276 / 2019-07-09 15:15:15

歧南断阶带沙一段重力流类型、展布及勘探潜力分析

重力流沉积；砂体类型；砂体展布预测；勘探潜力分析；沙一段；歧南断阶带,gravity flow deposit; sand body types; sand body distribution prediction; exploration potential analysis; Es1 formation; Qinan fault step belt

以岩心、测井、地震及分析化验资料为基础，对渤海海域歧南断阶带沙一段重力流沉积形成机制、识别特征及沉积模式进行了研究。研究发现，研究区沙一段重力流沉积机制共分为滑动滑塌、泥质碎屑流、砂质碎屑流及浊流四种类型。为进一步明确重力流砂体展布范围及规律，以边界断层海四断层为研究对象，选取13个取样点对断层活动性进行了分析，结果表明断层下降盘第4和第9样点位置处断层活动性较弱，发育横向背斜，为重力流砂体发育位置，受断层活动对古地貌影响，研究区共发育两种重力流砂体组合类型：洪水成因的湖底扇型及滑动滑塌成因的滑塌浊积扇型，其中湖底扇型主要发育于断裂坡折带位置处，平面上向凹陷中心方向依次发育泥质碎屑流成因的内扇亚相沉积、砂质碎屑流成因的中扇亚相沉积及浊流成因的外扇亚相砂体；滑塌浊积扇型多发育于陡坡带位置处，平面上向凹陷中心方向主要发育滑动滑塌成因的滑动滑塌堆积体及浊流成因的远源浊积岩砂体。在以上分析的基础上，从重力流沉积发育位置、圈闭条件及储层物性三个方面对四种成因重力流砂体的勘探潜力进行了分析，认为砂质碎屑流成因的湖底扇中扇亚相砂体沉积勘探潜力最大，其次为滑动滑塌成因砂体，浊流成因砂体次之，泥质碎屑流成因的内扇亚相砂体潜力最差。
Formation mechanism, recognition characteristics and depositional model of Es1 formation in Qinan fault step belt were studied based on core, well logging, seismic and experimental data. Analysis results show that the mechanism of gravity flow sediments can be divided into four types, which are slide and slump deposits, muddy debris flow, sandy debris flow and turbidity flow deposits. To further clarify the distribution range and regularity of gravity flow deposit, Hai 4 fault was taken as an example, and 13 sampling points are selected to analyze boundary fault activity. The result shows that the fault activity is weak at the fourth and the ninth points, these locations mainly develop transverse anticline resulting in gravity flow reservoir development. Affected by the influence of fault activity made on the paleogeomorphology, the gravity flow combination types in the study area can be classified into two types, which include sublacustrine fan caused by flood and slump turbidite fan type caused by the sediment slide. The sublacustrine fan mainly develops at the location of slope break zone, which include the inner fan caused by the muddy debris flow, middle fan formed by sandy debris flow and outer fan deposit to the depression center direction. The slump turbidite fan mainly develops at the location of steep slope belt, which is composed of slump condensed section and distal turbidite. On the basis of the above analysis, exploration potentials of four types of sand bodies are analyzed on the basis of comparative studies of sand body location, trap conditions and reservoir physical properties. The results show that the middle fan formed by sandy debris flow have the best exploration potential, followed by the slide and slump deposits, the turbidity flow deposits take the third place, and the exploration potential of muddy debris flow deposits is the worst.