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

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

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。

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 transgressiveretrogressive cycles, i.e., the upper Chang 91 and the lower Chang 92. The base level cycle structure analysis revealed that Chang 9oil 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.