Sedimentary Characteristics and Model of Permian System in KeBai Area in the Northwestern Margin of Jungar Basin
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摘要: 准噶尔盆地西北缘二叠系是重要的产油层和储集层，通过岩心观察、薄片分析，结合测井和录井资料，对西北缘克百断裂下盘二叠系砂砾岩的沉积环境和沉积特征进行了深入研究。研究表明，该区砂砾岩既有水上冲积扇沉积环境沉积的，也有水下扇三角洲前缘沉积环境形成的。前者主要为棕褐色、泥质杂基含量高、分选和磨圆差，储层物性相对较差；后者经过了稳定水流的淘洗，杂基含量少，钙质或沸石类胶结发育，分选性和磨圆度也较高，其物性条件也明显较好。并据此建立了研究区冲积扇与扇三角洲有机结合的沉积模式，该模式突出了湖岸线的重要性，同时模糊冲积扇与扇三角洲之间的界限。并对冲积扇与扇三角洲各亚相的岩性特征、沉积结构和沉积序列进行了归纳和总结，为该区寻找二叠系优质储层提供借鉴和思路。Abstract: Permian is the important oil layer and reservoir in the northwestern margin of Junggar Basin. By means of observing cores, analyzing sections and well logging data, we studied on the sedimentary environment and characteristics of the Permian glutenite which stored in the downdip block of KeBai fault in the northwestern margin of Junggar Basin. The result shows that some glutenites pertained to alluvial fan deposit, the other pertained to front fan delta deposit. The former was brown, wealthy of argillaceous matrix, poorly rounded and sorted and poor reservoir physical property; the later was poor of argillaceous matrix, Supermature calcitic or zeolitic cementation, well rounded and sorted with good reservoir physical property. So, we have established the combined sedimentation model of alluvial fan and delta fan. This model emphasized the importance of lake strandline and deemphasized the boundary of alluvial fan and delta fan. We summarized the lithologic characteristics and depositional texture and sequence of each subfacies of alluvial fan, and delta fan and provided the ideas of enplorating the Permian high quality reservoirs in the northwestern margin of Junggar Basin.
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Key words:
- Junggar Basin
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