摘要
南黄海中部隆起海相地层埋藏浅,是南黄海盆地油气勘探的重点,但由于缺乏钻井资料约束,中部隆起中-古生界的地层属性一直存在争议.大陆架科学钻探CSDP-02井是南黄海中部隆起第一口钻井,也是南黄海盆地钻遇地层最深的一口全取心井.本文在分析大陆架科学钻探CSDP-02井的岩心、测井和相应多道地震资料基础上,明确了中部隆起中-古生界的地层属性:在新近系充填沉积之下,依次发育三叠系下统青龙组下段、二叠系上统大隆组、龙潭组,二叠系下统孤峰组、栖霞组,石炭系船山组、黄龙组、和州组和高骊山组,泥盆系五通群和志留系高家边组、奥陶系.结合地球物理测井曲线分析与区域地质认识,确定了地震反射界面T2、T8、T9、T10、T11的反射特征与对应的地质界面.中部隆起地层分布特征整体受南黄海构造运动的影响,早古生代地层平缓,断裂不发育,加里东运动造成志留系上统及中下泥盆统沉积缺失,石炭系-二叠系在中部隆起广泛发育,厚度大,二叠系最大沉积厚度约1900m,中生界残留地层分布局限,主要保存下三叠系,地层厚度变化范围较大.
With a shallow depth,the marine strata in the central uplift of the South Yellow Sea basin is the focus target of oil and gas exploration.However,due to lacking drilling data,the geological age and strata attributes of this area are controversial for a long time.Well CSDP-02 ofthe"Continental Shelf Drilling Program"is the first borehole in the central uplift,also the deepest whole-coring well in the South Yellow Sea basin.Based on the cores,well logs and multichannel seismic data,this paper clarifies the geological age and rock types of Mesozoic-Paleozoic strata in the central uplift.The strata below the Neogene sedimentary filling is the lower Qinglong Formation of Lower Triassic,the Dalong-Longtan Formation and Gufeng-Qixia Formation of Permian,the Chuanshan-Huanglong-Hezhou-Gaolishan Formation of Carboniferous, Wutong group of Devonian,Gaojiabian Formation of Silurian and Ordovician.Based on the drilling results,the distribution of Mesozoic-Paleozoic marine sedimentary strata of the uplift is defined and the long debate about the properties of marine residual strata can be ended.In addition,the reflection features and corresponding geological interfaces of seismic reflectors(T2,T8,T9,T10,T11)are inferred.Of them,T2 is the bottom boundary of the Neogene sediment system as well as the marker bed of the research area with high energy,stable waveforms.T8 is the Indosinian surface,which corresponds to the top of Qinglong Formation with high amplitudes and low frequency.T9 is a reflection of wave trough with high amplitudes and low-medium frequency,which we propose is the reflection of the bottom of Dalong Formation.With obvious energy variation in line XQ09-2,T10 is the reflection of wave peak and represented by medium-high amplitude and high frequency and T11 is a discontinuous reflector of Devonian.The strata distribution of the central uplift is influenced by the tectonic movement of the South Yellow Sea basin.Specifically,the strata are almost horizontal in the early Paleozoic with little faulting.During the Caledonian,the upper Silurian and lower Devonian are lost.Strata of Carboniferous-Permian developed extensively,the maximum thickness of the Permian is 1900 meter.To Mesozoic,denuded by the Indochina movement,while the residual strata is mainly lower Triassic with great thickness variations.