准噶尔盆地中拐地区上乌尔禾组富火山碎屑砂砾岩储层的古环境及储层机理研究

通过准噶尔盆地中拐地区二叠系上乌尔禾组的岩石矿物学特征、元素地球化学特征、沉积环境特征、物性特征、成岩作用特征等综合分析，研究了该区富火山碎屑砂砾岩储层的成因机理。结果表明，研究区乌尔禾组古气候总体较为稳定，为温暖湿润的气候，丰富的降水使上乌尔禾组发育多套厚层砂砾岩扇三角洲沉积体系，大量的火山碎屑在流域内湿润的气候条件下发生化学风化，并被富氧淡水携带入湖，水解释放大量的阳离子，使得上乌尔禾组时期湖盆水体环境为咸水的氧化条件。火山碎屑沉积埋藏后也为后期成岩作用提供了碱性的成岩流体环境以及自生矿物形成的物质基础。该区上乌尔禾组储层物性受到沉积环境和成岩作用的双重控制，埋深较浅的扇三角洲前缘水下分流河道微相的砂砾岩为研究区的主要目的储层，其储集空间主要为剩余粒间孔，以及长石、火山碎屑等溶蚀孔隙。

Study of the Paleoenvironment and Reservoir Mechanism for Volcanic Rich Clastic Reservoirs in the Upper Urho Formation in the Zhongguai Region,Junggar Basin

Based on a comprehensive analysis of petrological and mineralogical features, elemental geochemical, sedimentary environment, physical property, and diagenesis characteristics of the Permian Upper Urho Formation in the Zhongguai area of the Junggar Basin were studied, as was the formation mechanism of glutenite reservoirs layers, which were rich in volcaniclastics in this area. The results show that the palaeoclimate of the Urho Formation in the study area was warm, humid, and generally stable. The abundant precipitation developed multiple sets of thick?grained conglomerate fan delta deposition systems in the Upper Urho Formation. Under the humid climate, chemical weathering occurs, and sediment was carried into the lake by oxygen?enriched fresh water. Hydrolysis releases a large amount of cations, making the lake basin water environment in the Upper Urho Formation period experience salt water oxidation conditions. A large amount of volcanic debris also provided a basic diagenetic fluid environment and material basis for the formation of authigenic minerals for later diagenesis. The physical properties of the Upper Urho Formation reservoir in this area were controlled by the sedimentary environment and diagenesis. The shallow?buried fan delta front submarine distributary channel microfacies gravel is the main target reservoir in the study area, and the space mainly consists of the remaining intergranular pores and dissolved pores, such as feldspar and volcanic debris.