Seismic Stratigraphy and Depositional Environments of the Late Aptian Upper Shuaiba/Upper Bab Member Play of South East Abu Dhabi
ALMansoori, Abdulla 1; Ben Maroof, Muneera 1; Vahrenkamp, Volker C.*1
(1) Expolration, ADCO, Abu Dhabi, United Arab Emirates.
The Cretaceous Shuaiba Formation was deposited in the Aptian on the southern part of the Arabian Plate, consisting of five third-order sequences (APT1-5). The final sequence (APT-5) finally fills an intra-shelf basin that was created during the Early Aptian. It contains several higher-frequency mixed carbonate/siliciclastic sequences prograding out from the basin margins towards the basin-centre. Detailed studies have been conducted using seismic, log and core data to evaluate the reservoir potential and quality of these sequences in South East Abu Dhabi.
Prograding higher order clinoform contain top sets, fore sets and toe of slope deposits. Topsets are composed of high-energy grainstone/packstone, rudist-debris and algal floatstones at the shelf margin break. The low-angle fore sets and distal toes of the clinoforms are dominated by low energy carbonate mudstone to wackestone and argillaceous mudstone. Consequently, a diverse and complex distribution exists of reservoir prone facies. Shallow water clinoform top sets are dominated by medium porosity, high permeability, strike-parallel elongated reservoirs. Slope and toe of slope setting create stacks of thin alternating layers of reservoir / non-reservoir with reservoir layers having high porosity but very low permeability.
With the given basin configuration this leads to different targets in different parts of SE Abu Dhabi. Close to the Apt4 margin reservoir prone sequences are dominated by top sets, albeit reservoir is also present in fore set facies. In the southeast corner area of Abu Dhabi farther away from the APT-4 margin and towards the center of the Bab Basin, topsets are not well developed. Here the main attention is therefore directed towards the fore set and toe of slope play.
Given the complexity of vertical and lateral reservoir facies distribution different development and recovery scenarios are needed to test the economic viability of prospects.
AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain