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Title: Subsalt source rock maturity in the Sudanese Red Sea

Abstract

Thermal modeling can demonstrate that stratal salt deposits may provide a significant heat conduit and conceptually provide a basis for hypothermal fairways of hydrocarbon aspiration in regions of dominant thermal overmaturity. However, accurate evaluation of thermal maturity suppression by modeling must be geologically constrained. With respect to the Tertiary Tokar Delta of offshore Sudan, ID tectonic subsidence analysis of boreholes in the region reveals at least two major pu1ses of crustal extension and associated heating (24-20 m.a. and 5.4-2.7 m.a.). Integrating the borehole geochemical information with a Tokar Delta seismic stratigraphic interpretation allows the construction of constrained 2D thermal basin models through time using Procom BMT. The best match between the observed and modelled vitrinite reflectance values is achieved by using a two phase tectonic stretching model with pulses at 22{+-}2 m.a. and 4{+-}1.5 m.a. and incremental subcrustal stretching factors which vary between 2.65-2.75. Utilizing these parameters suggests the top of the oil window to occur within the Zeit Formation and bottom of the oil window to exist at the base of the Dungunab Salt. As only subsalt source rocks are observed, this model would tend to negate the possibility of the occurrence of liquid hydrocarbons. For the Tokar Deltamore » the presently observed general high heat flow is so high that it leads in all cases to overcooked organics for a subsalt source. However, that hydrocarbons in the post-salt Zeit Formation of the Tokar Delta have been discovered suggests significant secondary hydrocarbon migration to have occurred within the late Miocene (15.4 - 5.4 m.a.). Potential migration pathways would be a1ong basement-induced fault conduits. If true, similar secondary migration play concepts may be applicable elsewhere in the Red Sea.« less

Authors:
 [1]; ;  [2]
  1. Univ. of Oklahoma, Norman, OK (United States)
  2. Univ. of Oklahoma, Norman, OK (United States); and others
Publication Date:
OSTI Identifier:
127417
Report Number(s):
CONF-950995-
Journal ID: AABUD2; ISSN 0149-1423; TRN: 95:005942-0111
Resource Type:
Journal Article
Journal Name:
AAPG Bulletin
Additional Journal Information:
Journal Volume: 79; Journal Issue: 8; Conference: International conference and exhibition of the American Association of Petroleum Geologists, Inc.: managing change at the turn of the century, Nice (France), 10-13 Sep 1995; Other Information: PBD: Aug 1995
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; 58 GEOSCIENCES; HYDROCARBONS; MATURATION; THERMAL DEGRADATION; RED SEA; PETROLEUM DEPOSITS; EXPLORATION; SUDAN; OFFSHORE OPERATIONS; GEOTHERMAL GRADIENTS

Citation Formats

Geiger, C, Preussag Energie, Lingen, Pigott, J, and Forgotson, Jr, J M. Subsalt source rock maturity in the Sudanese Red Sea. United States: N. p., 1995. Web.
Geiger, C, Preussag Energie, Lingen, Pigott, J, & Forgotson, Jr, J M. Subsalt source rock maturity in the Sudanese Red Sea. United States.
Geiger, C, Preussag Energie, Lingen, Pigott, J, and Forgotson, Jr, J M. 1995. "Subsalt source rock maturity in the Sudanese Red Sea". United States.
@article{osti_127417,
title = {Subsalt source rock maturity in the Sudanese Red Sea},
author = {Geiger, C and Preussag Energie, Lingen and Pigott, J and Forgotson, Jr, J M},
abstractNote = {Thermal modeling can demonstrate that stratal salt deposits may provide a significant heat conduit and conceptually provide a basis for hypothermal fairways of hydrocarbon aspiration in regions of dominant thermal overmaturity. However, accurate evaluation of thermal maturity suppression by modeling must be geologically constrained. With respect to the Tertiary Tokar Delta of offshore Sudan, ID tectonic subsidence analysis of boreholes in the region reveals at least two major pu1ses of crustal extension and associated heating (24-20 m.a. and 5.4-2.7 m.a.). Integrating the borehole geochemical information with a Tokar Delta seismic stratigraphic interpretation allows the construction of constrained 2D thermal basin models through time using Procom BMT. The best match between the observed and modelled vitrinite reflectance values is achieved by using a two phase tectonic stretching model with pulses at 22{+-}2 m.a. and 4{+-}1.5 m.a. and incremental subcrustal stretching factors which vary between 2.65-2.75. Utilizing these parameters suggests the top of the oil window to occur within the Zeit Formation and bottom of the oil window to exist at the base of the Dungunab Salt. As only subsalt source rocks are observed, this model would tend to negate the possibility of the occurrence of liquid hydrocarbons. For the Tokar Delta the presently observed general high heat flow is so high that it leads in all cases to overcooked organics for a subsalt source. However, that hydrocarbons in the post-salt Zeit Formation of the Tokar Delta have been discovered suggests significant secondary hydrocarbon migration to have occurred within the late Miocene (15.4 - 5.4 m.a.). Potential migration pathways would be a1ong basement-induced fault conduits. If true, similar secondary migration play concepts may be applicable elsewhere in the Red Sea.},
doi = {},
url = {https://www.osti.gov/biblio/127417}, journal = {AAPG Bulletin},
number = 8,
volume = 79,
place = {United States},
year = {Tue Aug 01 00:00:00 EDT 1995},
month = {Tue Aug 01 00:00:00 EDT 1995}
}