Abstract

The primary objective of this research is to characterize the Smeaheia Field in the Northern North Sea using a hybrid seismic inversion framework that integrates Simulated Annealing (SA) and the Quasi-Newton Method (QNM). This approach focuses on delineating acoustic impedance variations to better understand the reservoir properties relevant for potential CO₂ storage. Petrophysical analysis of well 32/4-1 identifies the Sognefjord Formation characterized by marine sandstone, low gamma ray, high porosity, and low acoustic impedance as the primary target reservoir for injection. A composite trace analysis at the well location was conducted to validate inversion accuracy, achieving a correlation coefficient of 0.92 with the well-log impedance using the hybrid method, outperforming the SA only result (0.77). Within the Sognefjord interval (1300-1400 ms), impedance values ranged from 6000 to 7000 (m/s·g/cc) consistent with favorable reservoir properties. The hybrid algorithm also demonstrated faster convergence and lower error (mean=0.05) compared to SA alone. Overall the results confirm that the hybrid optimization framework enhances inversion reliability and geological interpretation, offering critical insights for safer and more effective CO₂ storage site selection.