Unveiling Mediterranean Heterogenous Gas Reservoirs Through Pressure Points Analysis and Reservoir Simulation Modelling

Abstract The West Nile Delta basin is a significant petroleum region in the Mediterranean, hosting numerous gas and condensate fields. These fields consist of a combination of structural and stratigraphic traps with sandstone reservoirs from the Miocene and Pliocene epochs, where turbidite hydrocarbon reservoirs with substantial hydrocarbon volumes are found. This article focuses on the Miocene gas reservoir of the Abu Madi formation in the Abu Qir and Yazzi offshore gas fields, located in the West Nile Delta basin north of Alexandria, Egypt. The study integrates recorded formation pressure testing points and production history of 6 wells that intervened Abu Madi Formation to identify isolated compartments that do not contribute to field production. The analysis revealed three gas reservoirs. The first reservoir, in the North Abu Qir field, has experienced long-term production, leading to pressure depletion and aquifer sweep, reducing the depth of the gas-water contact. The second reservoir, in the Yazzi field, shows some pressure depletion affected by the first reservoir production, but its gas-water contact remains at its initial depth. The third reservoir, in the eastern compartment, exhibits partial pressure depletion. The conceptual model proposes two main concepts for the relationship between the three gas reservoirs. The first concept involves the local structural framework, where the Abu Madi formation trap consists of multiple anticlines, with spill points playing a crucial role in filling hydrocarbons in these anticlines with the same water contact. The second concept considers the impact of stratigraphic facies changes and heterogeneity on transmissibility and permeability, affecting volumetric recovery efficiency. The information was compiled into a 3D reservoir simulation model, concluding that the remaining hydrocarbons must be redistributed. This opens the possibility of hydrocarbon accumulation in partially isolated compartments that need development. Additionally, the interpretation of recorded formation pressure testing points gradients was essential in identifying hydrocarbon fluid types, revealing an oil rim in the gas reservoir in the eastern compartment of the Abu Qir gas field, which altered the well development strategy in that area.