Integrated 4D Inversion Approach in Danish Chalk Fields

This paper presents an integrated 4D inversion approach applied in a two vintage regional and multi-vintage field specific 4D processing project during 2013. The most recent regional monitor survey was recorded in 2012. At first we give an overview of the area and available data volumes and introduce a chalk rock physics model to show which 4D changes are to be expected. The 4D inversion workflow is based around a deterministic geostatistical inversion scheme. A time strain inversion is used to obtain a time aligned monitor survey and aligned differences between the 4D processed vintages. In addition, the time strain information is used as prior model information when inverting for 4D impedance changes. Legacy data volumes used in earlier 4D projects were re-inverted with the same deterministic geostatistical inversion algorithm for comparison with the 2013 reprocessed datasets. Altogether thirty main inversion projects were executed within 14 months. We compare inversion results for several processing outputs and also compare adjacent fields. The quick turnaround made possible by the fast inversion software allows the asset teams very early on to interpret and include these data into the daily workflow, well planning or well interventions.