Abstract: Drilling and exploration show that favorable reef-pore and karst-cave reservoirs developed in Ordovician of the platform margin belt in northern Tianhuan area, Ordos Basin. However, it is faced with such difficulties as complicated reservoir-forming conditions, poor seismic inside imaging, and strong reservoir heterogeneity. In order to open up new areas of exploration, this paper focuses on static correction, multi-domain denoising and prestack migration and other processing techniques to improve the Ordovician inside imaging accuracy. Seismic reflection pattern classification and attribute analysis techniques are enhanced, and the direct gas detection method about prestack carbonate reservoirs prediction is explored and applied, based on the study on favorable sedimentary facies belt. 1218 square kilometers of favorable reservoir development areas are evaluated comprehensively. New discovery is made in Kelimoli Formation of one exploration well confirms broad exploration prospects in the area once again

Key words: platform margin belt, reef pore, karst cave, inside imaging, heterogeneity, facies, favorable reservoir