摘要:
高分辨率层序地层为建立高分辨的年代地层格架提供了一种有效的方法。港东油田二区一断块的储油层段主要为明化镇组下段曲流河沉积,通过运用沉积基准面原理对研究区内岩芯、测井资料的综合分析,识别出了曲流河沉积短期、中期地层旋回及其特征,短期地层旋回可能主要为河流作用形成的自旋回,无法确定与基准面变化的关系;中期地层旋回则完全是由沉积基准面变化形成,由不同类型的短期地层旋回构成,并发现不同的短期旋回出现在中期基准面旋回的不同位置,相同的微相在中期基准面旋回的不同位置具有不同的结构特征,弄清了中期基准面对作为主要储层的河道砂体的侧向连通性和内部非均质性的控制作用。根据这些特征,建立了工区二维高分辨率地层对比格架,并在此基础上对工区的储层分隔间进行了预测。
Abstract:
Gangdong oil field,claiming a history of 30 years, locates in Huanghua depressio n of Gulf of Bohai basin. Reservoirs of the oil field are to the fluvial facies deposits, and is extremely heterogeneous and layered. The reservoir mostly consists of small striped channel deposits interbedded with flood-plain. It is v ery difficult to correlate reservoirs. High-resolution sequence stratigraphic an alysis can serve directly to high-resolution stratigraphic framework. Fir st fault block, the second area of Gangdong oil fields is selected as the study area. Based on the principle of base-level cycles, two scales of stratigraphic c ycles (short-and intermediate-term) are recognized through the combination of cores and logs data in the area. The short-term stratigraphic cycles, which may be not relate to base-level cycle, are the result of channel avulsion autocyclic process, Five type of channel avulsion auto-cycles are identified. The intermed iate-term stratigraphic cycles correspond to change of base-level cycle, and dif ferent types of the short-term cycles occur in different position of the interme diate-term base-level cycle. The same microfacies has different architecture in different position of the base-level cycle. The base-level cycle directly contro ll the channel reservoir geometry, Within an intermediate-term base-level cycl e, during periods of low accommodation, channel deposits is mostly lateral agg radation, and channel reservoirs superpose and connecte each other. As accomm odation increased, channel reservoirs become progressively isolated within flood -plain mudstone. According to that characterization, high-resolution sequence st ratigraphic framework has been established based on intermediate-term base-level cycle, and using the high-resolution correlation to identify reservoir continui ty and heterogeneities that could divide reservoirs into fluid flow compartments and are the most important factots in controlling the rates and pathways of flu id flow through reservoir.
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