The 1D and 2D Model of Petroleum System Analysis for the Ratawi Oil Field by PetroMod Software

Abstract

The Ratawi Oilfield is located in the southeastern part of Iraq within Basra Governorate, it is 70 km west of the Basra City center and towards west about 12 km from the North Rumaila Oilfield. The PetroMod software was used in the research and two models were created. 1D model through which the elements and processes of the petroleum system were determined, and 2D model through Rt-1, Rt-2, and R-172 oilwells, hybrid migration type was chosen between Darcy and Flowpath. The results showed the migration pathways for each of the Butmah, Sargelu, and Sulaiy formations to the main reservoirs of the Ratawi Oilfield, which are the Mishrif, Mauddud, Nahr Umr, Zubair, and Yamama formations. The results of laboratory tests and studies showed that the oils from the reservoirs of the Ratawi Oilfield were generated from more than one source rock. Therefore, this indicates the presence of a fault system that penetrates the Gotnia Formation, which is characterized by high thickness, and that these faults are of an open type that leads to the migration of the oil from the source rocks below the Gotnia Formation to the upper reservoir units in this field. This conclusion was made by creating 2 scenarios: The first scenario/possibility of the presence of hydrocarbons with absence of a fault. The results of the petroleum system analysis in the study area showed the hydrocarbon accumulation in the reservoir’s formations with a percentage of 15.7% associated gas and 84.3% of oil generated from the source rocks represented by the Sulaiy Formation. The second scenario/possibility of hydrocarbon accumulation-the presence of a fault shows the possibility of an open fault that cuts through a high-thickness of the Gotnia Formation. Therefore, the migrated oil through the fault to reservoir’s formations (Mishrif, Mauddud, Nahr Umr, Zubair, and Yamama) came from the source formations (Butmah, Sargelu, Sulaiy).