Abstract:

Fula oilield in Muglad basin, Sudan, is mainly consisted of shallow ordinary heavy oil reservoirs in Cretaceous Aradeiba and Bentiu Formations and light oil and gas reservoirs in Cretaceous Abu Gabra Formation. The reservoir in Bentiu Formation in the major Fula North Block is a faulted anticlinal massive reservoir in a horst block with a dipping oil water contact. In the Aradeiba Formation there are shallow lake facies thin sandstone reservoirs with high porosity and permeability. While braided river facies thick bedded massive sandstone reservoirs with high porosity and permeability are developed in the Bentiu Formation. The Aradeiba and Bentiu reservoirs are characterized by shallow burial depth, loose consolidation, good poroperm characteristics, high sand production and low formation pressure, and the crude oils are characterized by high density, high viscosity, high acid value and heavy oil. The layered reservoirs in Abu Gabra Formation are of delta front facies thin sandstone reservoirs with medium porosity and medium permeability, being characterized by small fault block, rapid facies change and low hydrocarbon column. The oil and gas accumulations in Abu Gabra Formation are mainly controlled by lateral sealing conditions and poroperm characteristics of the reservoirs. Effective source-reservoir-cap rock combination, and lateral blocking of mudstones are the main control factors of oil and gas accumulations in Darfur Group and Bentiu Formation.

Key words: Muglad basin, Fula oilfield, geological feature, heavy oil