f Improved Seismic Resolution of the Ty Reservoir by AVO-Processing, Sleipner Øst Field

The field has its main production from a Paleocene deepwater sandstone reservoir . The main geophysical challenges in the field have been to identify the top reservoir, the reservoir pinch-out zone and internal reservoir geometry. To understand the seismic response at reservoir level a geophysical modeling study (including AVO-modeling) was performed. Well data and pre-stack data from 10 lines were used in the modeling. The modeling showed that the mis-tie between synthetic seismograms and surface seismic data in the hydrocarbon bearing part of the reservoir was caused by an AVO effect. Both the modeled and the real CMP-gathers showed a rapid decrease of the amplitude with offset including a polarity reversal. To avoid the effect of this polarity reversal on the stacked data the concept of Intercept-stack was introduced. The Intercept-stack is an extrapolation of the near offset reflectivity to zero offset.