HYDROCARBON GENERATION AND MIGRATION FROM BARREMIAN – APTIAN SOURCE ROCKS, NORTHERN ORANGE BASIN, OFFSHORE WESTERN SOUTH AFRICA: A 3D NUMERICAL MODELLING STUDY

Reconstructed thermal and structural histories derived from new AFTA Apatite Fission Track Analysis, vitrinite reflectance and (U-Th)/He apatite dating results from the Morum–1 well, Otway Basin, reveal that the Morum High is a mid-Tertiary inversion structure. Uplift and erosion commencing in the Late Paleocene to mid-Eocene (57–40 Ma) removed around 1,500 m of sedimentary section. The eroded section is attributed to the Paleocene- Eocene Wangerrip Group which is considered to have been deposited in a major depocentre in the vicinity of the present Morum High. This depocentre is interpreted to have been one of a number of transtensional basins developed at the margin of the Morum Sub-basin and adjacent to the Tartwaup Hinge Zone and Mussel Fault during the Early Tertiary. The Portland Trough in Victoria represents a similar depocentre in which over 1,500 m of Wangerrip Group section, mostly represented by deltaic sediments of the Early Eocene Dilwyn Formation, is still preserved.Quantification of the maximum paleotemperature profile in Morum–1 immediately prior to Late Paleocene to mid-Eocene inversion shows that the paleo-geothemal gradient at the time was between 21 and 31°C/km, similar to the present-day level of 29°C/km, demonstrating that there has been little change in basal heat flow since the Early Tertiary.Reconstruction of the thermal history at the Trumpet–1 location reveals no evidence for any periods of significant uplift and erosion, demonstrating the relative stability of this part of the Crayfish Platform since the Late Cretaceous.The thermal and burial histories at Morum–1 and Trumpet–1 have been used to calibrate a Temis2D hydrocarbon generation and migration model along seismic line 85-13, encompassing the Crayfish Platform, Morum High and Morum Sub-basin. The model shows the cessation of active hydrocarbon generation from Eumeralla Formation source rocks around the Morum High due to cooling at 45 Ma (within the range 57–40 Ma) resulting from uplift and erosion of a Wangerrip Group basin. There has been almost no hydrocarbon generation from the Eumeralla Formation beneath the Crayfish Platform.Migration of hydrocarbons generated from the Eumeralla Formation began in the Late Cretaceous in the Morum Sub-basin and is predicted to continue to the present day, with the potential for accumulations in suitably placed reservoirs within the Late Cretaceous package both within the Morum Sub-basin and at the southern margin of the Crayfish Platform.

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Geochemical Evaluation of the Cretaceous Mudrocks and Sandstones (Wackes) in the Southern Bredasdorp Basin, Offshore South Africa: Implications for Hydrocarbon Potential

Minerals ◽

10.3390/min10070595 ◽

2020 ◽

Vol 10 (7) ◽

pp. 595

Author(s):

Temitope Love Baiyegunhi ◽

Kuiwu Liu ◽

Oswald Gwavava ◽

Nicola Wagner ◽

Christopher Baiyegunhi

Keyword(s):

