火山碎屑岩储层特征及控制因素 ——-以塔木察格盆地塔南凹陷铜钵庙组-南屯组为例

以塔木察格盆地塔南凹陷铜钵庙组-南屯组火山碎屑岩为例，结合岩石学观察、薄片鉴定、扫描电镜分析等技术手段，研究火山碎屑岩储层特征及其影响因素。综合研究认为: 火山碎屑岩岩石类型主要包括凝灰岩( 熔结凝灰岩) 、沉凝灰岩和凝灰质砂( 砾) 岩; 发育有原生孔隙、原生裂缝、次生孔隙、次生裂缝等4 类10 种储集空间，且以次生溶孔为主; 属于中低孔--特低渗型储层，横向上靠近洼陷边缘、接近构造高部位的孔隙度和渗透率较高，纵向上在1 900 ～ 2 100 m、2 600 ～ 2 900 m 处存在两个明显的异常高孔隙带; 储集性能受岩性岩相、构造运动、成岩作用和有机质热演化等因素影响，其中岩性岩相和成岩作用是影响储层储集性能的主要影响因素。

Reservoir characteristics and controlling factors of pyroclastic rocks of Tongbomiao Formation and Nantun Formation from Tanan Depression in Tamtsag Basin,Mongolia

Reservoir characteristics and controlling factors of pyroclastic rocks were researched by observation on rocks with slides and SEM，taken those from the Tongbomiao Formation and Nantun Formation in Tanan Depression of Tamtsag Basin as an example． The pyroclastic rocks are mainly composed of tuff ( flood tuff) ，sedimentary tuff and tuffaceous sandstone ( conglomerates) ． Pyroclastic reservoir spaces can be divided into four types: primary pores，primary cracks，secondary pores，secondary cracks，including 10 sub-types，dominated by secondary dissolved pores． The pyroclastic rocks belong to the reservoir with middle-low porosity and extra low permeability in type with approaching the edge of depression，the porosity and permeability become higher． Two abnormal high porosity belts are found at the locations of 1 900 m ～ 2 100 m and 2 600 m ～ 2 900 m． Reservoir qualities are affected by lithology and lithofacies，tectonic movement，diagenesis，thermal evolution of organic matter，etc． ，in which the main influence factors are lithology，lithofacies and diagenesis．