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北部湾盆地乌石凹陷东区流沙港组三段岩性相对复杂,沉积差异大,横向变化快,连通性差,深入研究流沙港组三段沉积物源和沉积特征对油气勘探开发具有一定的指导意义。在系统的岩心观察与精细描述基础上,结合测井、地震和分析化验资料,针对研究区流沙港组三段沉积物源、沉积相类型及展布特征展开研究。综合分析认为,流沙港组三段物源来自于北部高地势地区,发育相对近物源的水进型扇三角洲沉积,砂体厚度较大,相带窄,相变快,其中三角洲前缘可进一步划分为水下分流河道、河口坝、席状砂、分流间湾等4种沉积微相;在物源分析、井震约束的基础上,依据井震结合含砂率等值线,同时结合测井平面相、地震反射结构、地震构型信息等,综合绘制研究区沉积微相平面展布图,确定了研究区流沙港组三段“大前缘小平原”的沉积特征,并最终建立了该区扇三角洲沉积模式,为乌石凹陷东区流沙港组三段油气勘探开发和储量计算提供了借鉴。
The lithology of the third member of the Liushagang Formation in the eastern Wushi Sag of Beibuwan Basin is relatively complicated with large sedimentary differences and rapid horizontal changes. The connectivity is poor. Therefore, it is of guiding significance to study the sedimentary provenance and sedimentary features of the third member of the Liushagang Formation . Based on systematic observation and detailed description of the core, combined with well logging, seismic and analytical laboratory data, the sedimentary source and sedimentary facies types and distribution characteristics of the third member of the Liushishagang Formation in the study area are studied. According to a comprehensive analysis, the source rocks of the third member of the Liushagang Formation are from the high-lying northern area and have relatively shallow water-related fan delta deposits. The thickness of the sand body is large, the phase belt is narrow, and the phase transition is rapid. The front of the delta can be Further divided into four subfacies: underwater distributary channel, estuarine dam, sheet sand and shunt bay. On the basis of provenance analysis and well restraint, Logging plane facies, seismic reflection structure and seismic configuration information, the depositional facies of the sedimentary microfacies in the study area are comprehensively drawn, and the sedimentary characteristics of the “three large sections of the Liushagang Group” in the study area are determined Finally, the depositional pattern of fan delta in this area is established, which provides reference for oil and gas exploration and development and reserves calculation of the third member of the Liushagang Formation in the eastern Wushi Depression.