--> ABSTRACT: Chronostratigraphy of Two Carbonate Successions: Lower Cretaceous Shu’aiba Formation and Jurassic Platform Hanifa-Arab to Gotnia Basin Transition, Saudi Arabia, by Steinhauff, David M.; Gregory, Arthur; #90135 (2011)

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Chronostratigraphy of Two Carbonate Successions: Lower Cretaceous Shu’aiba Formation and Jurassic Platform Hanifa-Arab to Gotnia Basin Transition, Saudi Arabia

Steinhauff, David M.1; Gregory, Arthur 2
(1) EXPEC ARC, Saudi Aramco, Dhahran, Saudi Arabia. (2) Exploration Resource Assessment, Saudi Aramco, Dhahran, Saudi Arabia.

Recent advances in chronostratigraphic and visualization software allow rapid, detailed analysis of 3D seismic previously not possible. The interpreter defines geometries and stacking patterns and assigns packages characterized by particular geometries to one of four categories: (1)highstand systems tract (HST); (2) transgressive stage systems tract (TST); (3) falling stage systems tract (FSST); and (4) lowstand systems tract (LST). Here we interpret two complex carbonate systems over large 3D, on-shore, seismic volumes.

Analysis of the southern Rub’ Al-Khali, Lower Cretaceous Shu’aiba Formation shows that (1) relative position with respect to the shelf, basin margin, and basin determined where the sequences were deposited; (2) the number of interpreted sequence boundaries and sequences fall within the range reported by others; (3) the average duration of the systems tracts likely ranges from about 6.5 to 1.5 Ma; (4) the top Shu’aiba typically coincides with a FSST or LST; (5) the base Shu’aiba is a consistent seismic marker, typically coinciding with a HST or FSST; and (6) the top Shu’aiba is a less consistent seismic marker than the base. A top Shu’aiba surface terminating with a FSST or LST is consistent with subaerial exposure reported by most workers. The base Shu’aiba seismic marker is consistent with a HST or FSST and agrees with the findings of others who considered the base Shu’aiba to have deeper water affinities.

Along the northern Saudi Arabian Jurassic platform to basin transition, seismic flattening on the Dhruma Shale event combined with filtering significantly improved data quality, allowing detailed chronostratigraphic analysis. Analysis of the Hanifa-Arab platform and Gotnia basin shows that the Gotnia salt sequences (north of the Gotnia margin) may predate the Arab-D sequence in this area. This analysis further suggests that the salt was deposited during a post-Hanifa, basin-wide sea level fall.

These examples illustrate breakthroughs that would have been difficult, if not impossible, to achieve using other methods. In the first case, a much better understanding of the timing, number, and relative importance of various systems tracts was rapidly gained over a two-week period. In the second, new insights on the relative timing of platform and basin successions was achieved in an area where biostratigraphic control linking the platform and basin was limited.

 

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.