塔南凹陷铜钵庙组火山碎屑岩成岩作用

Diagenesis of Tongbomiao Volcanoclastic Rocks in Tanan Sag in Hailaer-Tamuchag Basin,Inner Mongolia

综合利用岩心、薄片、扫描电镜等资料,对塔南凹陷铜钵庙组火山碎屑岩的岩石学特征、成岩作用及其对储集层的影响进行了研究。结果表明,塔南凹陷铜钵庙组火山碎屑岩主要有熔结凝灰岩、凝灰岩、沉凝灰岩、凝灰质砂岩和凝灰质砾岩;除发育压实、胶结和溶解等成岩作用外,火山碎屑岩成岩特征与正常沉积碎屑岩相比具有特殊性,主要体现在熔结、脱玻化与重结晶作用上。熔结和脱玻化作用形成了大量次生孔隙,改善了火山碎屑岩储集层物性,微晶石英包壳的存在有利于原生粒间孔隙的保存;压实和碳酸盐胶结作用是导致储集层物性变差的主要因素。

The cores, thin-section and SEM data were used to research the diagenesis of volcaniclastic rocks and its effects on reservoir quality of Tongbomiao formation in Tanan sag in Inner Mongolia. The results show that the volcanielastic rocks of Tongbomiao formation mainly consist of ignimbrite, tuff, tuffites, tuffaceous sandstone and tuffaceous conglomerate. In addition to the compaction, cementation and dissolution, the diagenetic characteristics of the volcanoclastic rocks are of peculiar properties, compared with normally sedimentary elastic rocks, such as clinkering process, devitrification and reerystallization. The clinkering and devitrification processes result in abun- dant secondary pores which improve the physical property of the reservoir. The existence of microcrystalline quartz cladding is beneficial to the conservation of primary intergranular porosity. The compaction and the carbonate cementation are mainly factors to allow the reservoir quality to be poor.