鄂尔多斯盆地乌兰格尔隆起南坡石炭-二叠系储层孔隙结构及成因

本文论述了鄂尔多斯盆地北部乌兰格尔隆起南坡石炭-二叠系储层的孔隙结构特征及其成因。认为孔隙结构不太理想,主要是比较细小的填隙物内与溶蚀粒内孔隙;毛管压力曲线以比较差的4、5类,特别是5类占优势。孔隙结构级别应属比较差的Ⅳ、Ⅴ两级。变差的主要原因与本区经受复杂强烈的成岩作用有关。在所划分的四个成岩阶段中,第一、二阶段的压实与充填交代使孔隙显著减小,而第三阶段的溶蚀作用并不发育,第四阶段又进一步充填。在论述孔隙结构相对较好地区与层段的同时,指出高岭石填隙物内晶间孔隙仍有可能成为有利的储集空间,应给以注意。

PORE TEXTURE AND ORIGIN OF CARBONIFEROUS-PERMIAN RESERVOIRS IN SOUTH SLOPE OF WULANGAR RISE IN ORDOS BASIN

The pore texture and origin of the Carboniferous-Permian reservoirs in the south slope of wulangar rise in the north part of Ordos Basin is studied by casting thin section,injecting mercury,SEM,etc..The result indicates that pore texture is not so good and the pores are mainly very small intra-interstitial materials and dissolved intragranular ones.The capillary pressure curves show dominatly type-4 and -5,especially type-5.Thepore texture therefore should be defined as grade 4 or grade 5.The reason caused the poorpore texture is related to the complicated and intensive diagenesis.Within 4 diagenesis stages,the compaction,filling and replacement in the first two stages greatly decreased the pore spaces,though there was dissolution in the third stage,they did not develop well and were filled again in the last stage.According to the fact that well No.Y17 has producedgas,the pores of the intra-interstitial kaolinite may still be available reserving spaces.