鄂尔多斯盆地下古生界三山子白云岩体成因及储集性

鄂尔多斯盆地下古生界三山子白云岩体是一个由多期白云岩化和多种机理叠加改造的“穿时”白云岩体。在该岩体中可识别出两种白云岩化作用的环境和 7种白云岩化作用的类型。中粗晶白云岩、残余颗粒白云岩、细晶白云岩和灰质白云岩为本区最主要的储集岩。本区的储集空间丰富多样 ,溶孔、溶缝和缝合线溶孔等次生溶蚀孔隙是最主要的储集空间。该岩体有上、下两套储集体。上部储集体位于岩体顶部 ,储集性能好 ,其形成与古岩溶有关 ;下部储集体位于岩体的中下部 ,储集性能稍差 ,其形成与埋藏成岩作用有关。

ORIGIN AND RESERVOIR OF SANSHANZI DOLOMITE IN LOWER PALEOZOIC OF ORDOS BASIN

Sanshanzi dolomite of lower Paleozoic in Ordos basin is a diachronous compound dolomite body resulted from multiplex dolomization and multimechanism. Two dolomitization environments and seven dolomitization types are recognized. Middle\|coarse crystallized dolomite, residual grain dolomite, fine crystallized dolomite and lime\|dolomite are the important reservoir rocks in this area, and various reservoir spaces are developed. Solution pore, solution fissure and solution stylolite are the main reservoir spaces. Two reservoir rock bodies are developed in Sanshanzi dolomite. The upper reservoir rock body has a good reservoir property, and its forming is related to paleokarst. The reservoir property of lower reservoir rock body is worse than that of the upper body. The forming of lower reservoir concerns with the buried diagenesis.