South Africa ◽

Oil And Gas ◽

Vitrinite Reflectance ◽

Source Rocks ◽

Geochemical Data ◽

Minor Amount ◽

Hydrocarbon Potential ◽

Hydrocarbon Generation ◽

Thermal Maturity ◽

The Mean

The southern Bredasdorp Basin, off the south coast of South Africa, is only partly understood in terms of its hydrocarbon potential when compared to the central and northern parts of the basin. Hydrocarbon potential assessments in this part of the basin have been limited, perhaps because the few drilled exploration wells were unproductive for hydrocarbons, yielding trivial oil and gas. The partial integration of data in the southern Bredasdorp Basin provides another reason for the unsuccessful oil and gas exploration. In this study, selected Cretaceous mudrocks and sandstones (wacke) from exploration wells E-AH1, E-AJ1, E-BA1, E-BB1 and E-D3 drilled in the southern part of the Bredasdorp Basin were examined to assess their total organic carbon (TOC), thermal maturity, organic matter type and hydrocarbon generation potential. The organic geochemical results show that these rocks have TOC contents ranging from 0.14 to 7.03 wt.%. The hydrogen index (HI), oxygen index (OI), and hydrocarbon index (S2/S3) values vary between 24–263 mg HC/g TOC, 4–78 mg CO2/g TOC, and 0.01–18 mgHC/mgCO2 TOC, respectively, indicating predominantly Type III and IV kerogen with a minor amount of mixed Type II/III kerogen. The mean vitrinite reflectance values vary from 0.60–1.20%, indicating that the samples are in the oil-generation window. The Tmax and PI values are consistent with the mean vitrinite reflectance values, indicating that the Bredasdorp source rocks have entered the oil window and are considered as effective source rocks in the Bredasdorp Basin. The hydrocarbon genetic potential (SP), normalized oil content (NOC) and production index (PI) values all indicate poor to fair hydrocarbon generative potential. Based on the geochemical data, it can be inferred that most of the mudrocks and sandstones (wackes) in the southern part of the Bredasdorp Basin have attained sufficient burial depth and thermal maturity for oil and gas generation potential.

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A 3D Numerical Modelling Study on Temperature and Salinity Structure along Coastal Waters of Kochi during Northeast Monsoon

Journal of Coastal Research ◽

10.2112/si89-006.1 ◽

2020 ◽

Vol 89 (sp1) ◽

pp. 32

Author(s):

Reghu Gayathri ◽

Vinjamuri Ranga Rao ◽

Valavala Damodara Rao ◽

Durairaj Kumaresan

Keyword(s):

Numerical Modelling ◽

Coastal Waters ◽

Northeast Monsoon ◽

3D Numerical Modelling ◽

Salinity Structure ◽

Modelling Study

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Thermal history, hydrocarbon generation and migration in the Horn Graben in the Danish North Sea: a 2D basin modelling study

International Journal of Earth Sciences ◽

10.1007/s00531-007-0247-2 ◽

2007 ◽

Vol 97 (5) ◽

pp. 1087-1100 ◽

Cited By ~ 14

Author(s):

Andreas Beha ◽

Rene O. Thomsen ◽

Ralf Littke

Keyword(s):

North Sea ◽

Thermal History ◽

Hydrocarbon Generation ◽

Basin Modelling ◽

And Migration ◽

Modelling Study

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An Integrative Modeling Approach to Estimating Volume of Generated Oil from Lower Cretaceous Sulaiy Formation in Southern Iraq

Iraqi Geological Journal ◽

10.46717/igj.54.1c.9ms-2021-03-29 ◽

2021 ◽

Vol 54 (1C) ◽

pp. 114-136

Author(s):

Basim Alkubaisi

Keyword(s):

Lower Cretaceous ◽

Quantitative Estimation ◽

Organic Content ◽

Source Rocks ◽

Hydrocarbon Generation ◽

Thermal Maturation ◽

High Maturity ◽

Sulaiy Formation ◽

And Migration ◽

Southern Iraq

Thermal maturity and petroleum generation capacity of the source rocks of Lower Cretaceous Sulaiy Formation were studied and evaluated via modeling the thermal maturation of ten wells in this study by using the Arrhenius equation for chemical reactions or (time-temperature index of thermal maturation). A thermal maturation map of the Sulaiy Formation shows that it a high maturity level increasing eastward; also, the geochemical analysis indicated suitable organic content in quantity and quality to generate hydrocarbons. The onset of oil migration from the Sulaiy Formation is calculated by this study to be at the end of Lower Eocene time (53 million years ago), and as it is a late hydrocarbon generation and migration; thus indicating mainly vertical migration paths. According to quantitative estimation, the oil generated and migrated vertically from the Sulaiy Formation towards the Lower Cretaceous reservoirs in southern Iraq estimated at 42.6 x 109 bbl. This study elevated the status of the Sulaiy Formation to a major source of oil tapped in the Lower Cetaceous reservoirs of southern Iraq.

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