Abstract

The work presented in this paper consists of a 3-D long offset pre-stack simultaneous inversion study on the Gryphon Field, North Sea. The injected sands reservoir in the Balder formation represents the main reservoir of this field. The use of higher angles should provide better understanding of the reservoir in terms of fluid distribution in the Balder and in the injected sands of the Frigg formations. The aim was to recover the density information from the long-offset seismic as well as the common elastic attributes such as the P-Impedance, Rho-Lambda and the Vp/Vs. The data pre-conditioning sequence and the use of a long offset dataset was found mandatory to achieve an optimum imaging of the reservoir and to estimate the density. This important pre-conditioning significantly improves the imaging, detection of the injected sands, and also increase the signal-to-noise ratio of the various angle stacks used for the simultaneous inversion. Inversion of 8 angle stacks with angle up to 580 degrees was carried out. The use of higher angles provides better understanding of the reservoir in terms of fluid distribution in the balder formation and in the injected sands of the Frigg formation