Abstract: Reservoirs have been discovered in the granite formation of the buried hill of Bongor Basin in Block H of Chad by CNPC International (Chad) Ltd. The granite formation of the buried hill of Bongor Basin has low formation pressure (fracture pressue 1.0) and well developed fractures, which can easily result in severe loss during drilling operation. In view of the advantages of UBD technology in improving discovery, increasing ROP, avoiding downhole troubles and protecting reservoirs, it was decided that UBD technology was used to drill the granite formation of the buried hills in Bongor Basin. This paper presents a preliminary UBD program based on the analysis of geological conditions and previous drilling in the granite formation in the buried hill of Bongor Basin, analyzes the trial test of two UBD wells, and makes suggestions for improving field tests.