AAPG Bulletin, V. 83, No. 12 (December 1999), P. 1943-1964.

Modeling Petroleum Generation in the Southern Muglad Rift Basin, Sudan¹

Abdalla Y. Mohamed,² Michael J. Pearson,³ William A. Ashcroft,⁴ James E. Iliffe,⁵ and Arthur J. Whiteman⁴

©Copyright 1999. The American Association of Petroleum Geologists. All rights reserved.

¹Manuscript received April 13, 1998; revised manuscript received April 5, 1999; final acceptance May 30, 1999.
²Department of Geology and Petroleum Geology, University of Aberdeen, King's College, Meston Building, Aberdeen AB24 3UE, Scotland, United Kingdom. Address in Sudan: Oil Exploration and Production Authority, Ministry of Energy and Mining, Khartoum, Sudan.
³Corresponding author. Department of Geology and Petroleum Geology, University of Aberdeen, King's College, Meston Building, Aberdeen AB24 3UE, Scotland, United Kingdom; e-mail: [email protected]
⁴Department of Geology and Petroleum Geology, University of Aberdeen, King's College, Meston Building, Aberdeen AB24 3UE, Scotland, United Kingdom.
⁵PGS Tigress, PSTI Technology, Exploration Drive, Aberdeen AB23 8GX, Scotland, United Kingdom. Present address: Integrated Interpretation Center, Exploration and Production Technology, Conoco Inc., Houston PR3036, P.O. Box 2197, Houston, Texas 777252-2197.

We are grateful to Chevron Overseas Petroleum Inc. and Robertson Research International for supplying through the Geological Research Authority of Sudan (Ministry of Energy and Mining) essential information that enabled this work to be carried out. PGS Tigress is acknowledged for making available the HEDERA™ software used in modeling.

ABSTRACT

Maturity and petroleum generation have been modeled in a 120-km-long northeast-southwest cross section of the Southern Muglad basin, Sudan. The section passes close to the Unity and Kaikang areas, which provide well control on the structure interpreted from gravity and seismic reflection profiles. Modeling of geotherms from corrected bottom-hole temperatures indicates present heat flows around 60 mW/m² in the well control areas. Using measured vitrinite data as calibrant, maturity can be modeled equally well with a constant paleoheat flow similar to the present day or with a complex heat flow pattern related to rifting. A geologically realistic complex heat flow model was employed to calculate the timing of generation and expulsion from the Lower Cretaceous lacustrine source rocks of the Abu Gabra and Sharaf formations. Kinetic (Easy% R_o) calculation of vitrinite maturity indicates a projected oil preservation depth limit around 4000 m shallowing to around 3500 m northeast of Unity near the basin margin.