Integrating Multiple Datasets to Improve Reservoir Understanding across Halfdan NE, Danish North Sea

This abstract aims to illustrate, how the GeoSphereTM was used for the first time in a horizontal Maastrichtian Tor well on the Halfdan Northeast Field in the Danish North Sea. The tool helped to ensure optimal well placement and improved reservoir understanding.

The formation in this area was interpreted as “disturbed chalk,” and associated with large uncertainty on reservoir geometry. Well- and seismic data show that the reservoir could have an apparently complex and mixed stratigraphy, making it difficult to navigate during drilling.

The real time MWD results allowed for a change in interpretation and successful placement and navigation of the well through more than 60 small-scale closely spaced conjugate normal faults to planned TD. Production is above expectations.

Post drilling, the MWD results integrated with multiple datasets including 3D- and 4D-seismic data, standard log interpretations, biostratigraphy and cutting analysis, provided valuable additional information on the reservoir structure. This allowed for a different an improved interpretation of the nature of the chalk in the area, which is only obtainable by integrating multiple datasets: Top Ekofisk is much more uneven, the Tor is significantly faulted, and no evidence of re-sedimentation processes was found in this part of the disturbed chalk area.