AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
3-D Seismic Characterization of Zubair Pay Sands of Sabiriyah Field, North Kuwait, Kuwait
(1) Field Development Group, North Kuwait, Kuwait Oil Company, Ahmadi, Kuwait.
The 3-D seismic data of Sabiriyah Field of North Kuwait, Kuwait, have been successfully used for delineation and mapping of productive reservoir intervals within Zubair Formation. Zubair Formation of Early Cretaceous age is one of the major producing reservoirs of North Kuwait. In Sabiriyah Field, Zubair Formation is classified as upcoming reservoir where as in the adjoining Raudhatain field it is a major producing reservoir with similar geological depositional settings and reservoir architectures as that of Sabiriyah field. Zubair Formation is about 1400feet thick and predominantly clastic in nature. The entire interval is broadly divided into Upper, Middle and Lower units. Wide varying depositional environments from tidal to estuarine to wave or shoreface to fluvial dominated prevailed during the deposition of Zubair and has been reflected in the complex reservoir geology. In Sabiriyah Field majority of Middle and partly Upper Units are mostly water wet and is attributed to leakage of oil where inter-bedded seals are breached across faults whereas the Lower Units have commercial hydrocarbon accumulation. The challenge is to delineate and map these productive relatively thin reservoir intervals of Lower Zubair Unit. Delineation of these sands by conventional interpretation methods is difficult because of thin and discontinuous occurrences, high degree of vertical and lateral un-reliability in net sand thickness and limited bandwidth of seismic data.
To overcome these limitations a comprehensive interpretation workflow was designed and implemented which is based on combination of amplitude slices, various types of attribute maps generated in the vicinity of productive intervals and 3D visualization, which revealed anomalies in the shape of fluvial sand bodies that grossly correlate with fluvial depositional facies interpreted from well logs and sand thickness maps. The study demonstrates the imaging power of 3-D seismic attributes in characterizing complex reservoirs which enhanced and enables in fine tuning and firming up the positioning of development wells.