鄂尔多斯盆地张家山区长8储集层成岩作用及有利相带

通过岩心观察、偏光显微镜鉴定、扫描电镜、X衍射、高压压汞等手段,分析了鄂尔多斯盆地张家山地区长8储集层成岩作用特征及其对储集层的影响,进而对有利成岩相进行了研究。结果表明:研究区长8储集层砂岩的成岩作用处于中成岩A—B期,早期的压实作用和碳酸盐胶结作用使原始孔隙空间大量损失,是造成储集层物性较差的主要原因;早期绿泥石薄膜的发育使部分原生孔隙得以保存;溶蚀作用、交代作用和破裂作用使储集层的物性得到改善。根据成岩作用对物性的影响,划分出强压实相、碳酸盐胶结相、绿泥石薄膜剩余孔隙相、长石溶蚀相、长石溶蚀+绿泥石薄膜相和高岭石胶结相等6种成岩相带,优质储集层与成岩相密切相关,长石溶蚀+绿泥石薄膜相的砂体物性、含油性最好,是研究区长8储集层石油最富集的成岩相带,绿泥石薄膜相次之。

Diagenesis and Favorable Facies of Chang-8 Reservoir in Zhangjiashan Area in Ordos Basin

By means of core observation,polarization microscope,SEM,X-ray diffraction,mercury injection,the diagenesis and impact on Chang-8 sandstone reservoir in Zhangjiashan area in Ordos basin were analyzed,and then the favorable facies in it was studied.The results show that its diagenesis was in A-B stage,in which the early compaction and carbonate cementation resulted in loss of great numbers of primary pores,which was the main reason for poor reservoir quality;the early chlorite growth protected some primary pores;dissolution,metasomatism and cataclasis improved the reservoir quality.Based on the impact of the diagenesis on reservoir quality,the sand body of Chang-8 reservoir is subdivided into six diagenetic facies: intensive compaction facies,carbonate cement facies,chlorite film remained pore facies,feldspathic solution facies,feldspathic solution-chlorite film remained pore facies and kaolinite cement facies.It is concluded that the premium reservoir is closely related to the diagenetic facies,and the feldspathic solution-chlorite film remained pore facies are the best in sand body quality and petroliferous property,being the most favorable diagenetic facies for oil enrichment in this area,the chlorite film remained pore facies is the secondary important one.