Previous studies performed in Abu Dhabi oilfields, United Arab Emirates, revealed the direct link of seismic wave attenuation to petrophysical properties of rocks. However, all those studies were based on zero offset VSP data, which limits the attenuation estimation at one location only. This is due to the difficulty of estimating attenuation from 3D seismic data, especially in carbonate rocks. To overcome this difficulty, we developed a workflow based on the centroid frequency shift method and Gabor transform which is optimized by using VSP data. The workflow was applied on 3D Ocean Bottom Cable seismic data. Distinct attenuation anomalies were observed in highly heterogeneous and saturated zones, such as the reservoirs and aquifers. Scattering shows significant contribution in attenuation anomalies, which is unusual in sandstones. This is due to the complex texture and heterogeneous nature of carbonate rocks. Furthermore, attenuation mechanisms such as frictional relative movement between fluids and solid grains, are most likely other important causes of attenuation anomalies. The slight lateral variation of attenuation reflects the lateral homogeneous stratigraphy of the oilfield. The results demonstrate the potential of seismic wave attenuation for delineating heterogeneous zones with high fluid content, which can substantially help for enhancing oil recovery.

Fractures and faults were extracted from a reverse time migrated 3D Vertical Seismic Profile (VSP) data acquired over a carbonate reservoir offshore Abu Dhabi in the United Arab Emirates. A specific workflow was used for the extraction of fractures and faults. The workflow was based on data preconditioning (i.e. noise attenuation), semblance based seismic attributes, binary filtering, and clustering. A complex network of fractures was extracted. The dominant strike direction of the extracted fractures showed a good correlation with the dominant strike direction of interpreted fractures from FMI (Fullbore Formation Microimager) and core data at three reservoir zones. A known fault in the area was also detected. The extracted fracture network was then used to compute fracture intensity maps. Fracture intensity maps give indications of zones with high fracturing that may be associated with greater porosity and permeability.