Abstract: The QLB structure of northeast Sichuan province is located in the reef flat facies of the platform edge in the east of Guangwang trough. According to the analysis of drilling, logging and seismic data, the multi-parameter clustering analysis has been applied to predict the changes of the distribution and the thickness of the reefs. Firstly, using the statistical parameter information of logging curves and the information of well QLB101 and the seismic attributes from the traces beside the wells in reef sections, the attributes response characteristics of seismic profiles crossing the wells were established, and the parameter values of the sample well was identified. Then, the information of the reefs to be predicted was found out by picking up the sample values in a certain range. The prediction results show that the reef in QLB region is barrier reef with the thickness of above 60 m and the area of about 46.5km2. The reef target coordinate of QLB2 well was proposed according to the prediction results. The reef had been drilled in the predicted target center. The drilled reef is 55m in thickness and about 30 m in effective thickness. Industrial oil flow has been obtained in this well.