扇三角洲前缘储层构型精细解剖——以辽河油田曙2-6-6区块杜家台油层为例

Fine Anatomizing Reservoir Architecture of Fan-delta Front: A Case Study on Dujiatai Reservoir in Shu2-6-6 Block,Liaohe Oilfield

扇三角洲储层是一类重要的油气储层,其可动剩余油储量占我国碎屑岩储层可动剩余油储量的17.4%。目前国内关于扇三角洲储层,特别是扇三角洲前缘储层的构型研究甚少,难以满足此类油藏剩余油分布预测的需要。为此,以辽河油田曙2-6-6区块杜家台油层为例,应用岩心、测井和动态资料,分析了扇三角洲前缘储层构型单元的特征,明确了构型的分级系统,开展了复合砂体和单一砂体级次的构型解剖。研究表明:①研究区发育的储层构型单元包括辫状水道、河口坝和溢岸,不同构型单元形成的复合砂体存在3种平面分布样式。②复合砂体内部单一砂体的识别主要依据其垂向和侧向识别标志,其中垂向识别标志包括钙质夹层和泥质夹层2种,侧向识别标志包括曲线特征区域差异、砂体侧向叠置等6种。③不同类型单一砂体的规模分布存在差异,其中辫状水道厚度介于0.8～6.6m之间,宽度介于100～400m之间;河口坝厚度介于1.2～6m之间,宽度介于200～710m之间,2类砂体的宽厚之间均呈现较好的指数关系。最终,依据研究区储层构型的定性及定量解剖成果,建立了符合地质模式的三维构型模型,为寻找剩余油及挖潜提供了可靠的地质依据。

Fan-delta front reservoir is an important reservoir in China, whose movable residual oil reserves account for 17.4% of all movable residual oil reserves in clastic reservoir. At present,research on reservoir architecture of fan-delta front is few, especially the architecture of the fan-delta front reservoir. It is difficult to meet the demand on prediction of residual oil distribution in this type reservoir. Taking Dujiatai reservoir in the Shu2-6-6 block of Liaohe oilfield as an example,we analyzed the characteristics of different architecture elements of fan-delta front, determined the hierarchical system of architecture and anatomized the compound and single sandbodies using various data including cores, well logging and production performance data. The results show that braided channel, mouth bar and overflow as architecture elements are developed in the study area. The compound sandbody composed of different elements shows 3 kinds of distributional patterns. The recognition of single sandbody depends on the vertical and lateral symbols. The vertical symbols include muddy intercalations and calcareous intercalations. The lateral symbols include difference on elevation,lateral overlay between different single sandbodies and so on. Different types of single sandbody has differences in distribution and scale. The braided channel is 0.8 to 6.6 meters thick and 100 to 400 meters wide. The mouth bar is 1.2 to 6 meters thick and 200 to 710 meters wide. The width and thickness of two the types of sand bodies both show a typical exponential relationship. Finally, according to the qualitative and quantitative anatomizing achievements of reservoir architecture, three-dimensional reservoir architecture model is established precisely to find and produce remaining oil.