Genetic analysis of interior reservoirs in metamorphic buried hill of Liaohe Depression

Many interior fractured reservoirs have been discovered in buried hills of metamorphic rock in exploration of Liaohe Depression in recent years. It is cognized that oil and gas could accumulate in deep buried hills of metamorphic rock. This paper summarizes the characteristics of interior buried hill reservoirs of metamorphic rock and analyzes the control effect of lithology, source rock and oil window on the formation of interior buried hill reservoirs. The study shows that there are many lithologic associations showing laminar-like distribution vertically; fracture development was subject to both tectonic movement and advantageous lithology; the advantageous lithology sequence decided the alternative development of reservoirs and barriers; the proper configuration of reservoirs, barriers and source rocks provides possibility of hydrocarbon accumulation in interior buried hills; and hydrocarbon distribution is controlled by interior fracture system and tight barriers. The knowledge of interior reservoirs in buried hills of metamorphic rock has broadened exploration area.