Basin-Floor Fans in the North Sea: Sequence Stratigraphic Models vs. Sedimentary Facies
Basin-Floor Fans in the North Sea: Sequence Stratigraphic Models vs. Sedimentary Facies
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DOI：
10.1306/522b440b-1727-11d7-8645000102c1865d
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发表时间：
1995-04
期刊：
影响因子：
3.5
通讯作者：
G. Shanmugam;R. Bloch;S. Mitchell;G. W. J. Beamish;R. Hodgkinson;J. Damuth;T. Straume;S. E. Syvertsen;K. Shields
中科院分区：
文献类型：
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作者：
G. Shanmugam;R. Bloch;S. Mitchell;G. W. J. Beamish;R. Hodgkinson;J. Damuth;T. Straume;S. E. Syvertsen;K. Shields
对北海及邻近地区 10 个不同地区或油田的 50 口井取芯的古近纪和白垩系深水砂岩储层近 12,000 英尺（3658 m）常规岩心的检查表明，这些储层主要由块体输送沉积物组成，主要是砂质滑塌和砂质碎屑流。经典浊积岩极其罕见，占所有岩心的比例不到 1%。表明滑坡和泥石流起源的沉积特征包括具有尖锐上部接触面的砂单元；塌陷褶皱；不一致的、陡峭的倾斜层（高达 60°）；滑翔机；剪切带；角砾状碎屑；碎屑注射；漂浮的泥岩碎屑；平面碎屑织物；碎屑逆分级；和中高基质含量（5-30%）。许多岩心储层要么先前被解释为盆底扇，要么表现出地震（例如，丘状形式）和测井特征（例如，块状图案）和地层关系（例如，下重叠到层序边界上），表明层序地层框架内的盆地扇。该模型预测盆底扇主要由富含沙子的浊积岩组成，具有横向广泛的片状几何形状。然而，通过几个盆底扇（包括 Gryphon-Forth、Frigg 和 Faeroe 地区）用地震和电缆测井特征对我们长（400-700 英尺）岩心中的沉积相进行校准表明，这些特征实际上几乎完全由主要由滑塌和碎屑流组成的质量输送沉积物组成。将泥石流等物质输送过程的沉积物与浊流沉积物区分开来，对于预测储层几何形状具有重要意义。具有塑性流动流变性的泥石流可以形成不连续、不连贯的砂体，与流体浊流沉积物相比，这些砂体更难描绘，开发起来也更不经济，流体浊流沉积物可能产生更多横向连续、相互连接的砂体。因此，我们的核心研究强调了深水沉积系统的复杂性，并表明模型驱动的遥感数据（即地震和电缆测井）解释以预测特定沉积相和沉积特征应谨慎进行。常规岩心的过程沉积学解释通常对于确定储层砂的真实来源和分布至关重要。
Examination of nearly 12,000 ft (3658 m) of conventional core from Paleogene and Cretaceous deep-water sandstone reservoirs cored in 50 wells in 10 different areas or fields in the North Sea and adjacent regions reveals that these reservoirs are predominantly composed of mass-transport deposits, mainly sandy slumps and sandy debris flows. Classic turbidites are extremely rare and comprise less than 1% of all cores. Sedimentary features indicating slump and debris-flow origin include sand units with sharp upper contacts; slump folds; discordant, steeply dipping layers (up to 60°); glide planes; shear zones; brecciated clasts; clastic injections; floating mudstone clasts; planar clast fabric; inverse grading of clasts; and moderate-to-high matrix content (5-30%). Many f the cored reservoirs either have been previously interpreted as basin-floor fans or exhibit seismic (e.g., mounded forms) and wireline-log signatures (e.g., blocky motif) and stratal relationships (e.g., downlap onto sequence boundary) indicating basin-floor fans within a sequence stratigraphic framework. This model predicts that basin-floor fans are predominantly composed of sand-rich turbidites with laterally extensive, sheetlike geometries. However, calibration of sedimentary facies in our long (400-700 ft) cores with seismic and wireline-log signatures through several of these basin-floor fans (including the Gryphon-Forth, Frigg, and Faeroe areas) shows that these features are actually composed almost exclusively of mass-transport deposits consisting mainly of slumps and debris flo s. Distinguishing deposits of mass-transport processes, such as debris flows, from those of turbidity currents has important implications for predicting reservoir geometry. Debris flows, which have plastic flow rheology, can form discontinuous, disconnected sand bodies that are harder to delineate and less economical to develop than deposits of fluidal turbidity currents, which potentially produce more laterally continuous, interconnected sand bodies. Our core studies thus underscore the complexities of deep-water depositional systems and indicate that model-driven interpretation of remotely sensed data (i.e., seismic and wireline logs) to predict specific sedimentary facies and depositional features should proceed with caution. Process sedimentological interpretation of conventional cor is commonly critical for determining the true origin and distribution of reservoir sands.