Modeling Study and Comprehensive Evaluation of Petroleum System in Abyei Slope of Kaikang Depression, Muglad Basin

Abstract

AbstractThe Muglad Basin is the largest sedimentary basin in the Central African Rift, covering an area of more than 120,000 km2. It is also the basin with the largest discovered geological reserves in the Central African Rift, and it has a total of more than 8 billion barrels of discovered geological reserves. In order to evaluate the petroleum resource potential and optimize the exploration target of the Abyei slope, a modeling study of petroleum systems was carried out. Through the simulation of burial history, thermal history, hydrocarbon generation history and migration and accumulation history, the history of source rock thermal evolution and hydrocarbon generation was clarified. Moreover, the favorable direction of hydrocarbon migration and accumulation was also determined. Based on the research of petroleum simulation, the division and evaluation of petroleum systems were completed. According to the research, the source rock of Abu Gabra formation has the strongest hydrocarbon generation ability, the Baraka formation’s is the second, and the Ghazal formation’s is the worst. The Abu Gabra organic matter starts to generate hydrocarbons from 113 Ma, and it has entered a high-mature and over-mature stage. The peak oil generation period is from 80 Ma to 60 Ma, and the gas production is dominated after 60 Ma. The organic matter of Ghazal and Baraka formation start to generate hydrocarbons from 65 Ma to 60 Ma, and the peak of oil generation is from 20 Ma to the present. Vertically, Bentiu formation, the middle Aradeiba, and lower Ghazal, Baraka, and Nayil are the effective hydrocarbon accumulation layers. Horizontally, the central and west are the favorable areas for oil and gas accumulation. There are three sets of petroleum systems in the study area and they are Abu Gabra-Bentiu, Aradeiba, Zarqa(!), Ghazal- Gazal(*), Baraka-Baraka, Amal, Nayil(*). The source-reservoir-cap rock combinations, pathway system and conservation conditions of two sets of petroleum systems in Cretaceous formation are comprehensively superior to that of the Tertiary, and they present a better exploration and production potentials. Based on the simulation and comprehensive evaluation of the petroleum system, the favorable zones and trap targets were selected and the exploration well locations were proposed. The research results point out the direction for Cretaceous oil and gas exploration in the Abyei slope.KeywordsBasin modelingSource rockPetroleum systemMuglad Basin