Characteristics of Penecontemporaneous Karstification in Ordovician Majiagou Formation, Sulige Gas Field, Ordos Basin

Sulige gas field is the major gas-production area in Ordos basin.The carbonate of the Ordovician Majiagou formation is one of the most important target-strata for gas exploration. The karstification in the penecontemporaneous period has a significant constructive effect on the reservoir development of Majiagou formation,which is the most important contributor to the reservoir performance of the Lower Paleozoic in the study area.Based on the data of rock core and analysis data,this paper analyzes the high-frequency exposure characteristics and penecontemporaneous karstification in the study area,identified and summariedsix typical evidence of penecontemporaneous karstification.Combined with the geological background of the study area, the paper puts forward the process and development model of penecontemporaneous karst transformation, and further analyses that penecontemporaneous karst development is influenced by internal and external factors.It not only strengthens the understanding and recognition of karst types, but also enriches the paleokarst theory.