天然气勘探与开发2025，Vol.48Issue(2)：26-38,13.DOI:10.12055/gaskk.issn.1673-3177.2025.02.003
差异成岩作用对致密砂岩储集性能的影响
Impact of differential diagenesis on the reservoir quality of tight sandstone:An example from Chang 81 submember,Wuqi-Shunning area,Ordos Basin
摘要
Abstract
Being an important exploration target of tight oil in Ordos Basin,the eighth member of the Upper Triassic Yanchang Formation(Chang 8 Member)has been discovered from several super-giant oilfields in Jiyuan,Xifeng,Maling areas,suggesting great exploration potential.Therefore,the first submember of Chang 8 Member(Chang 81 submember)in Wuqi-Shunning area was taken as an example to discuss the distribution of effective tight sandstone reservoirs affected by both sedimentation and diagenesis in this basin.For Chang 81 reservoirs,the petrology,diagenesis and physical properties were studied through core observation,cast thin-section observation,scanning electron microscopy(SEM)and physical property analysis.In addition,the distribution of diagenetic facies belts was figured out,and some favorable zones were predicted for reservoir extension.Results show that(i)characterized by extremely low porosity and permeability,these Chang 81 reservoirs with intergranular pores and feldspar dissolved pores as the dominant reservoir space are dominated by fine-to medium-grained feldspathic sandstone and lithic feldspathic sandstone;(ii)dissolution is deemed as the main constructive diagenesis while both compaction and cementation as destructive one.This dissolution in Wuqi has slightly higher intensity than that in Shunning,whereas the compaction and cementation intensity in Wuqi evidently lower than that in Shunning;and(iii)five diagenetic facies can be divided in the study area in line with diagenetic minerals and diagenesis type and intensity,including carbonate+illite cemented tight facies,compaction-pressolution tight facies,authigenic clay+carbonate cemented facies,chlorite thin-film cementation+dissolution facies,and quartz-enlarged cementation+dissolution facies,among which the latter two are most favorable for reservoir extension.In conclusion,the central Wuqi-Shunning area is in favor of diagenetic facies and reservoir extension.关键词
鄂尔多斯盆地/三叠系上统延长组/致密砂岩/储集层/成岩作用/溶蚀作用Key words
Ordos Basin/Upper Triassic Yanchang Formation/Tight sandstone/Reservoir/Diagenesis/Dissolution引用本文复制引用
岳怀海,冯明友,刘小洪,肖文联,石坚,李月娥,曹娟..差异成岩作用对致密砂岩储集性能的影响[J].天然气勘探与开发,2025,48(2):26-38,13.基金项目
国家科技重大专项(编号:2017ZX05001001). （编号:2017ZX05001001）
