海底水道储层构型对泥岩底辟区同沉积构造的响应机理

As the major target of deep-water hydrocarbon exploration, submarine-channel reservoirs, which are associated with the syndepositional structure, are difficult to be developed due to their significant heterogeneity. Therefore, the detailed response mechanism of submarine-channel architecture to the syndepositional structures tend to be the focus to address such issue, which, however, have rarely been studied especially in the mud diapir zone. This study focuses on submarine channels and syndepositional structures developed in the mud diapir zone of Niger Delta slope. On the basis of high-resolution 3D seismic data from the shallow surface, we investigate the tectonic styles and geometrical parameters of the syndepositional structures through the quantitative structural geometry analysis, and establish the quantitative architectural patterns of submarine channels around different structure units by the 3D seismic geomorphology approach. Then, the relationship between geometrical and architectural parameters of syndepositional structures and submarine channels is further probed to show the detailed response mechanism of submarine channels to syndepositional structures, which in turn is significant for efficient development and oil recovery enhancement.

与同沉积构造有关的海底水道是深海油气藏勘探的主要目标，其内部储层结构复杂多变、非均质性强，这大大增加了该类油气藏的开发难度，弄清海底水道储层构型对同沉积构造的响应机理是解决开发问题的关键理论基础，而当前相关研究十分薄弱，特别是在泥岩底辟区这种响应机制尚不十分清楚。本项目以尼日尔三角洲陆坡典型泥岩底辟区为例，以浅层高频地震信息为原型，以海底水道储层构型对同沉积构造的响应机理为主线，以构造几何定量解析、定量地震地貌学和储层构型相结合的研究方法为桥梁，确定泥岩底辟区同沉积构造的空间结构样式和几何特征参数，构建不同构造单元周围海底水道储层构型系列定量模式，进而探索海底水道定量控制参数与同沉积构造几何特征参数之间的耦合和关联，揭示海底水道储层构型对泥岩底辟区同沉积构造的响应机理。本项研究所获认识将有助于增强深海沉积-构造变形交互作用的理解，并对水道油气藏的高效开发和提高采收率具有重要指导意义。

与同沉积构造有关的海底水道是深海油气藏勘探的主要目标，弄清海底水道储层构型对同沉积构造的响应机理是解决深海水道油藏高效开发问题的关键理论基础。本项目以浅层高频地震信息为原型，利用构造几何定量解析、定量地震地貌学和储层构型相结合的研究方法，揭示海底水道储层构型对泥岩底辟区同沉积构造的响应机理。取得了如下新结果和认识：①系统提出了海底水道沉积构型界面十一级划分方案，1-9级为油气开发级次，10-11级为勘探级次，这不仅为地面与地下、现代与古代水道沉积的类比提供了理论依据，而且为深水水道油气藏不同尺度储层非均质解析提供了地质依据。②创新提出了基于岩相成因类型的深海水道分类方案，其根据不同重力流成因岩相充填的百分比作为界限，对不同水道类型进行了明确定义，具有更好的适用性与可操控性，对于深水水道储层预测及储层质量评价具有重要的实际意义。③发现了深海水道内部一个特殊的沉积单元-凹岸坝，可成为潜在的、储集性能较好的油气储集体。④揭示了复合水道弯曲段内部单一水道的迁移受控两大因素，即底辟构造活动和早期沉积地貌；相比较弯曲段的幅度和曲率，水道侧向迁移距离对两个控制因素更敏感；底辟构造控制的复合水道弯曲段，其内部单一水道的侧向迁移速率往往较高，弯曲拐点处水道间隔较大，弯曲幅度一般变化不大，但底辟构造抬升有时可使得弯曲段水道曲率逐渐减低，甚至发生截弯取直现象；相反，早期沉积地貌控制的复合水道弯曲段，受早期废弃水道或天然堤的限制，其内部单一水道间的侧向迁移速率相对低，弯曲拐点处水道间隔较小。