The De Wijk Vlieland Sandstone, an Analogue of a Shallow Marine Environment: ABSTRACT

Abstract

The De Wijk gas field located in the Netherlands was discovered in 1949 and has been in production since 1955. The structural geology of the area is dominated by salt tectonics producing domal traps of which De Wijk is an example. The field consists of a sequence of stacked reservoirs, of which the Vlieland Sandstone (Cretaceous) is the most prolific producer. The existing wells all pre-date the 3-D seismic which was acquired in 1990. Of the wells penetrating the Vlieland Sandstone, the initial production rates varied from 50,000 m3/day to 1,000,000 m3/day. Prior to the 3-D seismic no geological model could satisfactory explain this range in productivity. The interpretation of the 3-D seismic over the field, especially seismic attribute mapping, highlighted sedimentological features previously unseen in the 2-D lines. Using isochron, azimuth and amplitude extraction`s, channel like features were identified. These channel like features which enter the De Wijk depositional basin were identified as the conduits for sediment supply. Using 3-D mapping tools, the depositional basin and surrounding hinterland (Triassic Palaeotopography) were modelled. The 3-D visualisation gave direct indication of the sediment source area and direction of transport. This information indicated that during deposition of the Vlieland Sandstone, two sourcesmore » of sediment supply were in existence. Correlation highlighted that the productivity distribution was dependent on the sediment source. The 3-D seismic, well, core and productivity data were integrated to construct a geological model that predicts the distribution of high productive sands. Using the geological model it was possible to plan additional infill wells to accelerate the production from the Vlieland reservoir.« less