Abstract: Lithology of Jiulaodong Formation in Lower Cambrian, Sichuan Basin is mainly dark shale mixed with siltsone and fine sandstone. In particular, the western part of the Basin which features in big thickness, abundant organic matter and high gas generating intensity has always been regarded as a good source bed. In recent years, due to the introduction of the concept of shale gas, people began to realize that shale was not only oil source bed, but also reservoir, involving the participation of siltstone, fine sandstone and even interbedded sand, which could make the generated gas accumulate and form reservoir at source bed. Based on previous research on clay shale of Jiulaodong Formation, the author further studied the formation and evolution, migration and reservoir formation of natural gas here, and believed that the block favorable for exploration was mainly Block Weiyuan of which the gas generating intensity reached 23 billion cubic meters per square kilometer, the Deying Formation of Sinian system was also a source bed and supplied natural gas continuously, and the mud shale of Ordovician -Silurian was sealed well. Second is Block Nanjiang located at the border of Sichuan and Shaanxi, with the intensity of gas generation between 3 and 6 billion cubic meters per square kilometer. Rock of Jiulaodong Formation has shown in the block, which features in shallow burial depth and low cost. It does not only save labor power, material resources and time, but also fast to be verified.

Key words: Sichuan Basin, Lower Cambrian, Jiulaodong Formation, shale gas, exploration