Abstract: Great Unity Oilfield, one of the main productive ares of Sudan 1/2/4 project, lies on the central uplift belt in Muglad Basin. Structure of Great Unity is a large-scale faulted anticline, with 3 trap patterns developing on it, i.e., anticline, fault-nose and fault-block. The Great Unity structure has large amount of traps with 29 structural traps on top Aradeiba A. Abu Gabra formation source rock and multiple sets of reservoirs including Bentiu, Aradeiba, Zarqa, Ghazal and Baraka, etc, form the multi-oil-water system called "stacked plate pattern" reservoirs which have many oil-bearing formations and long oil-bearing well sections. Most are layered reservoirs. Analysis of key factors of reservoir accumulation indicated that the major faults are the vertical migration pathways of hydrocarbons. Oil and gas accumulated along the major faults. The lateral sealing condition was crucial to form an effective fault-block trap.

Key words: Great Unity Oilfield, trap, reservoir accumulation conditions, reservoir feature, key factor