Data assimilation for subsidence analysis of the Groningen region: A multi-scale study with importance sampling

The Groningen gas field has been compacting since the start of gas extraction in the 1960s because of pressure depletion in the reservoir, causing subsidence in the Groningen region. Geodetic techniques, such as optical leveling and satellite-borne Interferometric Synthetic Aperture Radar (InSAR), provide displacement estimates for subsidence monitoring. InSAR displacement estimates provide observation points with a higher spatial density and temporal sampling than leveling. Whereas identifying leveling benchmarks with subsidence caused by the compaction reservoir is possible, the InSAR’s sensitivity to multiple subsidence sources (e.g., compacting reservoir, soil motion, and infrastructure instability) complicates the identification of subsidence-driving mechanisms in InSAR estimates. Combining physics-based subsurface models with InSAR estimates into data assimilation is an approach to estimating to what extent reservoir compaction and other subsurface processes contribute to the total subsidence.....