Abstract: After 30 years of exploration in Raoyang sag, the buried hill reservoir featuring in large scale, shallow depth, and simple structure has been discovered. Buried hill study and analysis of reservoir accumulation conditions in the past few years indicate that Raoyang sag has huge exploration potential and a lot of small and deep buried hill traps, internal traps of buried hills and other types of buried hill traps need to be further studied and evaluated. Changyangdian buried hill structural belt and Suning buried hill structural belt have low exploration degree and complicated reservoir accumulation conditions, so the exploration work has been stagnant at one time. In 2006, Huabei Oilfield Company laid emphasis on the exploration of deep buried hills, listing Changyangdian and Suning buried hill structural belts as key exploration zone, fully using newly acquired 3D seismic data to find buried hill traps. Beginning with the old data, through finding out new hints to develop new recognitions, re-examining old wells to solve difficulties, identifying buried hill horizons through strata contrast and tracking, focusing on the key of reservoir accumulation, reinforcing evaluation on oil sources, creating new geological cognitions, building buried hill reservoir accumulation models, the company discovered buried hill traps in Chang 3, Chang 6 and Ninggu 8x wells. After drilling, high-production commercial oil and gas flow is gained, and new breakthroughs in buried hill exploration are fulfilled.

Key words: Raoyang sag, deep buried hill, internal buried hill, new-generation-old reservoir-old sealing formation