黄骅坳陷歧北斜坡区薄层湖相碳酸盐岩沉积相模式及演化特征

Depositional Model and Evolution Characteristics of Thin-Layer Lacustrine Carbonates in Qibei Slope,Huanghua Depression

歧北斜坡区沙-下亚段湖相碳酸盐岩储层较薄（多数集中在0．5～8m），地震资料难以指导内部小层及滩体划分，沉积相模式、演化规律及主控因素认识不清，采用标志层控制、静-动态资料相互拟合的方法，利用岩心、测井、地球化学、古生物等资料，结合示踪剂、吸水剖面等动态资料对薄层湖相碳酸盐岩储层进行综合研究。研究结果表明：超覆地层对比模式符合研究区薄层湖相碳酸盐岩地层真实发育情况，并识别出5期明显的湖岸线；湖水首先沿着港西断层形成的断槽及中部的斜坡低洼区由东向西主发生湖侵；研究区主要发育滨浅湖亚相，包括生屑滩、混积滩等6种沉积微相，生屑滩面积占60％以上；沉积模式显示出沉积早期，地形坡度大、湖侵范围小、滨浅湖面积也最小，主要沉积沿岸碎屑岩砂坝；沉积中后期，水体越过坡折带，滨浅湖面积不断扩大，并迅速超覆至全区，生屑滩沉积面积达到最大的演化规律。歧北斜坡区湖水成化、湖相碳酸盐岩广泛沉积的主要原因，是海侵作用致使湖水初步成化和浅水缓坡台地环境导致混合水蒸发浓缩二次成化双重作用的结果。强烈的剥蚀和填平补齐导致的近似平台型古地貌特征和古生物的大量繁殖，也是控制北斜坡区沉积相类型及演化的主要因素之一。

The lacustrine carbonates of the lower section of Esl Formation in Qibei slope was so thin that it was difficult to use seismic data to correlate the sublayer and understand the depositional model, evolution characteristics and the main control factors. We applyed the method of static and dynamic data matching with each other using of core, well logs, geochemistry, palaeontologic data, trace agent and entry profile to studied the lacustrine carbonates. The results show that overlap stratigraphic correlation method conform to the ture formation development. And five periods lakeshore line obviously to recognized. The lake transgression happened along the Gangxi fault trough and the central low area. Shallow lake is the mainly subfacies, include six kinds of microfacies for biological chip beach and mixed beach, et al. The organic bank accounts for 600//oo of the research area, at early times, the coastal sand dam was mainly developed. On the middle period, the area of shallow lake enlarged rapidly and the biological chip beach organic enlarged rapidly, too. On the late period, both the area of shallow lake and the biological chip beach were largest. The salinization of water and the sediment of lacustrine carbonates are mainly caused by the transgression of sea and the condensation of the water in the shallow gentle slope tableland. The platform-like palaeogeomorphology and the great quantity of reproduction of the prehistoric life are also major control factors of the deposition types and evolution in Qibei slope.