基于沉积时间单元的单砂体研究

以尕斯库勒油田N₁—N₂¹油藏Ⅱ号断层上盘Ⅶ砂组辫状河三角洲前缘亚相为例，探讨了基于小层规模的沉积时间单元划分、单砂体的含义与识别标志及构型模式。研究表明，根据自然伽马半幅点可以将小层细分为储层沉积时间单元、隔层沉积时间单元，并在储层沉积时间单元中识别出区域夹层。区域夹层与隔层沉积时间单元为泥岩沉积，储层沉积时间单元在横向上为砂泥岩间互沉积。在此基础上，提出了单砂体的完整概念，认为单砂体就是在三维空间被周围非渗透性的封隔层所包围的独立砂体。并指出了单砂体受沉积、构造及成岩三大因素控制，明确了在这三大因素控制下单砂体的识别标志，同时总结出了单砂体的基本构型模式。笔者成功地将这套研究方法应用于尕斯库勒油田Ⅶ—5小层，把原来小层级别的两个单砂体划分为沉积时间单元级别的17个单砂体，大大提高了单砂体的研究精度。

A Study on Single Sand Body Based on Sedimentary Time Unit

The braided river delta front subfacies of Ⅶ sand group in the hanging wall of fault N₁—N₂¹ reservoir of Gasikule Oilfield was chosen as the object of study. The division of sedimentary time unit, the meaning and identification mark of single sand body, and configuration mode are discussed. Based on the natural gamma half amplitude point, the subzone can be divided into reservoir sedimentary time unit, interlayer sedimentary time unit, and the regional interlayer within the reservoir sedimentary time unit. The sedimentary time units of the regional interlayer and interlayer are mainly composed of mudstone, and the sedimentary time unit of the reservoir majorly consists of laterally-connected sandstone and mudstone. The complete concept of a single sand body is first proposed based on the forgoing ideas. The single sand body, which is formed under the control of sedimentation, structure, and diagenesis, is supposed to be an independent unit surrounded by an impermeable barrier layer in three-dimensional space. The identification marks of a single sand body are clarified, and the basic configuration mode of a single sand body is also summarized in this study. The author has successfully applied this method to subzone Ⅶ—5 in the Gasikule Oilfield. The two single sand bodies of the subzone level are further divided into 17 single sand bodies of sedimentary time unit level, which greatly improves the research accuracy of a single sand body.