In order to validate existing models of sedimentation in active sedimentary environments, detailed stratigraphic information is indispensable. Near-surface geophysical methods provide a means to acquire high-resolution images of the stratigraphic succession in the shallow subsurface. Land-based and marine methods have been tested in the Verdronken Land van Saeftinge. This intertidal flat area is cut by numerous tidal gullies, and high tidal amplitudes enable the application of different techniques at various water levels. Data acquisition focused on the upper 10 – 20 m of the active sediment bodies. Applied techniques include high-resolution seismic acquisition, geo-electrical methods (DC resistivity), electromagnetic techniques, CPT, and manual drilling. In general the acoustic methods allowed more reliable and detailed interpretation of the sedimentary structures than the electric/electromagnetic methods. The latter suffered from the effect of tidal action and salt-water intrusion, and their application on land proved very strenuous. CPT and shallow cores provided valuable ground-truth information. The results clearly indicate that no single technique can provide all the answers. Only an integrated use of (complementary) methods will allow getting a better grip on the sedimentary architecture and preservation potential in active estuarine sedimentary environments.

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The Dutch Koekoekspolder geothermal doublet was drilled in 2011. It targets the Permian Rotliegend reservoir. The reservoir properties encountered were less favorable than expected pre-drill. Post-drill integrated evaluation of vintage data and the new data from the geothermal wells resulted in a refined depositional model of the area. The Rotliegend sediments comprise predominantly horizontally, bimodally laminated fine to coarse grained red sandstones. These sediments were deposited on an aeolian sandflat. Gypscretes were formed on this sandflat in the relative low-lying areas, which coincide with palaeo-lows of the pre-Permian palaeotopgraphy. These gypscretes were periodically exhumed and (partly) eroded providing gypsum grains. These were subsequently incorporated in the predominant quartz rich sand sediments on the sandflat forming typical bimodally laminated Aeolian deposits. The gypscretes are now present as pervasively anhydrite cemented horizons haphazardly vertically distributed. The improved understanding of the formation and occurrence of the gypscretes, in combination with advanced seismic attribute analysis can help in the identification of low-permeability zones that may impede the performance of future doublets.

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