Downflank hydrocarbon potential identified using seismic inversion and geostatistics: Upper Maastrichtian reservoir unit, Dan Field, Danish Central Graben

Porosities considerably higher than anticipated from porosity/depth trend m odels are encountered in a Maastrichtian reservoir unit on the western flan k of the Dan Field. Because there is a good correlation between seismic imp edance and well log porosity, inverted seismic data are used to infer that highly porous zones are widely distributed. The distribution of these high porosity zones is predicted using geostatistical methods based on the inver ted seismic data. These predictions contradict the general assumption that porosity deteriorates with depth in the study area. Annealing cosimulation is applied using inversion-derived seismic impedances as soft data and well log porosities as hard data. The sensitivity of the porosity characterizat ion to hydrocarbon in-place estimates is investigated through the calculati on of water saturations using height above free water level and simulated p orosity as input parameters. Multiple realizations show that calculated hyd rocarbon in-place estimates are more sensitive to the location of the free water level than to uncertainties related to the geostatistical reservoir c haracterization.