SE Abu Dhabi Aptian 5 Shuaiba System: Understanding a Heterogeneous Reservoir Trend

The study area covers 1,300 km2 in southeastern Abu Dhabi and focuses on the Aptian (Apt.) 5 Upper Shuaiba progradational clinoform system. The Shuaiba Formation has been well-studied at the regional level, but with comparatively less focus on the Apt. 5 system. Studying depositional trends and shoal facies distributions within the Apt. 5 is critical for predicting reservoir presence and quality. Given the complexity of the Apt. 5 system, understanding the key controls over depositional environments, such as paleowind direction, is an important first step. This study combined regional context and geological understanding with previous studies to confirm existing clinoform interpretation, while also delineating four additional clinoform sequences using a reprocessed depth migrated 3-D seismic volume. Isochron maps were also used to group clinoforms into three packages distinguished by common morphologies possibly linked to their respective dominant reservoir facies. Preliminary observations suggest early clinoforms had more rudist build-ups, whereas the later clinoforms were dominated by narrow-shoal beaches. Coalescing clinoform shoal patterns, observed in the spectral decomposition and amplitude extraction maps, likely result from a combination of Bab Basin morphology, longshore current, and dominant paleowind direction during the Early to Middle Cretaceous. Existing interpretations of dominant paleowind direction vary significantly, ranging between E-W and S-N. Interpretations from this study are most consistent with prevailing paleowind out of the east-southeast. The Arabian plate was likely near the equator around 10°S latitude during the Aptian, which supports the southeast wind hypothesis when considering modern Coriolis patterns. Consistent wind influence on shallow water shoal environments would have winnowed mud and increased the proportion of grain-dominated sediment preserved relative to lower energy areas. The grain-dominated facies appear to be reflected in amplitude responses around the coalescing clinoforms, and in the amplitude variations along strike coincident with clinoform edges. Reservoir presence and quality uncertainty can be reduced if these observations can be confirmed. An improved understanding of the Apt. 5 clinoform system in southeast Abu Dhabi, and possible influences on reservoir distribution and quality, will help develop a better understanding of risk for prospect maturation.