摘要:
发育于琼东南盆地乐东凹陷、陵水凹陷、松南低凸起的中央峡谷西段,早期充填了厚达700 m的深海重力流沉积.基于两口钻井和两块三维地震资料,对研究区内中央峡谷早期的沉积演化进行了研究.通过分析地震剖面波组特征和对比井震资料,将峡谷充填划分为5个沉积期次;在井震对比的基础上,结合反射特征、地震切片及属性分析,识别出四种主要的沉积类型:水道复合体、水道—天然堤、浊积席状砂、块体流.沉积期次1主要为水道复合体,沉积期次2和3主要为水道—天然堤,沉积期次4主要为块体流和水道—天然堤,沉积期次5主要为块体流和浊积席状砂.峡谷DS1~DS3主要受轴向物源控制,以浊流沉积为主,富砂;DS4~DS5逐渐受北部陆坡物源控制,以块体流沉积为主,富泥.浊流沉积是峡谷内优良的储集体,普遍发育于峡谷充填下部,与上部块体流沉积可以形成良好的储盖组合,具有较好的油气勘探潜力.
Abstract:
The west segment of Central Canyon in Qiongdongnan Basin, which wanders from Ledong, Lingshui depression to Songnan low uplift, received over 700 m of gravity flow deposits in the early stage. Mainly based on 2 wells and 2 blocks of 3D seismic data, this paper studied the sedimentary architectures and evolution stages of Yinggehai Formation in the canyon. The canyon infill were divided into 5 depositional sets (DS) vertically according to seismic wave group and seismic-well tie; 4 significant depositional types were recognized by analyzing reflection features, seismic slice and attribute analysis: channel complex (CC), channel-levee(C-L), sheet-like turbidity sand(STS) and mass transport deposits (MTDs). DS1 was primarily CC, DS2 and DS3 were mainly C-L, DS4 consisted of both MTDs and C-L while DS5 was mostly MTDs and STS. During early stages (DS1~DS3), the canyon was dominated by axial sand-rich turbidity currents, while in later stages (DS4~DS5), the canyon was gradually controlled by mass transport deposits from northern slope and rich in mud. Turbidite deposits are ideal reservoir which lays in the lower parts of the canyon, together with the upper MTDs can form perfect reservoir-seal assemblage, thus shows great potential for hydrocarbon exploration.
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