developed crony-like coarse glutenite bodies, and mainly developed the dot fined-grained glutenite bodies between gentle slopes and uplifts with obvious characteristics of zones. Provenance in different periods had the characteristics of inheritance and evolution, Kongdian formation and Dong-3 were mainly constituted by coarse glutenite bodies from the near source area, fine-grained glutenite bodies from far source area developed from lower Dong-2 to Dong-1. Both of the formations have their own source of inheritance, and based on the early development and migration, but there were certain changes among sedimentary facies type, location and deposition of sand scale in different periods.更多还原