Time-Lapse Bathymetry Processing for Seabed Subsidence Monitoring

Summary Seabed subsidence caused by reservoir compaction is a common phenomenon occurring during oil and gas production. In the offshore environment it is monitored using GPS (Global Positioning System) receivers on surface installations such as production platforms. However, the area affected by seabed subsidence can extend away from this single point of measurement, especially when the reservoirs are produced using long horizontal wells. To fully map the subsiding area dedicated seabed surveys are required. In absence of dedicated time-lapse seabed surveys we decided to use bathymetry data recorded during 3D and 4D seismic surveys over several fields in the Danish sector of the North Sea. Due to limited accuracy and sparse spatial resolution such data are rarely used for seabed bathymetry and subsidence measurements. However, by developing a dedicated processing workflow it has been possible to significantly improve the estimated accuracy of the subsidence calculation to 0.3m. This extended abstract describes the data processing workflow, the results and their current utilization in geomechanics and reservoir management. It also discusses potential future utilization in other technical areas.