Coupling stratigraphic and petroleum system modeling tools in complex tectonic domains: case study in the North Algerian Offshore

International audienceIn the eastern Algerian offshore basin, 3D basinmodeling applied for facies prediction and petroleumpotentialassessment shows that most favorable zones for reservoir developmentand hydrocarbon occurrence are located at a maximumdistance of 60 km from the coastline. The lack of welldata in this area is partly compensated by a large data set ofgeophysical and geological (G&G) data such as multichannelseismic (MCS), magnetism, wide angle velocity models, andgeological outcrops; they represent important constraints for3D dynamic modeling. Facies distribution model isconstrained by sequence and environment evolution throughtime that is defined from onshore outcrops. 2D structural reconstitutionand thermal modeling were also undertaken withArcTem software. The structural interpretations highlight theoccurrence of north-verging ramps during the Quaternarywhich played an important role in HC generation and migration.Three source rocks have been considered for maturationmodeling with Temis Flow software, Burdigalian, Langhian,and Tortonian. They are found to be in gas window in the deepareas and locally in oil window at shallower structured zones.The modeling results indicate that the main fluid dischargewas focused toward the southern border of the offshore basinwhere recent thrust faults (parallel to the margin) are located.In order to test the role of these faults in terms of hydrocarbonmigration and trapping, two scenarios are considered accordingto whether they were sealed or not. In both cases, the 2D/3D simulations depict overpressures (2,000–4,000 psi) in thepre-salt sedimentary package. However, the hydrocarboncharge is most efficient with the sealing faults for the lowerLanghian and lower Messinian reservoirs. The hydrocarbonpotential depends mostly on the lateral extension of seals, theirsealing capacity and the organic carbon (TOC) content ofpotential source rocks. Besides, the sea drop of about 1,000 m during theMessinian salinity crisis has induced depressurizationthat caused oil and gas seepage from Miocenereservoirs