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通过野外剖面观察、钻井岩心描述、薄片鉴定和扫描电镜分析,确定准噶尔盆地滴西地区石炭系火山岩储层的岩石类型主要以酸性的流纹岩和英安岩、中—基性的玄武岩和安山岩及火山角砾岩为主。1酸性的流纹岩和英安岩储层多发育于构造中低部位,遭受溶蚀作用强烈,在风化淋滤和构造埋藏阶段发育形成次生孔隙,但由于成岩早期原生气孔不发育,平均孔隙度仅有8.0%,最大孔隙度为13.5%,油气聚集性能较差;2中—基性的玄武岩和安山岩储层主要分布于火山口附近,与火山爆发的规模密切相关,原生孔隙形成于成岩阶段早期,次生孔隙发育于风化淋滤和溶蚀改造阶段,次生裂隙发育于构造埋藏阶段,平均孔隙度为9.2%,最大孔隙度为21.9%,是滴西地区较为优质的储层类型;3火山角砾岩储层具有与沉积岩相同的成岩特征,同时又具有火山岩的矿物组成,埋藏过程中刚性组分可以保持原生孔隙不受压实作用影响,同时因为其脆性特征又使其具有受力易断裂特征,内部裂隙发育。火山角砾岩发育于构造高部位,受淋滤作用时间较长,且特有的原始孔—缝组合也更易于受淡水或地下水淋滤,形成次生溶蚀孔隙。因此,风化淋滤阶段对火山角砾岩储层的物性改善明显,是滴西地区最优质的储层类型。
Through the field profile observation, drilling core description, sheet identification and scanning electron microscopy analysis, it is determined that the rock types of the Carboniferous volcanic reservoirs in the Xixi area of the Junggar Basin mainly consist of acidic rhyolite and dacite, medium-basal basalt and andesite, Volcanic breccia-based. 1 acidic rhyolite and dacite reservoirs mostly develop in the middle and lower parts of the structure and are strongly eroding. Secondary pores develop during weathering, leaching and tectonic burial. However, due to the undeveloped primary pores in the early diagenesis, the average porosity Only 8.0%, the maximum porosity is 13.5%, and the hydrocarbon accumulation performance is poor. 2 Basal basalt and andesite reservoirs are mainly distributed near the crater, which are closely related to the volcanic eruption scale. The primary porosity is formed in the diagenetic stage In the early stage, the secondary porosity developed in the stage of weathering, leaching and dissolution. The secondary fissure developed in the tectonic burial stage. The average porosity was 9.2% and the maximum porosity was 21.9% The volcanic breccia reservoirs have the same diagenesis characteristics as the sedimentary rocks and at the same time have the volcanic mineral composition. During the burial, the rigid components can keep the primary pores unaffected by the compaction, and at the same time, they have the force due to their brittle characteristics Fracture characteristics, the development of internal cracks. Volcanic breccias develop in high tectonic parts and leach for a long time, and the unique primary pore-seam assemblage is also more easily leached by freshwater or groundwater to form secondary dissolution pores. Therefore, the weathering and leaching phase has obvious improvement on the physical properties of volcanic breccia reservoirs, which is the best reservoir type in the drop Xi region.