Submarine fans: Characteristics, models, classification, and reservoir potential
Submarine fans: Characteristics, models, classification, and reservoir potential
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DOI：
10.1016/0012-8252(88)90064-5
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发表时间：
1988-02
影响因子：
12.1
通讯作者：
G. Shanmugam;R. J. Moiola
中科院分区：
文献类型：
--
作者：
G. Shanmugam;R. J. Moiola
海底扇层序是世界上重要的油气藏。海底扇层序可以从层厚趋势、浊积岩相组合、测井图案和地震反射剖面来解释。浊积岩主要产于河道和叶瓣（或席状砂）中，构成海底扇层序的主要部分。向上变薄和变厚的趋势分别表明河道和叶瓣沉积。堆积地震反射通常指示下扇沉积波瓣。从现代和古代扇、附着和分离波瓣、高效和低效系统以及横向和纵向扇的角度讨论扇模式。一般来说，沉积叶被认为是附属于补给河道。海底扇根据其构造环境可分为四种类型：（1）未成熟的被动边缘扇（北海型）;（2）成熟的被动边缘扇（大西洋型）;（3）活动边缘扇（太平洋型）;（4）混合设置扇。不成熟的被动边缘风扇（例如，Balder，North Sea）和主动边缘风扇（例如，海军，太平洋）通常是小，砂丰富，并拥有发育良好的叶片。成熟的被动边缘风扇（例如，亚马逊，大西洋）是大的，泥丰富，不发展典型的叶。然而，席状砂在成熟的被动边缘扇的下扇区是常见的。混合设置风扇显示大西洋类型的特征（例如，孟加拉、孟加拉湾）或太平洋型（奥里诺科河、加勒比海），或两者兼有。传统的通道波瓣模型可能不适用于与成熟被动边缘相关的扇体。海底扇体主要在主动边缘和被动边缘背景下的低海平面时期发育。因此，含油气扇层序一般与全球海平面低位有关。在大多数构造背景下，碎屑充填砂岩是潜在的储层。就含砂量、横向连续性和孔隙度发育而言，瓣状体表现出最有利的储层质量。低扇席状砂也可能成为良好的储层。成熟的被动边缘扇的富石英砂岩最有可能保存沉积孔隙，而活动边缘扇的岩屑砂岩可能不保存。
Submarine-fan sequences are important hydrocarbon reservoirs throughout the world. Submarine-fan sequences may be interpreted from bed-thickness trends, turbidite facies associations, log motifs, and seismic-reflection profiles. Turbidites occurring predominantly in channels and lobes (or sheet sands) constitute the major portion of submarine-fan sequences. Thinning- and thickening-upward trends are suggestive of channel and lobe deposition, respectively. Mounded seismic reflections are commonly indicative of lower-fan depositional lobes.Fan models are discussed in terms of modern and ancient fans, attached and detached lobes, highly efficient and poorly efficient systems, and transverse and longitudinal fans. In general, depositional lobes are considered to be attached to feeder channels. Submarine fans can be classified into four types based on their tectonic settings: (1) immature passive-margin fans (North Sea type); (2) mature passive-margin fans (Atlantic type); (3) active-margin fans (Pacific type); and (4) mixed-setting fans. Immature passive-margin fans (e.g., Balder, North Sea), and active-margin fans (e.g., Navy, Pacific Ocean) are usually small, sand-rich, and possess well developed lobes. Mature passive-margin fans (e.g., Amazon, Atlantic Ocean) are large, mud-rich, and do not develop typical lobes. However, sheet sands are common in the lower-fan regions of mature passive-margin fans. Mixed-setting fans display characteristics of either Atlantic type (e.g., Bengal, Bay of Bengal), or Pacific type (Orinoco, Caribbean), or both. Conventional channel-lobe models may not be applicable to fans associated with mature passive margins.Submarine fans develop primarily during periods of low sea level on both active- and passive-margin settings. Consequently, hydrocarbon-bearing fan sequences are associated generally with global lowstands of sea level. Channel-fill sandstones in most tectonic settings are potential reservoirs. Lobes exhibit the most favorable reservoir quality in terms of sand content, lateral continuity, and porosity development. Lower-fan sheet sands may also make good reservoirs. Quartz-rich sandstones of mature passive-margin fans are most likely to preserve depositional porosity, whereas lithic sandstones of active-margin fans may not.