Print this pageAAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Modeling Hydrocarbon Generation in North Melut Basin
(1) Exploration, Petrodar Operating Co., Khartoum, Sudan.
(2) Earth and Life Science Tectonic Group, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
The Melut Basin is in essence a continental rift basin in the generally accepted knowledge, it experienced three phases of extension from Neocomian to Oligocene times each associated with thermal subsidence stages and possibly with important episodes of non-deposition and/or erosion. The basin constitutes part of the larger Central Africa Rift system and, considers as one of major hydrocarbon provinces in Sudan, which witnessing substantial exploration activities.
During the second rift cycle (Campanian- Maastrichtin) normal faults were reactivated again allowing for the deposition of organic-rich shale and claystone deposited mainly in lacustrine, marginal lacustrine and deltaic environments. The organic rich shale and claystone of Galhak and Alrenk Formations form the principle source rock in the Melut Basin. The source rock kerogen is predominantly derived from lacustrine algae with subordinate terrestrial woody plants debris.
An attempt has been made in this work to model the hydrocarbon generation of source rocks in north Melut Basin using Petromod 1D and 2D packages. The principle objective is to investigate the temporal and spatial variation of thermal maturity of the Cretaceous source rocks in Melut basin. Two seismic sections and 6 wells were selected for this purpose. 1D models were constructed for all six wells. Data-base was generated including information about the stratigraphy, lithology, tectonic event and geochemical data. Boundary conditions (paleo-heat flow, Paleo-bathymetry and paleo sediment water interface temperature) are deduced. The resulted model was calibrated with the VRo and BHT data to produce a best fit between the observed and model curves.
Using the obtained knowledge of 1D hydrocarbon generation model, two geological cross sections were built from seismic sections, then calibrated and simulated. The resulted models show a considerable correlation in timing of oil generation and expulsion. The Tertiary strata are immature to marginally mature basin wide. While the cretaceous source rocks are active at the present day only in basement high areas while in the deep basinal areas these rocks are over mature. Peak oil generation of Alrenk and Galhak formations was attained around 54 Ma and 45 respectively. The present day transformation ratio (TR) of Alrenk source is between 80-90% implying that this unit converted most of its potentiality to hydrocarbons with very little remain to be expelled.