羌塘盆地中上侏罗统砂岩储集性特征

RESERVOIR CHARACTERS OF THE JURASSIC SANDSTONES IN QIANGTANG BASIN

在大量野外露头资料研究的基础上 ,运用岩石薄片、铸体薄片、扫描电镜、常规物性、毛细管压力曲线和图象分析等手段 ,对羌塘盆地侏罗系砂岩的孔渗性及孔隙结构等特征作了详细研究。孔隙类型主要为次生溶孔 ,偶见剩余原生粒间孔 ,它们基本上属于低孔低渗致密储集层 ,同时孔隙的微观结构较差。强烈的机械压实作用是导致砂岩孔隙结构变差的主要因素 ;早期碳酸盐胶结作用较弱 ,使得后期的溶解改造作用也较弱 ;这造成了砂岩的有效储集空间较差的结果。构造作用使得岩石中裂隙发育 ,提高了岩石孔渗性 ,极大地改善了岩石的储集性能 。

Based on the study of outcrop data,combined with the application of various analytical techniques,such as conventional analysis of the core, thin sections, casting sections, SEM,capillary pressure curve,pore permeability distribution and pattern analysis of pore structure,the property of the pore and permeability and pore structure of the Jurassic reservoir sandstone in Qiangtang basin is studied.The types of pore are mainly secondary solution pores with minor primary remains of intergranular pores and the reservoir is characterized by low porosity and permeability. The poorly developed pore texture of the sandstone is caused by strong compaction,early poor cementation of carbonate and late poor dissolution of carbonate.The situation is improved by deformation which creates the fissures,increases the permeability and improves the reserior capacity of sandstone in Qiangtang basin.