安哥拉深水水道地质知识库建立及应用

Establishment and Application of Geological Data Base on Deep-water Channels in Angola Block

利用浅层(上新统)三维高频地震资料的剖面、切片和属性信息,对安哥拉陆坡区深水水道特征和定量关系进行研究,在复合水道和单一水道两个层次上建立了安哥拉地区浊积水道定量化地质知识库。研究结果表明:研究区单一水道活动方式类似于曲流河点坝模式,即单一水道仅沿侧向(垂直于古流向)整体迁移,不存在整体"下游扫动"分量,且在平面上其侧积复合体呈"同心半环状",单一水道的砂体以垂向加积方式充填在轴部,厚度向边部减薄;单一水道的宽度与深度、弯曲弧长与弯曲度之间存在较好的正相关性;复合水道样式按照内部单一水道的活动方式分为(I)侧向迁移、(II)斜列迁移和(III)摆动迁移三类模式,且(I)类主要发育在高弯曲段(弯曲度>1.3),II类和III类主要发育在低弯曲段(1<弯曲度≤1.3);该地质知识库成功应用到实际三维地质建模中,具有推广价值。本文研究不仅可以完善深水水道定量分布模式,而且可以有效降低此类油田开发风险,具有理论和实际意义。

To establish a quantitative geologic database at composite and single channel level for deep water slope channel systems in Angola,the characteristics and their quantitative relationships were carefully studied based on high frequency 3D seismic profile,slice and attribute data of shallow Pliocene deposits. The results indicate that the single channel activity pattern is somewhat similar to the point bar model in a meandering river. It migrates only in lateral direction( orthogonal to the paleocurrent direction) without ' downstream sweep' component,and the lateral accretion composites form a ' concentric half ring' shape in plane view,whereas the sandbodies fill in the axis by vertical accretion,and thinning towards channel edge. Good positive correlations can be widely observed between width and depth,meander-arc height and sinuosity in single channels. Based on the single channel activity pattern,the composite channel pattern can be classified into 3 types as( I) lateral migration,( II) inclined migration,and( III) swing migration. Type( I) develops in higher sinuosity section( sinuosity > 1. 3),whereas type( II) and type( III) develops mainly in lower sinuosity section( 1 < sinuosity≤1. 3). The database is applied in geological modeling successfully,and can be extended to the similar reservoirs. The research in this paper has theoretic and practical significance,because not only the quantitative distribution channel models can be established and improved,but also the risk on development about this type of reservoir can be decreased.