--> Abstract: Late Carboniferous-Permian (Unayzah/Gharif) New Play Fairway Potential in Saudi Arabia: Integration of Sequence Stratigraphy, Palaeogeography, Reservoir-Seal Distribution and Basin Modeling, by Roger J. Price, Andrew Jollands, Pierre J. Van Laer, and David R. Fell; #90039 (2005)

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Late Carboniferous-Permian (Unayzah/Gharif) New Play Fairway Potential in Saudi Arabia: Integration of Sequence Stratigraphy, Palaeogeography, Reservoir-Seal Distribution and Basin Modeling

Roger J. Price1, Andrew Jollands1, Pierre J. Van Laer1, and David R. Fell2
1 Saudi Aramco, Dhahran, Saudi Arabia
2 First Calgary Petroleums Ltd, Calgary, AB

A regional west to east well section across the Arabian Plate illustrates the contemporaneous sequence stratigraphy of the Unayzah-Juwayl/Gharif-AlKhlata formations of Saudi Arabia and Oman respectively. The sequence stratigraphy combined with selected palaeogeographic maps (from a series of 11) depict the changing depositional settings of the area over a period of approximately 60 million years (305-245 MYBP) when the Arabian Plate moved northwards from around 45 degrees to 15 degrees south. Numerous intervals of proven and new reservoir potential are discussed as postulated from these maps.

The depositional environments of the Unayzah B-C/AlKhlata are predominantly glacio-fluvial and lacustrine sediments. The overlying Unayzah A contains aeolian dune, fluvial and playa complexes whilst the contemporaneous Lower & Middle Gharif sequences have transgressive marine sands to shallow marine carbonates, overlain by regressive shoreline sands succeeded by fluvial and playa systems. The overlying Basal Khuff Clastics/Upper Gharif is a fluvial dominated sequence.

One example covering the Unayzah A/Middle Gharif sequence is used to illustrate the distribution of gross, clean and porous sands. These maps have been integrated with maturation and migration studies of the Qusaiba (Silurian) shale source rock. Additionally, top seal quality related to thickness of the overlying Basal Khuff Carbonate is combined with the different contemporaneous depositional facies within the Unayzah/Gharif, which offer new possible reservoir opportunities. The resulting integrated map outlines potential new play fairways with associated risks based upon the distribution of the above hydrocarbon system components.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005