A Reassessment of the Holocene Abu Dhabi Sabkha as a Predictive Analogue for the Reservoir Facies of the Arab Formation

Lokier, Stephen. W.¹ (1) The Petroleum Institute, Abu Dhabi, Abu Dhabi, United Arab Emirates

The Holocene to Recent evaporite and carbonate sediments of the Abu Dhabi sabkha have been extensively applied as an analogue for the formation of mixed carbonate-evaporite units throughout the world such as the regionally important Jurassic Arab Formation. However, it has been increasingly recognised that this interpretation may not be truly representative of the Arab Formation, and thus, may result in the construction of reservoir models that do not accurately predict subsurface geometries.

During this study the Abu Dhabi Sabkha is reexamined using integrated sedimentological, geochemical and palaeontological techniques. The results of this analysis are then applied to build a chronostratigraphically constrained sabkha model that can be applied to a more accurate interpretation of the Arab Formation. Specific focus is given to the following. The Abu Dhabi sabkha is widely regarded as comprising laterally extensive homogenous facies belts trending parallel to the coastline. This study reveals complex facies heterogeneity at all scales. Sequence stratigraphic models of the Arab Formation have typically employed lithostratigraphic rather than chronostratigraphic correlations. This has resulted from a lack of stratigraphic control due to a paucity of stratigraphically significant fossils and poor isotopic control resulting from the chemically complex sabkha environments. Early and post depositional diagenesis are important controls on reservoir quality in sabkha-deposited sequences. Many studies and reservoir models fail to consider the roll of primary depositional facies on subsequent diagenetic processes. Such an understanding is vital if predictive reservoir models are to be developed.