琼东南盆地深水区梅山组丘状反射体地质解释  

GEOLOGICAL INTERPRETATION OF MOUNDY REFLECTORS OF MEISHAN FORMATION IN DEEPWATER AREA OF QIONGDONGNAN BASIN,SOUTH CHINA SEA

作　　者：王云[1] 冯杨伟[2] 张功成 WANG Yun1 , FENG Yangwei2 ZHANG Gongcheng3(1. Department of Geology, Northwest Unzverszty ,Xi＇ an 710069China; 2. Xi＇an Center of Geological Survey, China Geological Survey, Xi＇an 710054, China; 3. CNOOC Research Center ,Beijing 100027,Chin)

机构地区：[1]西北大学地质学系,陕西西安710069 [2]中国地质调查局西安地质调查中心,陕西西安710054 [3]中海油研究总院,北京100027

出　　处：《矿物岩石》2018年第1期111-119,共9页Mineralogy and Petrology

基　　金：公益性基础地质调查项目(DD20189612);国家科技重大专项项目(2016ZX05026-007);国家自然科学基金项目(41502081)

摘　　要：琼东南盆地深水区梅山组一段层序内发育大量丘状反射体,目前共有油气钻井6口,二维地震测线约12 000km,测网密度大多为6km×8km。三维地震区两块面积共约1 700km^2。以国内外研究现状与进展及区域地质资料为基础,立足研究区钻井资料、二维地震与三维地震剖面资料,通过地震测线剖面追踪,刻画丘状反射体地震反射特征和几何形态,进而开展波阻抗反演、类比与对比分析,结合成礁古构造背景研究等,分类对丘状反射体给出合理地质解释。研究结果表明:琼东南盆地深水区梅山组一段发育4类丘状反射体,地质解释为生物礁、等深积岩丘和底辟构造3类地质体。生物礁为斑礁群和台地边缘礁,发育在古地貌高地的清水环境,跟周围地层相比具有同期地层厚度增大特点。斑礁群为中强震中频丘状地震相,分布在南部斜坡缓坡单斜型台地的高部位;台地边缘礁为强震中频扁平丘状地震相,主要发育在南部隆起碳酸岩台地边缘。单个生物礁外形呈丘状、凸透镜状,具有礁脊和礁沟,内部可见前积,翼间双向上超,顶、底强反射,轮廓清晰。垂直于古水深方向礁前比礁后陡,呈微不对称,平行于古水深方向礁体呈对称—微不对称。波阻抗反演显示礁顶底统一连续,斑礁群波阻抗值达到7kg/m3*m/s左右,台地边缘礁波阻抗值达到7.5kg/m3*m/s左右。等深积岩丘为中强震中连低频丘状地震相,分布在南部斜坡带单斜型台地台缘斜坡。等深积岩断面上呈丘状,丘与丘之间界线模糊不清,在平面上呈长条状,波阻抗值为5.8kg/m3*m/s左右,与生物礁显著区别。岩浆底辟显著特点是具有"根"。Numerous moundy reflectors developed during the depositional stage of upper seg- ment of Meishan Formation in deepwater area of Qiongdongnan basin. There have been six wells and 12 000 km 2D seismic lines in the area,with the seismic grid density of 6 km×8 km in most places,and two 3D seismic blocks with the total area about 1 700 km2. Based on present situation and development at home and abroad, in view of regional geologic information, footing on drilling data,2D and 3D seismic data, by means of tracing layer in seismic sections, the seismic reflection characteristics and geometry of moundy reflectors were described. Then the inversion of wave im- pedance of moundy reflectors, analogy and comparison were launched in consideration of palaeo- structure background of deposition stage of upper Meishan Formation. Finally, reasonably geo- logic interpretation of these moundy reflectors was given. It shows that the geologic interpreta- tion of moundy reflectors of Meishan Formation in deepwater area of Qiongdongnan Basin were reefs,contourite mounds and diapir structure. Reefs were patch reef group and platform edge reef,lying at palaeogeomorphic highland with clear water, reef layer is much thicker than other layers without reef at the same depositional stage. Patch reef group were mounded seismic facie- ses with moderate-strong amplitude and medium frequency, distributed at high placement of southern ramp area. Platform edge reef, occurred at carbonatite platform edge of south uplift zone,is characterized by strong amplitude medium frequency platy moundy seismic facies. The sin- gle bioherm shape is moundy or lenticular,and has crest and canal of its own with foreset bedding inside, bidirectional uplap between limbs, strong reflection at top and bottom, clear outline. Reef is slight asymmetry between fore-reef and back-reef in the case of perpendicularity to palaeo bathy- metric orientation,while symmetry to slight dissymmetry,paralleling to the palaeo bathymetric o- rientation. The wave impedance inversion sectio

关 键 词：琼东南盆地 梅山组 丘状反射体 生物礁 等深积岩丘 

分 类 号：TE122.1[石油与天然气工程—油气勘探]