鄂尔多斯盆地红井子地区长9油层组层序分析与砂体预测

根据岩心观察、铸体薄片、岩石学特征、沉积构造、古生物标志、矿物学特征及地球化学分析成果的分布分析,结合测井解释成果对红井子地区长9油层组高分辨层序地层学及砂体平面展布特征行了系统研究。发现该区长9油层组时期为砂体具毯状展布特征的典型浅水三角洲沉积体系。高分辨率层序地层学研究发现,长9油层组可划分为上部长91和下部长92两个湖侵-湖退旋回,通过基准面旋回结构分析,将该地区长9油层组确定为1个大的区域性湖侵序列,2个次级的湖侵-湖退旋回,划分出1个长期旋回层序,2个对应于长91及长92油层的中期旋回层序,4个对应于小层的、包括湖侵和湖退沉积体系域在内的基准面升、降相域。同时建立了长9油层组等时地层格架,对小层砂体进行了的追踪对比和预测。

High resolution sequence analysis and sand body prediction of Chang 9 oil set in Hongjingzi area, Ordos Basin

Abstract: Based on core observation, casting thin sections, petrological features, sedimentary structures, paleontology marks, and mineralogical and geochemical analysis, combined with well log interpretation results of Chang 9 oil set of high resolution sequence stratigraphy and the plane distribution of sand body in Hongjingzi area, the authors have found that, in the period of Chang 9 oil set, this area developed a typical shallow water delta depositional system in which the sand body showed blanket distribution characteristics. High resolution sequence stratigraphy studies show that Chang 9 oil set can be divided into two lake transgressive-retrogressive cycles, i.e., the upper Chang 91 and the lower Chang 92. The base level cycle structure analysis revealed that Chang 9 oil set in this area can be identified as being composed of a large regional lake transgressive sequence and two secondary lake transgressive-retrogressive cycles, and can be divided into a long-term cycle sequence, two middle-term cycle sequences corresponding to the Chang 91 and Chang 92 oil set respectively, and four base-level rising and falling phases corresponding to small layers, including lake transgressive-retrogressive depositional systems tracts. In addition, the authors set up the isochronous stratigraphic framework of Chang 9 oil set, and carried out the tracking correlation and prediction of small layers sand bodies.