海拉尔盆地贝尔凹陷铜体庙组-南屯组储层次生孔隙成因及意义

海拉尔盆地贝尔凹陷白垩系南屯组和铜体庙组凝灰质砂岩、凝灰质泥岩、沉凝灰岩和凝灰岩储层是该区主要产层。油气储集空间以次生孔隙为主。大量碱性矿物组合如柯绿泥石、钠板石、碳钠铝石、方沸石、绿磷石、铈褐帘石、铁绿泥石等的存在,证明发生了大规模碱性溶解和交代作用。晶屑、玻屑、长石和粘土等填隙物均发生不同程度的溶解现象。研究表明,次生孔隙是凝灰质储层大规模碱交代作用的结果,预示盆地深部存在油气储集空间并富集油气。

THE CAUSES AND SIGNIFICANCE OF SECONDARY POROSITY OF NANTUN AND TONGTIMIAO FORMATION IN BEIER DEPRESSION,HAILAR BASIN

The tuffaceous reservoir is the major production layer of Beier Depression in Hailar Basin, which includes tuffaceous sandstone, tuffaceous mudstone, sedimentary tuff and tuff reservoirs in Nantun and Tongtimiao Formation of Cretaceous. There are a large number of standard type alkaline mineral assemblages in the reservoir, such as corrensite, allevardite, dawsonite, analcime, seladonit, cerium allanite, daphnite, etc. These mineral assemblages prove that extensive alkali dissolution and metasomatism occurred with the formation of secondary pores. The Crystal fragment, vitroclastic fragment, feldspar and clay fillings dissolve to varying degrees.The researches suggest that large-scale alkali metasomatism leads to the formation of secondary porosity.