Karst geomorphological characteristics and formation mechanisms of Maokou Formation in Jianyang-Ziyang area
The Maokou Formation in Sichuan Basin is a difficult and key stratigraphic system for oil and gas exploration.Recently,drilling was carried out around the fault solution of the Maokou Formation in the southern Sichuan area,achieving significant breakthroughs and demon-strating the important significance of karst processes in the reservoir transformation of the Maokou Formation.However,there was a lack re-search on the development of karst reservoirs in the Jianyang-Ziyang region,hindering oil and gas exploration within the area.Based on log-ging,seismic data,and elemental geochemistry,an analysis was conducted on the Maokou Formation in the Jianyang-Ziyang area to clarify the distribution of dominant karst landforms at the top of the Maokou Formation.The results indicate that there are tubular karst channels devel-oped at the top of the Maokou Formation in the area,and there are a large number of immobile elements such as Zr,Ti,Th in the carbonate rocks at the top,indicating the existence of an unconformity surface at the top of the Maokou Formation.Above the unconformity surface lies a thick layer of basalt.The residual thickness of the Maokou Formation characterized by seismic profiles and logging data is divided into karst depressions,karst slopes,and karst platforms,with karst slopes being the dominant reservoir development zone.The formation of karst geomor-phology in Jianyang area is closely related to the formation uplift,exposure and dissolution before Emei Mountain basalt eruption.This study can provide a basis for the prediction of Maokou Formation carbonate karst reservoir in Jianyang area.
karst slopebasaltweathered crustMaokou FormationJianyang area
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