Time-lapse 3D seismic is a fairly new technology allowing dynamic reservoir characterisation in a true volumetric sense. By investigating the differences between multiple seismic surveys, valuable information about changes in the oil/gas reservoir state can be captured. Its interpretation involves different disciplines, of which the main three are: reservoir management, rock physics, and seismics. The main challenge is expressed as "How to optimally benefit from time-lapse seismic". The challenge is divided in two main categories. The first is to link the seismic measurement directly to fluid-flow properties. The second is to fully integrate the time-lapse seismic data within reservoir engineering. The exact relation between time-lapse seismic and reservoir state is rather complex. To get round this relation, a 4D attribute is introduced, whereby the cause (reservoir changes) is directly linked to the time-lapse seismic observation. Different examples are given on how to integrate and benefit from time-lapse seismic information, e.g. by geological parameterisation. Most of the work described comprises integration of the time-lapse seismic information in an automated history matching loop, which is applied to a synthetic model. The use of the Statfjord data set in this research is two-fold. It allows recognising challenges the industry is currently facing, as well as testing proposed algorithms.