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.