彭松, 李珊珊, 胡德胜, 盖永浩, 李磊, 严恒. 北部湾涠西南凹陷斜阳斜坡早渐新世低位三角洲沉积及油气地质意义[J]. 海洋地质前沿, 2017, 33(10): 32-39. DOI: 10.16028/j.1009-2722.2017.10004
    引用本文: 彭松, 李珊珊, 胡德胜, 盖永浩, 李磊, 严恒. 北部湾涠西南凹陷斜阳斜坡早渐新世低位三角洲沉积及油气地质意义[J]. 海洋地质前沿, 2017, 33(10): 32-39. DOI: 10.16028/j.1009-2722.2017.10004
    PENG Song, LI Shanshan, HU Desheng, GAI Yonghao, LI Lei, YAN Heng. DEPOSITIONAL CHARACTERISTICS OF THE EARLY OLIGOCENE LOWSTAND DELTA IN XIEYANG SLOPE ZONE OF WEIXINAN DEPRESSION, BEIBUWAN BASIN AND THEIR PETROLEUM GEOLOGICAL SIGNIFICANCE[J]. Marine Geology Frontiers, 2017, 33(10): 32-39. DOI: 10.16028/j.1009-2722.2017.10004
    Citation: PENG Song, LI Shanshan, HU Desheng, GAI Yonghao, LI Lei, YAN Heng. DEPOSITIONAL CHARACTERISTICS OF THE EARLY OLIGOCENE LOWSTAND DELTA IN XIEYANG SLOPE ZONE OF WEIXINAN DEPRESSION, BEIBUWAN BASIN AND THEIR PETROLEUM GEOLOGICAL SIGNIFICANCE[J]. Marine Geology Frontiers, 2017, 33(10): 32-39. DOI: 10.16028/j.1009-2722.2017.10004

    北部湾涠西南凹陷斜阳斜坡早渐新世低位三角洲沉积及油气地质意义

    DEPOSITIONAL CHARACTERISTICS OF THE EARLY OLIGOCENE LOWSTAND DELTA IN XIEYANG SLOPE ZONE OF WEIXINAN DEPRESSION, BEIBUWAN BASIN AND THEIR PETROLEUM GEOLOGICAL SIGNIFICANCE

    • 摘要: 南海北部湾盆地涠西南凹陷下渐新统涠二段油气勘探程度相对较低,作为一套湖平面上升期形成的富泥地层系统,内幕薄砂体成因和展布规律较复杂。笔者从构造沉积充填演化史入手,开展内幕多期次基准面旋回变化的剖析,识别出上、中、下3个四级层序。其中中层序早期为砂岩集中发育层段,进一步分析和追踪落实,该套砂岩呈正韵律牵引流特征,具有多期叠置、水动力较强、自北向南进积的特点,推测为受盆缘一系列断阶强烈活动影响而在洼中—斜坡带稳定分布的大型低位三角洲砂体。由于其沉积背景及储盖组合类型与该区烃源和油气运聚条件配置较好,因此,预测涠二段中层序早期低位—海侵域应是研究区重要的勘探层系,尤其是来自东北方向的长源低位三角洲则更具有广阔的勘探前景。

       

      Abstract: The W2 Formation of Lower Oligocene in the Weixinan Depression of the Beibuwan Basin, South China Sea, is dominated by a set of muddy deposits formed during the period of lake level rising, in which the distribution of thin sand bodies is rather complicated. Petroleum exploration has so far remained in a relatively low stage due to lack of understanding of the origin and distribution of these sand bodies. This time, started from the study of tectonics and infilling history, we reconstructed the cyclic changes of base levels. And three 4th-level sequences, including the upper, the middle, and the lower sequences, are established. Sandstones are mainly concentrated in a positive rhythmic manner in the early stage of the middle sequence. They are the superimposed deposits of traction load formed under stronger water dynamic, and prograded from north to south. Based on the analysis of the tectonic and landform framework, we can find out that it was a very stable large-scale lowstand deltaic system no matter in the sag or on the slope. The deltaic bodies were affected severely by faulted terraces along the edge of the basin. It is believed that the specific depositional background and the types and characteristics of the reservoir and cover match well with the formation of source rock and the migration and accumulation of oil and gas in this area. A lowstand and transgressive system tract is then put forward for the first time for the deposits formed in the early period of the middle sequence of the W2 Formation. It should be a very important exploration target in the future.

       

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