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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

Quantitative Characterisation of Intertidal to Supratidal Sediments of the Abu Dhabi Coastline

Stephen Lokier1; Alice Knaf2; Thomas Steuber1

(1) Petroleum Geosciences, The Petroleum Institute, Abu Dhabi, United Arab Emirates.

(2) Department für Geo-und Umweltwissenschaften, LMU, Munich, Germany.

The Abu Dhabi coastline provides an ideal setting for the study of sedimentary systems inferred to be directly analogous to those which deposited many of the regions Mesozoic petroleum reservoirs. Improved understanding of these complex depositional environments, supported by quantitative sedimentological data, is essential to the development of accurate depositional models and reliable simulations for carbonate reservoirs.

The arid southern shore of the Arabian Gulf has an extremely low-angle ramp geometry. The coast is locally protected from open marine conditions by a number of peninsulas and offshore shoals and islands. Sedimentary processes in the supratidal zone are dominated by the precipitation of evaporite minerals in the shallow sub-surface. A broad carbonate-evaporite intertidal setting, characterised by complex depositional facies geometries, passes off-shore, into a subtidal carbonate depositional environment.

The coastline of the United Arab Emirates is currently undergoing massive infrastructure development at an unprecedented scale, with huge dredging and island-building projects changing the sedimentary dynamics of the coast beyond recognition. The impending loss of many of the natural coastal systems gives further impetus to the need for accurately recording these sedimentary environments before they are eradicated by the anthropogenic overprint.

This study employs a range of analytical techniques to investigate and characterise the surface sediments of the supratidal and intertidal zones of the Abu Dhabi coastline. Multiple transects were established between the lower intertidal and supratidal zones to the southwest of Abu Dhabi Island. Sampling stations were identified at regular intervals and the surface sediments were described and sampled. Samples were returned to the laboratory for detailed analysis.

The results of this study exhibit clear trends in the composition, grainsize and maturity of sediments within the current depositional architecture of the Abu Dhabi coastline. High-energy lower intertidal zone facies are dominated by coarse grained ooidal and bioclastic sediments that grades into very fine carbonate and gypsiferous sands in the supratidal zone. Analysis of facies distribution allows us to establish quantitatively-constrained facies geometries that can be applied as a recent analogue in the development of our understanding of sub-surface facies distribution and its control on reservoir development.