| Popis: |
Forward modeling using Britannia data shows a characteristic set of subtle reservoir AVO signatures due to the significant Vp:Vs contrast that exists between sands and shales (Figure 1). The same responses can be seen, to a certain degree, in an AVO class volume generated over the full field from nearand far-angle stack seismic volumes. A top sand class-1 AVO response was mapped over Britannia platform west and tied to existing well control. Ten of fifteen wells in the area confirmed the class-1 response was indicative of sand presence in the upper reservoir, while five of fifteen wells contain more upper reservoir sand than is suggested by the class volume. No “false positive” class volume predictions are seen. Work to date provides encouragement that AVO information can discriminate sand from shale at the Britannia reservoir level. Significant potential exists to improve reservoir characterization, optimize location of future development wells and positively impact overall field development. The workflows used in this study may also be applicable to similar high impedance reservoir characterization studies in other basins. Britannia is a Lower Cretaceous, deep water turbidite reservoir located approximately 225km north-east of Aberdeen, Scotland (Hill and Palfrey, 2003). A continuous platform drilling program is in progress, set to continue through 2007, with well targets becoming increasingly higher risk as drilling step-out increases. Optimally locating development wells is critical to the ongoing success of the field. Full stack seismic data, however, is limited in the degree of reservoir information provided. Depth of burial reduces the dominant seismic frequency at the reservoir level to about 25Hz. In addition, a major chalk interval in the overburden acts as a source of multiple energy and limits the degree of usable amplitude at far offsets. |
