摘要:
综合应用高分辨率层序地层学理论和储层构型分析方法,以渤海湾盆地东营凹陷胜坨油田坨七断块沙二段下油组为例,研究长期基准面旋回背景下河口坝构型的演化规律。研究表明,研究区沙二段下油组对应一个长期基准面下降半旋回,并可进一步划分为8个中期基准面旋回及若干短期和超短期旋回。随着长期基准面的下降,河口坝越来越连片,坝体上分流河道的规模变大,延伸距离变长;在长期基准面下降早期,河口坝的侧向拼接样式以河口坝侧缘相互交错及河口坝之间被泥岩隔开样式居多,在长期基准面下降晚期,河口坝的侧向拼接样式主要为河口坝坝主体与侧缘的侧向叠置和河口坝侧缘与侧缘的侧向叠置;同时,随着长期基准面的下降,垂向上河口坝砂体间的连通性逐渐变好,河口坝前积的角度逐渐变小。长期基准面旋回对河口坝构型的控制主要通过可容空间的增减,沉积物供给速率的变化起作用。该研究对同类型油气田的砂体预测和剩余油分布的预测均具有重要的指导意义。
关键词:
-
胜坨油田 /
-
基准面旋回 /
-
构型 /
-
河口坝
Abstract:
High-resolution sequence stratigraphic theories and the architecture analysis method are synthetically applied to study controls of long-term base-level cycles on architecture of mouth bars by taking the lower Es2 Member in Fault-Block Tuo 7, Shengtuo oilfield as a case study. The results show that the bottom of Es2 Member of Tuo 7 Fault-Block in Shengtuo oilfield constitutes a long-term base-level decreasing semi-cycle which can be subdivided into 8 middle-term cycles, some short-term cycles and various super short-term cycles. During long-term base-level fall, continuity of mouth bars become better, scale of distributary channels on the bars become larger and extending distance of these channels become longer; At the early stage of long-term base-level fall, combination patterns between different mouth bars in the same period are mainly by means of one mouth bar's fringe staggers on the another or mouth bars are separated by inter bar mudstone, At the late stage of long-term base-level fall, combinations between different mouth bars in the same period are mainly by means of one bar's main part overlaps another bar's fringe or one bar's fringe overlaps another's; Meanwhile, during long-term base-level fall, mouth bars' vertical connectivity become better and dip angles become smaller. Long-term base-level cycle controls mouth bars' architecture mainly through regular change of accommodation and supply rate of sediments. This study has a potentially important significance in guiding prediction of sandstones and remaining oil's distribution in this type of oil and gas fields.