刘英辉,蔡华,段冬平,等. 西湖凹陷平湖地区平湖组海侵体系域潮控三角洲-潮坪沉积特征及模式[J]. 海洋地质前沿,2022,38(1):33-40. DOI: 10.16028/j.1009-2722.2021.147
    引用本文: 刘英辉,蔡华,段冬平,等. 西湖凹陷平湖地区平湖组海侵体系域潮控三角洲-潮坪沉积特征及模式[J]. 海洋地质前沿,2022,38(1):33-40. DOI: 10.16028/j.1009-2722.2021.147
    LIU Yinghui, CAI Hua, DUAN Dongping, et al. The sedimentary characteristics of tidal delta and tidal flat in transgressive system tract of Pinghu Formation in Pinghu area, Xihu Sag[J]. Marine Geology Frontiers, 2022, 38(1): 33-40. DOI: 10.16028/j.1009-2722.2021.147
    Citation: LIU Yinghui, CAI Hua, DUAN Dongping, et al. The sedimentary characteristics of tidal delta and tidal flat in transgressive system tract of Pinghu Formation in Pinghu area, Xihu Sag[J]. Marine Geology Frontiers, 2022, 38(1): 33-40. DOI: 10.16028/j.1009-2722.2021.147

    西湖凹陷平湖地区平湖组海侵体系域潮控三角洲-潮坪沉积特征及模式

    The sedimentary characteristics of tidal delta and tidal flat in transgressive system tract of Pinghu Formation in Pinghu area, Xihu Sag

    • 摘要: 西湖凹陷始新统平湖组发育海陆过渡相沉积体系,岩性组合以三角洲-潮坪过渡相的砂、泥、煤薄互层为特征,由于沉积构造复杂、沉积微相类型多样,不同学者对沉积体系类型的认识一直存在争议,沉积体系及沉积模式的不确定性进一步制约了平湖组勘探开发的进程。基于平湖组岩芯、测井及分析化验资料,厘定了平湖组一、二段海侵域P7层典型相类型及相标志,采用地震沉积学地层切片方法提取了典型潮控三角洲地质形态,总结了西湖凹陷平湖组海侵域潮控三角洲典型沉积特征。研究区潮控三角洲砂体受潮汐改造作用强,发育典型双黏土层、再作用面、韵律层理、潮汐束等沉积构造;潮控三角洲主要发育三角洲前缘亚相,局部发育三角洲平原;海侵时期海平面快速上升,三角洲前缘受潮汐改造作用强,形成潮汐砂坝与潮汐水道为主的砂体,潮控三角洲侧边发育潮汐水道为主的砂体,潮汐砂坝与潮汐水道是有利的储层发育相带。研究区潮控三角洲沉积模式的建立为西湖凹陷平湖组滚动勘探开发指明方向。

       

      Abstract: The Pinghu Formation of Eocene in the Pinghu area of Xihu Sag is a set of transitional deposits consisting of alternative marine and non-marine depositional systems, which are characterized by thinly interbedded sand, mud and coal seams of deltaic-tidal transitional facies. Due to the complexity of sedimentary structures and the diversity of sedimentary microfacies, it has remained controversial among scholars about their origin and depositional systems. The uncertainty of sedimentary system restricted oil and gas exploration and development. Based on the core, logging and other analysis data from the Pinghu Formation, this paper defined the typical facies types and described their sedimentary characteristics for the P7 layer formed in the transgressive domain in the first and second stages of Pinghu Period. By means of seismic sedimentology, typical tidal delta is recognized and the depositional characteristics of tidal delta in the transgressive summarized. The sandbodies of tide-dominated delta are strongly reformed by tide. There develop such typical sedimentary structures as double clay layers, reaction surface, rhythmic bedding and tidal bundles. The tide dominated delta is mainly composed of the subfacies of inner and outer deltaic fronts, with deltaic plain locally. During the transgression period, the sea level rose rapidly, the delta front was strongly reworked by tide, and as the result, the sand bodies dominated by tidal bars and tidal channels were formed. It is believed that the establishment of tide-dominated deltaic sedimentary model in this paper may provided a clue and guideline for further exploration and development of oil and gas in the Pinghu Formation of the Xihu Sag.

       

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