Print this pageSaudi Arabian Silurian and Devonian Sequence Stratigraphy, Paleogeography and Play Concepts
By
Michael L. Hulver1, Riyadh A. Rahmani1, Patrick M. Rutty2, Ronald J. Steel3, Robert S. Johnson2, Randall G. Demaree2
(1) Saudi Aramco, Dhahran, Saudi Arabia (2) Saudi Aramco, (3) University of Wyoming, Laramie, WY
A third-order sequence stratigraphic model of the Silurian and Devonian
systems
in Saudi Arabia has been constructed, using detailed sedimentologic,
lithostratigraphic and biostratigraphic data from 50 wells and approximately
10000 feet of core from the Kingdom’s Paleozoic basins. Eight third-order
sequences were identified and correlated from the base of the Silurian Qusaiba
Member to the Devonian Jubah Formation. Six depositional systems tracts were
recognized in the section: offshore marine highstand, offshore marine lowstand,
offshore marine transgressive, tide-dominated transgressive, fluvial-deltaic
forced regressive, and wave-dominated forced regressive.
Mapping of the systems tracts
highlighted several key features: 1) the
ongoing influence of Infra-Cambrian basins on Silurian and Devonian
paleogeography; 2) a clear second-order basinward progradation of the shoreline
during the Devonian; 3) a persistent clastic depocenter on the eastern side of
Ghawar; 4) development in the northwest of a broad shelf with local carbonate
sedimentation; and 5) periodic Devonian exposure of the Qatar arch, which -
along with the stable east edge of Ghawar and the Niban arch to the south -
formed a recurrent embayment in which were deposited restricted marine facies,
including the reservoir units of the Jauf Formation.
In light of this new sequence stratigraphic interpretation, analysis of trap elements has enabled better risk assessment of various existing play types, and has helped identify new play concepts.