Optimization of PP and PS 4D turnaround using iterative processing: Clair Ridge ultrahigh-density OBN survey, North Sea

Accelerated completion of 4D processing projects supports closer to real-time interpretation of reservoir dynamics and influences production planning. It also enables an increased acquisition frequency, achieved either by repeating the baseline survey or by conducting localized investigations in specific areas of interest. The paper presents the key data challenges encountered in processing the Clair Ridge nodal survey. The processing campaign commenced with an iterative processing workflow for the 3D 2017 baseline survey, focusing on a rapid turnaround sequence centered on up/down deconvolution. A baseline workflow was established for the 4D monitor survey acquired in 2023, followed by a 4D-specific iterative workflow to deliver high-quality volumes for both pressure (PP) and converted shear (PS) data in just over one month. The rapid turnaround workflow demonstrates that both PP and PS data can be coprocessed with nearly identical workflows. Additionally subsurface PS measurements hold the potential to provide valuable subsurface information for aiding 4D data interpretation. Unlike pressure waves, converted waves do not transmit through fluids and travel slower through the subsurface. As a result, these waves are less affected by changes in saturation but are more sensitive to pressure effects.