Multi-Azimuth Modelling, Acquisition and Co-Processing for Joint Structural Interpretation and Model-Uncertainty Assessm

Following the discovery of the K18-Golf Rotliegend gas field with the K18-7x well, its consecutive appraisal with K18-8, as well as extensive illumination and full waveform imaging studies, it became apparent that an innovative approach was needed to significantly improve the seismic image. Due to the very complex overburden, only patchy illumination was achieved with conventional single narrow-azimuth towed streamer seismic. Therefore, a multi-azimuth acquisition and co-processing with legacy 3D was pursued to significantly improve subsurface illumination at acceptable cost. Following the multi-azimuth co-processing through time and depth imaging, the interpretation posed challenges in terms of number of seismic volumes as well as relative image quality variations. After treating each acquisition as stochastically independent realisation of the earth, their relative and independent quality variations could be interpreted in terms of imaging and feature position uncertainty.