Multidimensional Basin Modeling in the Central Persian Gulf basin (offshore Iran) and the Dniepr-Donets basin (Ukraine)
Research output: Thesis › Doctoral Thesis
3D and 2D basin models have been established for the Central Persian Gulf basin (offshore Iran) and the Dniepr-Donets basin (DDB; Ukraine) in order to study basin evolution and its link to hydrocarbon generation, migration and accumulation. The Central Persian Gulf basin is one of the richest regions of the world in terms of hydrocarbon resources and hosts super-giant gas accumulations in Permo-Triassic reservoirs including the South-Pars Field. In addition, oil is found in Cretaceous reservoirs. Although Silurian organic matter-rich sediments might be missing in the South-Pars area, a Silurian source rock (Sarchahan Fm.) is generally accepted for the gas/condensate, whereas Jurassic source rocks and lateral migration have been suggested for the oil accumulation. The 3D basin models show that present-day heat flow is about 65 mW/m², whereas heat flow during Cenozoic maximum burial was in the range of 60 to 68 mW/m². Oil and gas generation from Silurian horizons commenced during Jurassic and Late Cretaceous time, respectively. Gas generation continued till Neogene time. Models with 50 m thick Silurian “hot shales” (TOC 8 %; HI 470 mg HC / g TOC) successfully predict the gas accumulations in the study area (e.g. South Pars, Golshan, Balal fields) and their gas volume. By contrast, scenarios with thinner “hot shales” and models without the Sarchahan Formation along the Qatar-South Fars Arch are not capable of predicting the known accumulations. This suggests that prolific Silurian source rocks are present in the study area, although lateral gas migration from the south (e.g. from the Qatari portion of the South Pars/North Dome field) cannot be excluded. The 3D basin model also shows that Jurassic (and Cretaceous) source rocks in the study area are not mature enough to generate significant amounts of oil and, thus, supports long distance lateral migration of oil present in Mesozoic reservoirs. The DDB is a Late Devonian intracratonic rift basin with a complex geological history involving salt tectonics and Permian and Cretaceous erosion events. The DDB hosts major gas and a minor oil deposits. Previous 1-D studies suggested relatively high Permian heat flows, which resulted in a Late Carboniferous to Early Permian hydrocarbon generation phase. In the present study the effect of the Permian heating event and of salt diapirism on hydrocarbon generation is studied using a 2D basin modeling approach. Four cross-sections trending perpendicular to the basin axis have been modeled and calibrated with temperature and maturity data from 18 wells. The results show that present-day heat flows are in the range of 40 to 60 mW/m², whereas Mesozoic and Cenozoic heat flow was only 30 to 57 mW/m². A higher heat flow is postulated for Permian time (47-95 mW/m²). As expected the isotherms are strongly influenced by salt structures. Because of deeper Paleozoic burial, Carboniferous source rocks are more mature in the southeastern part of the DDB and hydrocarbon generation occurred earlier than in its northwestern part.
|Translated title of the contribution||3D und 2D Beckenmodelle im zentralen Persischen Golf (offshore Iran) und im Dniepr-Donets Becken (Ukraine)|
|Publication status||Published - 2013|