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An Integrated Approach to Constraining Key Sequence Boundaries: The Wasia Formation, Northern Saudi Arabia

W. Tan1, D.Z. Tang1, and A. Mohsin1

1Saudi Aramco


The Cretaceous Wasia Formation is of Albian-Turonian age. It contains a total of seven significant carbonate and siliciclastic hydrocarbon-bearing intervals located onshore and offshore Northeastern Saudi Arabia. The Wasia Formation, bounded by two regional unconformities, forms a second-order sequence (approximately 20 M.Y. duration) representing a transition from siliciclastic-dominated systems (Khafji and Safaniya) to carbonate-dominated depositional systems (Mauddud, Ahmadi, Rumaila and Mishrif).

A combination of seismic stratigraphy, well-log correlations, core/drill-cuttings sedimentology, biostratigraphy and chemostratigraphy is used to assist unraveling the sequence stratigraphic framework of the Wasia second-order sequence. This integrated approach is found to be a powerful tool to carefully identify and constrain third-order sequence boundaries within the Wasia Formation. A number of third-order sequence boundaries have been recognized in ascending order: a basal Wasia unconformity, and the top boundaries of the Khafji, Safaniya, Mauddud, Ahmadi, Rumaila, and Mishrif sequences. These sequence boundaries have been utilized to map geometries of the Wasia 2nd order and its internal 3rd order sequences. Additionally, this newly built regional sequence stratigraphic framework facilitates an in-depth understanding of the evolution of the Wasia depositional systems and their exploration potential.


AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain