Inverse modelling of surface subsidence to better understand the Earth's subsurface

Surface subsidence can have major repercussions. A classic example is the seabed above the Ekofisk field, offshore Norway, where excessive subsidence made it necessary to raise the drilling platform by 6 m in the 1980s. On land, subsidence may significantly increase the risk of damage to buildings and infrastructure. But, there is more to say about subsidence. Observations of subsidence can also give us a better handle on the subsurface processes like compaction behaviour of a reservoir, and can tell us more about the reservoir itself: about undrained compartments or the strength of the aquifer. However, to get the information from subsidence data, you have to carefully follow an inver-sion procedure. This inversion exercise is a big challenge, in which all the available knowledge has to be used to the fullest possible extent. In this article we report on the work we have recently performed in this area.