姬塬油田长4＋5砂岩储层孔隙类型与成岩作用

Pores Type and Diagenesis in the Chang 4+5 Sandstone Reservoirs of the Jiyuan Oilfield

通过常规物性、岩石及铸体薄片、重矿物、X射线衍射、扫描电镜等多项测试方法,对鄂尔多斯盆地姬塬油田长4+5含油砂体的岩石学特征、成岩作用、储集类型进行了分析和研究。长4+5储层孔隙主要以粒间孔和长石溶孔为主,粒间溶孔次之,孔隙组合一般以粒间孔和溶孔-粒间孔为主。本区破坏性成岩作用包括机械压实作用、石英及长石的次生加大、碳酸盐胶结作用等,其中压实作用是造成本区砂岩原生孔隙大量丧失的主要原因。建设性成岩作用为溶蚀作用、绿泥石粘土膜形成作用,但溶蚀作用产生的次生孔隙对储层物性的改善不足。

The petrologic characteristics, diagenesis and pore types in Chang 4＋ 5 reservoir of the Jiyuan oilfield in Ordos Basin are studied by varied methods, including examination of the normal physical properties, thin-section ＆ casting thin-section, heavy minerals, X-ray diffraction and SEM analysis. The dominating pore type of Chang 4＋5 reservoirs is intergranular pore and feldspar-dissolved pore, the subordinate is the dissolved intergranular pore. Assembly of the pore types is usually intergranular pore and dissolved pore-granular pore. The constructive diagenesis in Chang 4 ＋ 5 reservoir is compaction, secondary enlargement of quartz and feldspar, cementation of carbonate mineral, etc. It is the compaction that reduces the primary pore space in Chang 4＋5 reservoirs. The destructive diagenesis that keeps or enlarges pore space is dissolution, clay membrane of chlorite. It is insufficient for dissolution to improve the pore space.