关键词: 成岩相, 成岩作用, 山³₂段砂岩, 子洲气田, 鄂尔多斯盆地

Abstract:

Diagenesis of tight sandstone reservoir is complicated and diagenetic facies presents apparent differences. Based on the testing data of physical property, cast section, SEM, X diffraction and high pressure mercury penetration, the diagenesis and diagenetic facies of Shan³₂ sandstone of Zizhou gas field in the eastern of Ordos basin are studied. The results show that lithology is dominated firstly by quartz sandstone, and lithic content increases from west to east. Intergranular pore, emposieu and intercrystal pore are the main pore types. Compaction and pressolution make the primary intergranular pore decrease heavily. Cementation lets the physical property become poor entirely, which has dual influence on reservoir interspaces. Quartz sandstone and lithic quartz sandstone are affected differently by dissolution. Quartz sandstone is corroded more easily. Shan³₂ sandstone of Zizhou gas field entered late diagenetic phase B, and partial indexes went into late diagenetic phase C according to the classification signs of diagenetic stage. Refer to qualitative and quantitative parameters, six diagenetic facies zones in the study area are classified. Weak compaction, quartz overgrowth intergranular pore-emposieu belts distributed in the thick sand body of underwater distributary channel are proposed to be the most favorable diagenetic facies. Weak compaction, quartz overgrowth intergranular pore-intercrystal pore phase and clay contamination filling intercrystal pore-emposieu phase take the second place. Distribution of diagenetic facies is controlled by deposition microfacies and detrital component.

Key words: diagenetic facies, diagenesis, Shan32 sandstone, Zizhou gas field, Ordos basin