A 3D GEOLOGICAL MODEL FROM SOUTHERN JUTLAND, DENMARK: COMBINING MODELING TECHNIQUES TO ADDRESS VARIATIONS IN DATA DENSITY, DATA TYPE, AND GEOLOGY
To transform airborne electromagnetic data into geology is complicated with many pitfalls and requires geophysical as well as geological insight. Thorough geological background knowledge must be implemented in the interpretation while concurrently identifying and acknowledging the basic limitations of the method. Cognitive modeling is therefore normally preferred.
A large-scale airborne transient electromagnetic survey (conducted with the SkyTEM system) and 38 km high-resolution seismic data have together with new and existing borehole data and hydrocarbon exploration data been available for the model construction. The data are unevenly distributed across the area and the entire model area is not covered by the SkyTEM survey. Cross-cutting tunnel valleys, faults, erosional unconformities, delta units and glaciotectonic complexes are among the geological features identified in the area. The complexity varies as a result of shifting geological environments across the model area.
A broad geological overview and understanding of the area is gained by cognitive co-interpretation of the geophysical and geological data. To address the high level of detail in the SkyTEM data, the model is constructed as a voxel model with lithofacies attributes supplemented with surfaces. The model is mainly constructed manually by cognitive interpretation, but geostatistic inversion has been used to distribute lithology to voxels within the glaciotectonic complexes (where SkyTEM exists). Stochastic modeling (SGeMS) has been used for the shallow part of the subsurface in the area without SkyTEM data.